Prolog duplicate list

Prolog duplicate list. Another way of removing duplicates is to use sort/2. at last, get rid of the values of I in the sorted list—we don't need them anymore. Arithmetic and lists in Prolog . Possible duplicate of Prolog: list of numbers – Guy Coder. True if List is a list of dicts that all have the same keys and Keys is an ordered set of these keys. Here's a simple The following code describes the process to remove duplicates from a list in Prolog. distinct(:Goal) distinct(?Witness, :Goal) True if Goal is true and no previous solution of Goal bound Witness to the same value. counting the elements of a list of lists PROLOG. 4. Count number of occurrences in a list in Prolog. 8. duplicate(L, V) :- % nth0 gives the index (from 0) of an element in a list % element V is at the place Id1 in L nth0(Id1, L, V), % element V is at the place Id2 in L nth0(Id2, L, V), % Id1 is different from Id2 % It is more usefull to say that Id1 < Id2 % Thanks **false** for domain_error(unique_key_pairs, List) if List contains duplicate keys. combine([X|Xs], Y) :- First we want to recursively flatten the head. About; It removes duplicates, so if the sorted list is exactly one shorter, you had exactly one pair. Below is my knowledge base: connection(bus,kerkrade, heerlen, 1100, [det] list_to_assoc(+Pairs, -Assoc) Create an association from a list Pairs of Key-Value pairs. It should work as follows: ?- remove_duplicates((a, b, a, c, d, d). 1, is_list/1 just checked for [] or [_|_] and proper_list/1 had the Prolog: check against duplicates in a list. x_dup(X,[X|Ys]) --> % if X and the head of the list are equal. Prolog how to prevent repetitive answers. It should work as follows: ?- remove_duplicates([a, b, a, c, d, d), List). x_dup(X,[Y|Ys]) --> % if X and the head of the input list. For example, given T=[1], which L satisfies X=2? the answer is [1,2] or [2,1]. How to remove duplicates from a list in SWI-Prolog? 1. It has tasked me with removing duplicates. It shows a bit of syntactic detail, like the 'if/then/else', that in Prolog has a peculiar form. Or (less efficiently): list I have remove code that will take an element and a list and return a list with occurrences of that element in the list removed. Explain your function. both efficient (leaving behind choice points Does anybody know how I can go about determining/ensuring that there is exactly one duplicate element in a prolog list? I am studying for a test. I'm trying to learn prolog and I'm working on a problem where I have two functions: findSiblings(X,L):-sibling(X,L). flatten/2: Is true if FlatList is a non-nested version of NestedList. How to construct a list from two lists in prolog. Hot Network Questions How to choose between 3/4 and 6/8 time? Did any other European leader praise China for its peace initiatives since the outbreak of the Ukraine war? I have written the following code, which finds the first duplicate in a given list and 'returns' it as L, how do I make this 'return' all duplicates in the list as L? Ex. 0. You have to write it yourself. one_duplicate(L) :- sort(L, Sorted), length(L, Len simplest way without any intermediate list using list. i need to create myPermutation(L1,L2). check if element is repeated in list in prolog. and if you have a single element you have a singleton list. Writing a test predicate to see if all duplicates have been removed from a list. Hot Network Questions Vilna Gaon - Torah can bring you up or bring you down Story about Jesus being kidnapped by the church Create edges for a set of vertices with Geometry Nodes Prolog: find and put into the list duplicates. gistfile1. That is a set (∅, the empty set) by definition. How to remove the repeated members in a simple list [ prolog ] 0. . getting prolog not to repeat answers. combine(XS,XXs), The way to check whether a variable is still free is with the ISO predicates var/1 and nonvar/1, which are true if their argument is a free variable or instantiated. Hot Network Questions Maximum number of ones in a full rank matrix with a restriction “I know what’s best but I do the opposite” translation? And then my remove_duplicates predicate. {dif(X,Y)}, % are different. 1. Prolog: find and put into the list duplicates. hello everyone pls forgive any misuse of the language. union as presented above OTOH is not about sets, but about lists. The above directly translates to the predicate lists_sortedBySecondItem/2: In other words, find out if all the lists in list1 intersect with any of the lists in list 2. E. Prolog: How to eliminate duplicates of list of elements without changing the order of the elements? 0. Checking repetition in list - Prolog. The correct way to check if a list is a set in Prolog is to sort it, removing duplicates, and check if its length is still the same. Double elements in list using prolog? 0. list_swizzle([], L, L). The pairs must occur in strictly 7 - Processing lists in Prolog: 1 9 Consolidation moment Lists are used to store data/information that varies in quantity: 1. For list processing, this means (in general) you have to decide how to handle the empty list and how to handle an element in front of some other list. it should've worked as is. ListOfLists must be a list of possibly partial lists – What I was saying in my comment was : I want two items from the list L wich are not in the same place so. In my head this makes sense, it checks if the Head is a member of the tail and if it is, it doesn't add it to the Without list, else it does. Testing if all lists in a list have the same length. What is set of list?Set should have these attributes: The next challenge is to change the value of a list. It holds for the list [L|Ls] if our initial predicate (p/1) holds for L, and ps/1 holds for the How do I delete all but duplicates from a list in prolog. /2) in SWI-Prolog (2 answers) Closed 5 years ago. So, pan(A,B,[A],Len) is backtracked and all solutions Len are put into the list Z. If you want to get just unique values in list - use function list_to_set/2:. True if Set is a proper list without duplicates. Viewed 2k times 0 This question already has an answer here: Returning a list in prolog (1 answer) Closed 9 years ago. do show us the code you tried. Our definition avoids unpacking each list element twice and provides determinism on the last element. Example:?- dupli([a,b,c,c,d],X). Eliminating Duplicate Answers in Prolog The Question . i need help on how to write a predicate that will duplicate the items in a list, where the left argument is a list and whose right argument is a list consisting of every element Delete matching elements from a list. G = [_23512,hello,_23524 One should note that to append an item to a prolog list requires traversing the entire list, prepending is a trivial operation, due to the structure of a prolog list. (can be autoloaded) [det]list_to_set (+List, ?Set) True when Set has the same elements as List in the One is improve your logic to avoid double solutions. Multi lists of atoms are in some situations a good representation of a flat list True if Sorted can be unified with a list holding the elements of List, sorted to the standard order of terms (see section 4. You can just use select/3 [swi-doc] here with Hi, Just by error, I found that you can assert the exact same fact (same functor and same argument) as many times as you want. 0. What do you mean exactly because I can't get it. duplicate(L, V) :- % nth0 gives the index (from 0) of an element in a list % element V is at the place Id1 in L nth0(Id1, L, V), % element V is at the place Id2 in L nth0(Id2, L, V), % Id1 is different from Id2 % It is more usefull to say that Id1 < Id2 % Thanks **false** for [det] list_to_set(+List, ?Set) True when Set has the same elements as List in the same order. Hot Network Questions I need to get duplicates out of a nested list. Removing Duplicates while maintaining order in Prolog. I am using Prolog and I am trying to find the intersection or the common elements between two lists and the result should not contain duplicates. Hot Network Questions How can a Kenyan Deputy President challenge his impeachment after it passed the Senate? One should note that to append an item to a prolog list requires traversing the entire list, prepending is a trivial operation, due to the structure of a prolog list. Combine two lists without duplicates prolog. findall(Len, pan(A,B,[A],Len), Z) will produce the list Z with all Len's , such that pan(A,B,[A],Len) succeeds. % the same holds for X and the tail. Hot Network Questions Molecular dynamics and I need to define a predicate which detects if a list contains repeated elements. How can I copy all the elements of one list N times in a new list with simple commands of Prolog without using Maplist,findall or libraries. I need to implement this function: cod_first(X, L, Lrem, Lfront). Removing consecutive duplicates from a list in Prolog. 12. To get the most out of Prolog, focus on describing the conditions that must hold for the solutions you want to find! You want to find a list without duplicates? Describe what such a a list must look like. And in such cases, there is nothing to "repeat" yet: We start from nothing, and ask Prolog what solutions there are in general. The predicates middle([1,2,3],M) and middle([1,2,3,4],M) should both return 2 as a result. % (you don’t need explicit recursion, actually). Removing heads from lists in Prolog. See also ord_intersection/3. Given the above solution statement, a possible translation to Prolog code might look like this: dupli([], []). Return a list that only includes duplicate elements. " A list in Prolog is an ordered collection of items denoted as [i1, i2, , in]. duplicate(L,[1,2,3,3,4,4]). Prolog: Build a list with repeated elements of other list. Hot Network Questions How to choose between 3/4 and 6/8 time? Did any other European leader praise China for its peace initiatives since the outbreak of the Ukraine war? To remove duplicates from a list in Prolog, you can define a predicate that checks each element against the rest of the list and removes duplicates as it finds them. Elements are considered duplicates if they can be unified. x_dup(X,Ys). The tail of the outer list is TR, i. Ask Question Asked 3 years, 5 months ago. Here's what I have so far, it deletes the duplicates fine. for example I ask Prolog's query: ?- copy_list([a,b,c, The solution by @WillemVanOnsem, derived from the OP code, uses term unification when comparing the element to be removed with the elements of the list (an alternative would be to use term equality). My idea was to cut first and last element of list using recursion. The complexity of this predicate is |Set1|*|Set2|. So, my question is How can I detect and remove the duplicate clauses? If the clauses are identical, does not look like retract can help. Elements E1 and E2 are considered duplicates iff E1 == E2 holds. 1. Hot Network Questions You didn't surface Parent in the head of the rule, but the proof that Prolog found is different, so it's a different solution. prolog This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. For this you must define set concept. The SWI-Prolog definition differs from the classical one. Missed opportunity: Powered by SWI-Prolog 9. In your predicate, the second argument should always represent the result of duplicates being removed from the first argument. I had previously found that answer, but I thought that it only returned whether a given atom matched every predicate in the list. Define your base cases first - if you have no lists to combine you have an empty list. Where X and Y are names, and L is the [det] delete(+List1, @Elem, -List2) Delete matching elements from a list. Removing duplicates from Prolog query results (Visual Prolog using Pie) 1. List building problems. And that's what that 2nd line in your code is telling us, it says, "appending an If you look at your implementation of unique/1, you’ll see that both the second and third clause will succeed given a list with one item ( if T in clause 3 is []). Find repetitions in a list. [det] union(+Set1, +Set2, -Set3) True if Set3 unifies with the union of the lists Set1 and Set2. Logically I want to take a list cons the head with the recursive call on the new list Creating lists do not include duplicates in Prolog. It's usable in all directions!" I don't understand why I should dif/2 instead of \=? Especially, you highlight directions. 1 Prolog, remove repetitive results in generation. For example: ?- I'm trying to find duplicate (non unique) items in a list. remove_duplicates([H | T], List) :- member(H, T), remove_duplicates( T, List). Is there a good way to sort a list of list with fixed length by some index. However, my code is I want to delete a given element X from the list in Prolog. the tail of the output list returned from the recursive invocation. I do get a satisfying answer but this should be the only answer. Removing duplicates from a How can I copy all the elements of one list N times in a new list with simple commands of Prolog without using Maplist,findall or libraries. Im trying to create a Implement a Prolog predicate remove_duplicates/2 that removes all duplicate elements from a list given in the first argument and returns the result in the second argument position. Step 1. The only answer should be S = [a, b, c], instead of getting an Prolog Duplicate a word in list. For example: delete(5,[2,3,4,5,6,7,8,9]). Here's a simple implementation: % Base case: If the input list is empty, the result is also empty remove_duplicates([], []). We can combine that to realise substituting all appearances of a sublist into another as illustrated below. 1 EDIT: So it turns out this is a duplicate of List of predicates in Prolog. And it works. that varies whilst the program is running. Get all sets of list in prolog. Prolog List Squaring, Modifying element in List. If duplicates are removed, Prolog, filter duplicates, while keeping list order. About; Products Finding intersection between two lists without duplicates in prolog. insect(bee). Viewed 102 times 0 This question already has answers here: How to use list constructors (. One is improve your logic to avoid double solutions. Before going any further, we need to introduce two additional features of Prolog that will come in handy in writing future programs, arithmetic and lists. Hot Network Questions What was the first "Star Trek" style teleporter in SF? What's the statistical historical precedence for generalisation beyond overfitting? How do I delete all but duplicates from a list in prolog. There are many different lists representing the same set, but as lists they are considered different. How to find number of same elements in list Prolog? 2. Nested list duplicate. It is possible for the elements to be in different orders. Hot Network Questions Sylvester primes While working in Prolog I frequently encounter that my implementation produces duplicate results when querying specific things. , memberchk/2, length/2. (This seems obvious in retrospect, but it only occurred to Prolog: How to eliminate duplicates of list of elements without changing the order of the elements? 0. L = a. I want create my own – theantomc. 6). And I am allowed to use the predicate deleteLast. See also select/3, subtract/3. How to check the repeatable variables in a list in prolog. Hot Network Questions Prolog: check against duplicates in a list. Reversing list in Prolog. I thought I could simply find out how to get duplicates out of a regular list and then make a rule for getting subsets then somehow combine them and it'll work but I think I'm confusing myself more by doing that. Availability::- use_module (library (lists)). " This is a helpful property. The other is to use SWI-Prolog’s distinct/1,2. both efficient (leaving behind choice points Creating lists do not include duplicates in Prolog. You can see this if you try the query ?- city(A), unique([A]). B) and (B,A) as the same, use A @> B instead of not(A=B) (which you better write as \+ A = B or even better as A \= B). dupli(L, O) :- dupli_t(L, [], O). Define a relation in Prolog that eliminates duplicate consecutive elements from a list. My aim is to select the sublist with a certain Swi-Prolog Select List from List of Lists [duplicate] Ask Question Asked 6 years, 5 months ago. 1 There are roughly two options. Why does the same Prolog query produce duplicate results only in specific cases? 1. List). Using the atom '[]' as list terminator prevents dynamic distinction between atoms and the empty list. On the other hand, \+/1 is specified as a built-in predicate. For example, we cannot use multi lists (arbitrary deeply nested lists) of atoms. duplicate_list([],[]). The above calls recursively for the tail. g. Tags: LogicalCaptain said (2020-04-29T11:22:34): 0. I'm new to prolog and I wrote this code that suppose to return all the sub-lists of a list without some member of them. But can result in unexpected results when the terms are not ground. it can be an atom, a list, a compound term. 5. Of course, exists/2 should The way to check whether a variable is still free is with the ISO predicates var/1 and nonvar/1, which are true if their argument is a free variable or instantiated. Matching Elem with elements of List1 is uses \+ Elem \= H, which implies that Elem is not changed. index(): z = ['a', 'b', 'a', 'c', 'b', 'a', ] [z[i] for i in range(len(z)) if i == z. – SWI-Prolog extends this predicate to deal with dicts. Eliminate consecutive duplicates of list elements. 7. One important difference is findall returns an empty list whereas bagof returns false/0 if there are no results for the input, making bagof usually the better choice for logical programming. My six ways of list processing in Prolog list has now reached nine with the addition of using SWI Prolog’s indexing predicates. We can prepend an item to an existing list as simply as: prepend( X , Xs , [X|Xs] ) . But with those three control constructs you can define your own negation-as-failure predicate and then use it to solve this problem efficiently. memberd_t/3 is equivalent to memberd/2 + non_member/2, so we could define How do I delete all but duplicates from a list in prolog. EDIT: So gnu prolog doesn't have built-in predicate list_to_set. For instance (user input is in red): ? - has_duplicates ([a, e, b, d, s,el). List - Prolog: How to eliminate duplicates of list of elements without changing the order of the elements? 0. Pr subtract does a list-from-list subtraction to remove the unique elements from all the elements, leaving the Unwanted duplicate elements. [X,X], % X is twice in the output list. note that keysort/2 preserves duplicate items. Remove duplicates in list (Prolog) 5. Remove duplicate values from a list in Prolog. I cannot make use of findall/3 or related predicates. Backtracking yields alternative solutions. so, this is exact duplicate of the one you linked. See also section 5. Skip to main content. is_set/1: repeated([M],0). e. See more linked questions. Being a beginner to prolog, I am trying to remove all duplicates from a list. The sort/2 predicate can sort a cyclic list, returning a non-cyclic version with the same elements. For example combine([a I would like to get the middle element of a list in Prolog. 1 Prolog remove all duplicates function. Its functionality is that it matches a list of integers that have a domain of 1 to N with no duplicates and length N. duplicate_list([H0|T0],[H0|T]) :- duplicate_list(T0,T). This is correct for all kinds of reasons, from very pragmatic (easy to program) to purely theoretic (it is the only robust approach to checking if a singly linked list is a set). which given a list L1 (which has elements with many concecutive appearances) returns a list L2 which is L1 sorted in a way that there are no two concecutive elements which are the same) The ISO Prolog Core standard specifies call/1, !/0, and fail/0 as control constructs, not as built-in predicates. I didn't realise that you can pass a variable instead of an atom and have it return every case that matches as well. [ISO] sort(+List, -Sorted) True if Sorted can be unified with a list holding the elements of List, sorted to the standard order of terms (see section 4. Viewed 670 times 0 I'm writing a prolog homework that asks me to combine two lists together but without duplicates. Hot Network Questions [det] list_to_assoc(+Pairs, -Assoc) Create an association from a list Pairs of Key-Value pairs. Implement a Prolog predicate remove_duplicates/2 that removes all duplicate elements from a list given in the first argument and returns the result in the second argument position. New empty cells (fresh variables) are created for any unbound variable in the original term:?- length(G,3),duplicate_term(G,H),G=[_,hello,_]. Remove duplicates in list (Prolog) 1. the Consider the possibilities. , dif/2, to denote that two terms are different. Prolog - remove from a list all repetitive elements (only keep unique elements) 1. 2 How can I prevent duplicates in prolog. Obviously. combine(X,[X]). Later on, Prolog is also going to notice taht P1 = homer, P2 = herb, Parent = abraham, and give you a third identical solution. The left-most copy of duplicate elements is retained. Prolog check for duplicates in answer to query (easy way?) 2. What if we've reached the end of that list? Then we've arrived at the empty list, and appending an empty list with another list gives us that list as the result. Syntax [H|T] unifies with your list in such a way that H becomes the head of the list, and T becomes its tail. Example: ?- dupli([a,b,c],3,X). Share. As previous answers need to be copied Eliminate consecutive duplicates of list elements with prolog. List = [b, a, c, d] Yes . 12 Prolog uses predicates, not functions. Open a text editor, such as Notepad, and save your file with the name "remove_dups. Seems like something like this would be the easy way: intersection( Xs , Ys , Zs ) :- sort(Xs,X1) , % order and de-dupe the 1st list so as to produce a set sort(Ys,Y1) , % order and de-dupe the 2nd list so as to produce a set merge(Xs,Ys,Zs) % merge the two [ordered] sets to produce the result . Prolog not unique elements in predicate call. you will try this piece of code to generate a list containing n times replicated list Prolog Duplicate a word in list. To review, open the file in an editor that reveals hidden Unicode characters. [det] intersection(+Set1, +Set2, -Set3) True if Set3 unifies with the intersection of Set1 and Set2. The question is completely unclear: Is it about merging sorted lists? Sorted lists of numbers, maybe? Is it about a kind of append that only keeps one copy of a shared suffix of the first list/prefix of the second list? Is it about dropping duplicates in some more general sense? Here is a solution that drops the shared suffix/prefix. keysort(List1, List2) succeeds if List2 is the sorted list of List1 according to the keys. Possible Duplicate: Prolog delete: doesn't delete all elements that unify with Element In Prolog if you write this: delete([(1,1),(1,2),(1,1),(3,4)],(1,_),L). True when List2 is a list with all elements from List1 except for those that unify with Elem. This is SWI-Prolog specific. For example,?- eliminateDuplicates([a,b,b,c,a,c list_swizzle(L, [], L). index(z[i])] >>>['a', 'b', 'c'] Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Visit the blog This is for GNU-Prolog. Force Prolog to choose unique values of variables. Something like dog-[bull, chiwawa, lucky]. Using if_/3 and (=)/3 a logically pure implementation can be . msort/2 is similar to sort/2 except that duplicate elements are not merged. Modified 9 years, 10 months ago. I know that there are similar posts that solve that question but I have not found one that just uses deleteLast. and arity 2 and the second argument is a list. 2) Define the predicate repeat(X,Y,N), which is true if the list Y contains each of the elements X repeated N times. However, all elements in a list must Creating lists do not include duplicates in Prolog. I will upvote answer. Hot Network Questions Why, fundamentally, does adding sin graphs together always produce another sin Use append/3 for substitution in a list. I was recently asked Say I have the sister relation defined like this: sister(X,Y) :- female(X),parent(P,X),parent(P,Y),\+ X == Y. 116 The instantiation pattern (-, +, ?) is an extension to‘standard’Prolog. There is no way to express "a list where the last element is c" as a (syntactic) literal in Prolog, so we have to resort to more Duplicate the elements of a list a given number of times. % your code here insect(fly). If this is undesirable, you have to ensure the third clause doesn’t succeed under One important difference is findall returns an empty list whereas bagof returns false/0 if there are no results for the input, making bagof usually the better choice for logical programming. ’This is still the case of the command line option --traditional is given. select(M, Y, X). intersection/3: True if Set3 unifies with the intersection of Set1 and Set2. The second rule states that two elements are consecutive in a list if they are consecutive somewhere in the tail Question: • Question #2: Detecting Duplicates Write a Prolog predicate has duplicates (x) that is true if list x contains duplicated elements that is at least 2 copies of an element). For example, calling the goal X is 3 + 4 will evaluate the right operand and attempt to unify the Lists Domains. Duplicates are removed. Prolog: Removing Duplicates. I'm having trouble getting a certain predicate to work. Hot Network Questions Does -iller have an implied meaning in French verbs? Is travel insurance required for an hour stopover in Paris, France Is it possible that mosquitoes have been laying Prolog Duplicate a word in list. Hot Network Questions What was the first "Star Trek" style teleporter in SF? What's the statistical historical precedence for generalisation beyond overfitting? I am trying to remove duplicates from a list while keeping the rightmost occurrences. Some systems provide genarg/3 that covers this pattern. Now available on Stack Overflow for Teams! AI features where you work: search, IDE, and chat. an element is an element. The implementation uses sort/2, which implies that the complexity is delete_unique([H|T],[H|Solution]):- member(H,Solution),!, When the second argument to delete_unque/2 query is a variable, this logical path will always be taken since Prolog will successfully unify the variable to [H|Solution], and member(H, Solution) will also always succeed in that case since Solution is subsequently variable. The following is based on my previous answer to Remove duplicates in list (Prolog); the basic idea is, in turn, based on @false's answer to Prolog union for A U B U C. It's permutation which does the work here, not findall. Eliminate consecutive duplicates. I don't know how to do it. The sort is stable, which implies that, if duplicates are kept, the order of duplicates is not changed. How to get reverse pairs of the list? 3. Hello I'm doing a project on prolog and still grasping with the language. Prolog Recursion skipping same results. Hot Network Questions Help identifying a board-to-wire power connector Does Psalm 127:2 promote laidback attitude towards hard work? The trouble I've been having is that after I move a non-duplicate to the other list, it's duplicate is no longer a duplicate so isn't moved into the list. So I tried to incorporate that into my remove duplicate method but I don't really understand prolog very well so it is not working. pl. Avoid data redundancy in Prolog. edit When done, you could remove unwanted pit/2, to get your db 'clean'. insect(fly). Prolog Syntax Prolog programs are constructed fromterms: constants, variables, or structures. Such that delete(X,L) deletes the first instance (from the head) of integer X from list L. For each element (excluding the empty list), the element is added twice to a newly built output list. Errors List is type-checked. I've tried to implement it using append but I'm quite new in Prolog and I'm a bit lost. 1) Define the double(X,Y) predicate, which is true if the list Y contains each of the elements X repeated twice. Prolog Beginner: Reverse List only once. that varies from run to run of the program; 2. In this case, there is nothing to do, so the body of the rule is empty as well. Note: I have read other stackoverflows, and I understand how to remove duplicates but what I don't understand is why my code isn't working. Modified 6 years, In SWI-Prolog there is the predicate sort/2 to sort lists. In fact by using member, if the list contains duplicate values, it will result in yielding the same list multiple times. I currently have a list of lists, in which the sublists have coordinates. unique([]). That produces two answers for the same call (Prolog “or” is inclusive). First example will just walk a list and duplicate it. Remove duplicate from list. So, if you have a list with some variables bound, you can say: nonvar_member(M, List) :- Creating lists do not include duplicates in Prolog. Removing duplicates from a list in prolog. However, if I put a cut in one, it wrecks backtracking. Hot Network Questions SearchKit columns to mailing tokens Why were the Sadducees convinced by Jesus' argument about the resurrection? What do the hieroglyphs say on Reapers mythic? Where is the inflection point here in this elbow chart? If i click on it, it only shows me that: append(+ListOfLists, ?List) Concatenate a list of lists. Possible duplicate of Prolog: splitting a list into two lists (unique items / duplicate items) – repeat. I do not want to delete the duplicate, I would like to figure out if there is an element that is repeated or duplicated and then have Prolog output 'yes' if there is a duplicate in a set or 'no' if there is not. For example a list that is [1,2,2,3,4,5,5,2] should return [1,2,3,4,5]. The elements in a list can be anything, including other lists. I try to make the code below working with the example query compress([a,a,b,c],S). combine(X,XX), then the tail. That give us this: list_set( [] , [] ) . The append/3 predicate can be used to split and join lists. How to code a prolog program that has same amount of elements. Commented Jan 28, 2019 at 12:58. It this case, since the head can be found elsewhere in the list, it's a duplicate and can be discarded. The result of the predicate should be as follows:?-no_duplicates_intersection([a,v,a,c],[a,a,a,a,a],L). /* This is the regular duplicate elimination that sorts the head element before checking for duplicates */ remove_dups([],[]). Returning a list: Prolog [duplicate] Ask Question Asked 9 years, 10 months ago. You are assuming that remv/3 returns a list, but it's not the case. I eventually put in this line above them: list_swizzle([], [], []):- !. Remove Duplicates while retaining order, Prolog. Prolog : how to detirmine if there are duplicate element in a list (not consecutive) 2. Prolog : get the opposite result. Removing unique elements from list in prolog. Removing duplicates from a I am new to Prolog and I am having a problems checking if two lists have exactly the same elements. In addition, the poem cannot have duplicate words. How to check if all elements in the list of lists are the same except one [Prolog] 0. prolog avoiding duplicate predicates. Prolog removing unique elements only. Modified 5 years, 4 months ago. Tags are associated to your profile if you are logged in. Removing duplicates in prolog. contained(X, Y) :- member(M, Y). Im trying to create a is_list(+Term) True if Term is bound to the empty list ([]) or a compound term with name‘[|]’ 137 The traditional list functor name is the dot (’. here. Prolog is not a functional language, so you can not type L+1 and expect it to be evaluated to the sum. Some additional list manipulations are built-in. That leads to the following clauses when broken down into each case: remove_dups([], []). Removing Duplicate Elements from List of Lists in Prolog. X = [a,a,b,b,c,c,c,c,d,d] Since Write a predicate set(InList,OutList) which takes as input an arbitrary list, and returns a list in which each element of the input list appears only once. Prolog: check against duplicates in a list. Lfront contains all the copies of X that are at the beginning of L, including X; Lrem is the list of the rest of the elements. findall finds these two routes, etc. As hinted in Carlo's answer, L+1 is a Prolog term with two arguments, L and 1, whose functor is +. 4. remove_duplicates([Head|Tail], Without):- is_member(Head, Tail), remove_duplicates(Tail, Without); remove_duplicates(Tail, Head). How can I prevent duplicates in prolog. Remove duplicate from a list but not returning two same results in SWI-Prolog? 2. If you are trying to represent some kind of elementary classification, you could use library, and go with a list of Key-Elements. I need to get [a,b,c]. how can I write two predicates that are described below. Related. 3. Unfortunately I dont know how to handle recursion call properly. As a result, we cannot use type polymorphism that involve both atoms and lists. prolog list of how many times an element occurs in a list? 18. Creating lists do not include duplicates in Prolog. Some Prolog systems include predicates which would make it quite easy, I don't think SWI-Prolog does. Predicates express relations and are always true or false. The source list is not empty, and the head of the list is duplicated in the tail of the list. Equivalence is based on ==/2. it doesn't matter what the list's element is. Making a reverse list. Prolog: replace an element in a list at a specified index. zip function in Prolog. Intersection of two lists without duplicate elements in Prolog. Moreover a union implementation( or other set-predicates) should also have the following properties in Prolog: Handle duplicates. Finding number of unique elements in the list. Prolog function returns duplicate. But for situations where you don’t need to check for duplicates, the difference-list approach (which requires logical variables to work) is a big win. If I try to find all the sisters using a query like this: ?- sister(X,Y). Thus, think in terms of describing when the relation ps/1 holds for lists of lists: It holds for the empty list []. Prolog meta-predicates: applying a predicate to lists, passing a constant. In your 25 you hit the issue of duplicates: union([a,a],[a],X) produces X=[a]. Another way of removing duplicates is Today's post is about problem 14 from the list of 99 Prolog problems (see here): (*) Duplicate the elements of a list. 142 Contributed by Richard O'Keefe. Build a list of distinct members of the input list Y which unify with input member X; Then for each X from the list built on 1) discard this element from the input list to get the output list Z without member X. SWI-Prolog -- list_to_set/2. If one of the lists have at least an element more than one times then this element should be counted only one time. Unlike arrays in other programming languages where we can directly access any element of the array, prolog lists allow direct access of the first element only which is denoted as Head. In addition, the case of lists with different lengths should be handled. The problem was that if the both of the first two arguments are the empty list, the first two statements would both be used, returning the same answer. The complexity of the implementation is N*log(N). Then we define the general case - a non-empty list. Handle cases where at least one argument is not instantiated. Is true if ListOfLists is a list of lists, and List is the concatenation of these lists. What message do I want to convey to you? You can describe what you want in Prolog with logical purity. A common idiom in prolog is to use a worker predicate with an accumulator. The second clause processes the case when your list has at least one element. The predicate should be of the form delete(X,List). For example, for the question % recursion is the proper Prolog way to do cycles placePit(0). Prolog check if list X has any duplicates. List may contain variables. In order to use a difference list, you need to keep track of the "hole" in the list (in this case, its tail). But sort(List1, List2) succeeds if List2 is the sorted list corresponding to List1 where duplicate elements are merged. Second you have to decide what happens if h is not This library provides commonly accepted basic predicates for list manipulation in the Prolog community. See also Prolog, filter duplicates, while keeping list order. dicts_to_same_keys ( +DictsIn, :OnEmpty, -DictsOut ) DictsOut is a copy of DictsIn , where each dict contains all keys appearing in all dicts of DictsIn . How to return duplicates from list in Prolog. The rules has the following meaning: for a list [H|T], the list [H|X] is the initial one without doubles if there is Of course, you probably should switch representation to lists, or will have an hard time with the remaining of your program. an asterisk after a domain means "List of that domain". I just started learning prolog so those are probably newbie questions. The pairs must occur in strictly List operations in prolog [duplicate] Ask Question Asked 5 years, 4 months ago. Step 1 is done with setof(X, member(X, Y), L) and it works in two ways. There's just a few cases: The source list is the empty list ([]). You should try to modify the second rule: remvdub([H|T], [H|X]):-remv(H,T,T2), remvdub(T2,X). SWI-Prolog version 8. Learn more Explore Teams I am trying to make use of prolog predicates and find middle element of a given list. List must not contain duplicate keys. The last findall then runs subtract over the sublists, removing the duplicaates from each one. Assuming we want an empty list if the input is an empty list, the first clause below sees to that. See also ord_union/3 Seems like something like this would be the easy way: intersection( Xs , Ys , Zs ) :- sort(Xs,X1) , % order and de-dupe the 1st list so as to produce a set sort(Ys,Y1) , % order and de-dupe the 2nd list so as to produce a set merge(Xs,Ys,Zs) % merge the two [ordered] sets to produce the result . The first clause processes the base case, when the list [] is empty. The M setof(X, goal(, X), Xs) finds all the X values that are a solution to goal(, X) and puts them into the list Xs (without duplicates); member(X, Xs) gets the results one-by-one on backtracking. If exists/2 would also 'return' the list T after having removed the duplicates found, then we could use the cleaned list for the recursion, and the task would be complete. The implementation is in C, using natural merge sort. One way to ensure that the returned list does not contain duplicates in Prolog is to use a predicate that removes duplicates from a list. Removes Duplicates: How to remove duplicates from a list in SWI-Prolog? 4. I have this code: Same with the duplicates - your set equality predicate should disregard any. Prolog: eliminate repetitions in query. Even the syntax is not correct - however this is my I'm just picking up Prolog, so I don't know the correct terms, but I think the logic goes as following: The rules for remove(X,L,T) is straightforward, it defines T as a list with X removed from L. Instead, prolog keeps on providing other answers. Basically what I want to do is have this as inputs and outputs: We traverse the list element by element until we reach the last element, i. Commented Jan 28, 2019 at 12:51 @GuyCoder i see now your possible duplicate, but i dont want use a standard between or numlist. How not to show if there is same result occurs more than once- Prolog. 2. Prolog: How to eliminate duplicates of list of elements without changing the order of the elements? Load 7 more related questions Show fewer related questions Sorted by: Reset to default Know someone who can answer? Remove adjacent duplicates in a list with Prolog. The solution works for ground terms. Prolog: How to eliminate duplicates of list of elements without changing the order of the elements? Load 7 more related questions Show fewer related questions Sorted by: Reset to default Know someone who can answer? Prolog: How to eliminate duplicates of list of elements without changing the order of the elements? Hot Network Questions Why does the Fisker Ocean have such a low top speed? How does "attempting to influence a public servant by means of deceit" affect political activity? Which other judges, in the Anglosphere, pinpoint paragraphs with ¶? True if Elem is a member of List. the empty list. • Numbers are strings of digits with or without a decimal point and a minus sign. So, if you have a list with some variables bound, you can say: nonvar_member(M, List) :- The downside to this approach is that you wind up with a list rather than Prolog generating different solutions, though you can recover that behavior with member/2. insect(ant). I. I'm fairly new to prolog and I'm currently reading through a book which is giving me practice examples to code. Commented Oct 16, 2015 at 22:49. Question: 3. Remove duplicate elements from list. Remove duplicates in list (Prolog) 0. But there is also a path from A to B via some C with the length 13. Here is an example poem: uga buga ru batta hatta nu fitty pitty witty ditty garra farra tu It will help One way to eliminate the duplicates is to use the standard recursive process for removing duplicates, but rather than checking equality directly through unification, change the code to try unifying sorted lists. There’s just one step to solve this. Errors domain_error(unique_key_pairs, List) if List contains duplicate keys [det] ord_list_to_assoc(+Pairs, -Assoc) Assoc is created from an ordered list Pairs of Key-Value pairs. % Empty list is empty list with dups removed remove_dups([X], [X]). Prolog: reverse list (sublists included) 5. Remove duplicates in list (Prolog) 1 How to avoid repetition in prolog. So the answer is "yes, you just need to write a predicate combination such that calling combination([a,b,c,d,e,f,g], List, 5) will produce all 5-element sublists of [a,b,c,d,e,f,g] as separate answers". The problem was in handling the case H=[H1] when member(H1,L) so added last clause, though this may leave empty lists in the final list for example in your last query all the elements from [1,3,4] must not be included leaving an empty list in this solution, so I think the easiest way based on the above solution was just to remove empty lists using another predicate. It T is a type/domain then T * is the domain of lists containing T elements. I've written so far prolog program that finds Hi Friends,This YouTube channel is created for Education Purpose,If you are interested in this field Subscribe My channel for getting more video like this. e a difference list is always a pair of two terms, one being a list with the "hole" and the other being the "hole" itself. How to removed repeated elements from lists in prolog? 2. I want the code to: Write a hasDuplicates (List) rule that returns true if a list has duplicate items. For example from duplicate([a,b,c,a,b,r,d,c], R). combine([],[]). Step-by-step: We combine two predicates memberd/2 and non_member/2 to one, memberd_t/3, which uses an additional argument for reifying list membership into a truth-value (true or false). Prolog avoid generating same lists twice. There are roughly two options. Duplicates are removed. 3. Consider the possibilities. Prolog checking if 2 lists have same number of elements. If you consider (A. So first, you need to make a decision about the empty list. 5 Prolog: Removing Duplicates. deprecated There are too many ways in which one might want to delete elements from a list to One should note that to append an item to a prolog list requires traversing the entire list, prepending is a trivial operation, due to the structure of a prolog list. Follow Duplicate solutions. 140 Contributed by Richard O'Keefe. "Therefore, use prolog-dif, i. Here is my solution: How to remove duplicates from a list in SWI-Prolog? I need to write a predicate remove_duplicates/2 that removes duplicate elements form a given list. sibling(X,Y):-parent(Z,X),parent(Z,Y). And say I have a DB full pairs that Prolog can figure out are sisters. for example I ask Prolog's query: ?- copy_list([a,b,c, Why not just take the smaller list, duplicate it into a new list with each item twice then generate the permutations of that list and if one matches the other list it is true? Prolog - list contains 2x element X. Modified 3 years, 5 months ago. Prolog list membership, multiple results returned. What I was saying in my comment was : I want two items from the list L wich are not in the same place so. List1: [[1,4],[1,6],[6,8],[8,10]] Skip to main content. How do I delete all but duplicates from a list in prolog. Prolog, filter duplicates, while keeping list order. The first entry of that "inner list" is H, the head of the input list (which also equals the second entry of the input list); the tail of the "inner list" is TFR, which is the head entry returned from the recursive invocation. In your graph there is a route of length 6 between two specific nodes A and B. This says "empty lists are unique. This problem has been Prolog, filter duplicates, while keeping list order. The first rule says that [X,Y] represent two consecutive elements in a list if they are the first two elements in that list. B) and (B,A) as the same, use A @> B instead of not (A=B) (which you better write as \+ A = B or even To remove duplicates from a list in Prolog, you can define a predicate that checks each element against the rest of the list and removes duplicates as it finds them. See e. remove % recursion is the proper Prolog way to do cycles placePit(0). Variables are strings of characters beginning with an As per my understanding, you need to replicate list without using same reference to perform some operation in future. Then it'll notice that Parent = mona and give them to you a fourth time. Constants can be either atoms or numbers: • Atoms are strings of characters starting with a lowercase letter or enclosed in apostrophes. You're saying that repeated can be called with any one-element list as its first parameter, and it doesn't matter what value appears in that list, the relation will be true. Prolog’s lists: –start with ‘[’ –end with ‘]’ –separate elements by ‘,’ In Prolog, functions work by recursion rather than iteration. Write a PROLOG predicate, eliminateDuplicates, which, given a list L, returns the list without any duplicate elements. Prolog : how to detirmine if there are duplicate element in a list (not consecutive) 1. For example, the list [1, 1, 1, 2, 2, 3] gives [1, 1, 2] as the output, as the last one and two aren't considered duplicates as they're no longer members of their tails, and I can't check to And in such cases, there is nothing to "repeat" yet: We start from nothing, and ask Prolog what solutions there are in general. How to remove even numbers in List using Prolog. If Key is the integer zero (0), the entire term is used to compare two elements. You want random names? Describe what such a name looks like, etc. Leave only one copy of the repeated elements. Remember that in Prolog values are immutable so to change a list you need two variables, one for the original list and one for the changed list. Example: double([a,b],[a,a,b,b]) is true. A set is defined to be an unordered list without duplicates. Here is an example of how this can be done: First, define a predicate remove_duplicates/2 that removes duplicates from a list: 1 2 3 Why not just take the smaller list, duplicate it into a new list with each item twice then generate the permutations of that list and if one matches the other list it is true? Prolog - list contains 2x element X. Creating a set from a list in Prolog. : [1,2,3,1,2] is transformed in [3,1,2] It's one of my first tries in Prolog and I don't understand what am I Returning a list: Prolog [duplicate] Ask Question Asked 9 years, 10 months ago. list_to_set([3,1,2,3,4],X) gives X = [3, 1, 2, 4]. A prolog predicate checks if an element occurs at least twice in a list. In this answer we improve the logically pure code presented in this earlier answer. Should return the list with 5 removed from it List=[2,3,4,6,7,8,9] The correct way to check if a list is a set in Prolog is to sort it, removing duplicates, and check if its length is still the same. How to make predicate for simple Prolog database. 138 In versions before 5. Stack Overflow. Prolog program to create a list with first duplicate elements. % end of recursion (we call it 'base case') you should call as ?- placePit(3). X = [a,a,a,b,b,b,c,c,c] Raw. Try to follow Carlo's suggestion and use the is/2 predicate to force arithmetic evaluation. Counting Sublist Elements in Hi, I want to use prolog to make One Hundred Years of Solitude 's family tree, and when i try to search result, I find there are the duplicate part? and puts them into the list Xs (without duplicates); member(X, Xs) gets the results one-by-one on backtracking. It holds for the list [L|Ls] if our initial predicate (p/1) holds for L, and ps/1 holds for the I am trying to create a predicate that removes duplicates from a list while maintaining its relative order. pez artfzxhh fus ayghyxg fikyyeq yueaux feoqj feewjj zlswjj gxcp