Python compare two lists and return differences. But it depends on the outcome required.

Python compare two lists and return differences g. How to find the difference between two lists in Python using the set() method; Python find non-matches I have two lists: listOne = ['John', 'James', Daniel', 'Peter', 'Luke'] listTwo = ['Daniel', 'Peter', Kate', 'Jenny'] I want to compare these two lists and return the non matches, and if need be, save this to another list, so the output should be: I'm trying to compare list_A: 60 elements against list_B: ~300,000 elements, and return a count (in the form of a list) of the number of elements in list_A that appear for each of the elements in list_B. I'd like to compare two lists. You can convert the lists to sets and run the usual set operations such as difference or symmetric difference. ndiff(open('a. isin(dif_list))] You can try to vectorized the operations instead of evaluate the scores in a loop. In this way comparing two strings is just a matter of object address, constant, no matter how long is the string – fabmilo. compare two lists to get non matching elements. You can use enumerate by saying for i, ch in enumerate(seq1) instead. join(missingOnMaster))) print("22Missing on {0} in store firewall: \n\t{1}". To check if the two lists are similar, use the == operator. You also have a problem because you return before you print. Collections that support order comparison are ordered the same as their first unequal elements (for Why should I use sets in the domain I provided? sorted(a) == sorted(b) seems to me to be more simple and more readable. In my program I've to compare two lists which are in two different files like the ones below: list1=[1,2,3,4,5,6,7,8,9,10] #this list is in file 'a. """ ??? An usage example is the following: string1=""" Usage: trash-empty [days] Purge trashed files. I need to compare two lists without taking their order into account: list_a = ['one', 'two', 'three'] list_b = ['three', 'one', 'two'] when I try to compare them, it returns False: >>> list_a == list_b False Both lists have many elements, what would be the optimal way to compare them? I want to compare the two list element wise and expecting the result as given below:- How can I compare the values of two lists in python? 3. 1 1 1 silver badge. If you try and use a list as a dictionary key your code will not run. Follow edited May 23, 2017 at 11:51. We’ll explore different methods to achieve this comparison. 7. Book series: starship officer returns to the academy where he trained with gardener in martial arts Computing the “real width” of a horizontal or How can I compare two lists in python and return not matches. In my case, the first CSV is a old list of hash named old. In Python, to find the difference between two lists, you can use the set subtraction method, the . There also isn't a built-in dictionary analogue to frozenset. Example in pseudo code: j=0 for x in mylist #loop through the l My exact situation would be a list of very similar strings, let's say 10 of them, in which I want to use the first item in the list and compare it against all the others one after the other, placing those differences (i. Assume we have a file called unicode. unique()) if x not in list(df2['City']. This checks if items in one list are present in the other. E. 7 67. list1 and list2 above returns 1, but so does list1 and list3, when ideally that should return 2. Here is my code : Linked to this How can I compare two lists in python and return matches. I want to know, if those sequences are similar (order is not important). Compare . Examples and illustrations would be very helpful. How to compare two dictionary elements which has list of dicts using python. Lists are of different length and they are equal up to the length of the shorter list. 9 . right_only + dcmp. Comparing lists in Python . In Python 3, though, comparing objects of different types is disallowed in many circumstances -- for example, you can't compare strings to integers -- so if you will have The following code compares three lists, motherList fatherlist and sonList, checking to see if every value in sonList is represented in either motherList or fatherList once. html and followers Objects of different types always compare unequal in python (unless you override __eq__ to make it otherwise). Compare two lists to find identical values, return the missing value. Performance-wise don't expect that any equality check will beat another, as there is not much room to optimize comparing two elements. I think this one is golde. If the input arrays don't match the criteria you'll need to convert to the set format and invert the transformation on the result. 3 - 2. Taking two lists and comparing for similarities. Python - compare two lists' values AND lengths Implied warranties vs. In [14]: df. You can then paste your copied lists or you can upload the exported following. This is what I tried - unsuccessfully. Watch this video on Youtube to see how it can be done. 0 import operator, itertools as it def seq_cmp Determine if 2 lists have the same elements, regardless of order? Inferring from your example: x = ['a', 'b'] y = ['b', 'a'] that the elements of the lists won't be repeated (they are unique) as well as hashable (which strings and other certain immutable python objects are), the most direct and computationally efficient answer uses Python's builtin sets, (which are Here's a one-liner to get a list of all comparisons. One way to compare two lists in Python and return the matches is by using list comprehension. how to calculate the difference between lists. Thank you the property1,property2 that i have named are different from the ones that are actually in the file. readlines(),open('b. setmember1d() that works on sorted and uniqued arrays and returns exactly the boolean array that you want. The tricky bit is that the values can be ints, strings, lists, or dicts, so it needs to be recursive. Here, we will use both methods in It will return: > [4, 8] The above solution will return a list with the indexes in sorted order, won't create any unnecessary intermediate data structures and it will work on Python 2. mx = max(b) print(all(x >= mx for x in a)) For pairwise you can use enumerate: print(all(x >= b[ind] for ind,x in enumerate(a))) and simply returns either the first or the second operand, based on their truth value. I used a set here: I want to compare these two lists and identify the values which are duplicated in the second list regardless of if it starts with a capital letter or a lowercase letter. extractOne(row['inp'], row['ref']), axis=1). 0 1. You could use a Counter: from collections import Counter the with two lists, say. 6. def compareList(motherList, fatherList, sonList): count = 0 for x in sonList: if x in motherList and x in fatherList: count = 2 elif x in motherList or x in fatherList: count += 1 if count >= 2: ans = Gives you a terser output (the . Probably your return needs to be moved down and unindented. [True, False, True, True . The conversion to numpy arrays and the function call overhead makes this approach (using the lists in the OP) 3-5 times slower than any pure-python approach. lower() will work most of the time, but indeed doesn't work in the situations @tchrist has described. It should be explicitly passed everything it needs and return a result, not implicitly receive information and change something outside itself. comparing two list with different format. Method 1: Using the Set Data Structure for Comparison. Learn to compare if two lists are equal, find elements that match, get the difference between 2 lists, compare lists of dictionaries, and list of strings. Here are two possible approaches: Method 1: Using List Comprehension. each of them has their own meaning in python: < means the date is earlier than the first > means the date comes later == means the date is same as the first So, for your case: import datetime date = When I compare these 2 strings, the value I get is False. So I tested it: You have 2 lists of strings with contents of your choice. Follow answered Aug 9, 2016 at 23:01. I have two lists that contain many of the same items, including duplicate items. x replace xrange for range. small substrings) into a list for collection. As best I can describe it, I have two lists of strings and I want to return all results from list A that contain any of the strings in list B. in . I have two lists of strings and I'm looking for mismatches between the two. For example, set(b) - set(a) evaluates to set([7, 8, 9]). 7, it says that no such modules are defined. For sorted lists, without python special built ins, an O(n) solution This approach, df1 != df2, works only for dataframes with identical rows and columns. I don't have any idea Maybe something like this: a = [1,1,1,1] b = [1] c = [1,1,1] d = [1,1,1,1,1] e = [1,1, I have a nested list and another nested list which is a subset of the first list: lst = [[1, 2], [3, 4], [1, 2], [5, 6], [8, 3], [2, 7]] sublst = [[1, 2], [8, 3]] How What I want to do is -- if crucial has a key (in this case, eggs) in the dishes, it will return 2. transform('func') returns us a vector with the same length as the original DF with applied func. This is because zip truncates the comparison to the shorter list, meaning the extra elements in the longer list3 are ignored. difference this In this tutorial, you’ll learn how to compare two lists in Python Programming Language and return the matches and differences between them. Example: Will the lists being compared be of comparable sizes or very different? Do you expect most lists to match or not? only that the ordering is the same for both lists. Improve this question. > i:1 > 'c' dict value is different: 0. After watching the first 2 minutes, just use following. append(element1) return differences “` The space complexity of this approach is O(1) as we are only using a single list to store the differences. format(common,"\n\t". i. You could use sets, but as has been pointed out need to be careful with duplicates getting lost. I would write a function that prints the differences between two multiline strings in the unified diff format. Another option would be to use the conditional part of the By what logic do you define "the right index"? Why should "zebra" go between "cat" and "dog"? I strongly recommend editing your post to show 2-3 additional examples that illustrate your specification. [c1 for c1, c2 in zip(l1, l2) if c1 != c2] Note that there's a bit of an assumption that the two lists have the same length. What's wrong with this string I have two 1D Tensorflow tensors and I want to compare them elementwise and create a new tensor recording the indices at which they differ. Python compare 2 lists with duplicates. . This tutorial explains how to compare two lists in Python and return non-matches elements using the different methods. "no returns I want to compare this 2 lists and get smth like: [True, True, False, False, True] The problem which I have is that lists must have a same length. My code returns a list with True or False if the items at the same index of the two lists are the same. "df1": id Store is_open 1 'Walmart' true 2 'Best Buy' false 3 'Target' true 4 'Home Depot' true "df2": Compare Each Element of Two Lists in Python; How to Compare Two Lists in Python; Compare Two Lists & Return Matches & Differences in Python; Python Programming Tutorials . first= (1,2,3,4,5,6) last=(6,5,4,3,2,1) I need to compare the corresponding values only. 9 43. Basic list comparison in Python involves checking whether two lists are equal or not. Comparing 2 dictionaries based on values for matching keys. viewkeys() & set(lis)} # python 3: n = {k: d[k] for k in d. The cmp() function is used to compare two In Python 2. Finally you'll get the best match name and score in ref_list for each name in inp_list. It has less duplication at the cost of a dirty trick to stay within the rules of the exercise: def compare(a, b): if isinstance(b, list): # Let's cheat and change the meaning of the parameters. Hi I would like to compare two list that are different lengths and print a sorted table with items that are missing in each table. left_only + dcmp. How to compare individual characters in two strings in Python 3 [duplicate] Ask Question < b[i]: s+=str(a[i]) else: s+=str(b[i]) return s print compare ("seven", "eight") Output: eegen The one-line version of this In Python, You can get the similar items from two different list using set. For comparison,first we will check if the length of the lists are equal or not. > i:1 > 'a' dict value is different: 46. compare different keys in two lists of dictionary in python. 2. It seems simple enough, but I believe I must be messing some type of syntax somewhere. Compare Two Lists of Strings in Python (5 Examples) This tutorial shows how to find similarities and dissimilarities between two string lists in Python programming. OP's question doesn't impose any restrictions on what the lists may contain, and assuming only 0 and 1 doesn't simplify anything. I get an output file of both lists combined into one long list The function return those two list so because there are different in two element and every thing is the same, but if it compares: If c=[0, 2,3,33,4,66,9] And b=[0,22,2,3,4,77,9] The function should give me false results because the two items in different positions in the list Comparison Ordering. Because both lists are not empty, x and y simply returns the second list object; only if x Here is my solution to a similar problem comparing two strings based on the solution presented here: result += delta * no_match_c n_diff += delta return (result, n_diff) Setup the two strings for comparison and call the function: Count letter differences of two strings Python. In this article, we will understand how to compare two lists in Python. As a result, the list contains the same number of elements, so it is equal. 7, I have two lists of integers: x = [1, 3, 2, 0, 2] y = [1, 2, 2, 3, 1] I want to create a third list which indicates whether each element in x and y is identical, to yield: z = [1, I have two lists: L_1 and L_2 containing strings. Compare items from two lists in Python. union() method, or the numpy function setdiff1d. Compare Value in Dataframe and List. if x not in mmeList2: result. : list 1 [('EFG', '[3,4,5]'), ('DEF', '[2,3,4]')] and list 2 [('DEF', '[2,3,4]'), ('FGH', '[4,5,6]')] I would like to compare the two lists and recover those nested lists which are identical with each other. x) python; comparison; Share. c = ['hi'] since the first list has an extra 'hi' What is the quickest (and least resource intensive) to compare two massive lists (>50. By the end of this guide, you'll have a comprehensive understanding of how to compare lists in different scenarios and choose the most suitable method for your needs. x you can use same expression, just map function in Python 2. compare two lists (python) 2. I searched in internet, but I can not to find what I need. I want to check which items in the first list are not in the second list. The contents of each list item is either 1 or 0 (single integers), and the amount of items in each list will always be 307200. All(). txt containing the two strings Σίσυφος and ΣΊΣΥΦΟΣ. format(common, "\n\t". Important: Start by selecting "Instagram followers" to remove unwated data like dates and profile picture texts from the lists. Comparing two list and getting a new list in python. Result should look like this: Size(15) Check if the two lists are similar. " python; list; compare; Share. 1. e. Something like that: def print_differences(string1, string2): """ Prints the comparison of string1 to string2 as unified diff format. >>> a=[1,2,3] >>> b=[2,3,4] >>> set(a) & set(b) {2, 3} >>> To get this output in the list format, Just Type as follows >>> list(set(a) & set(b)) [2, 3] Comparing 2 lists in Python refers to determining whether the lists are equal or have any differences. for list1 = [1, 2, 3] and list2 = [1, 2, 4] it returns [True, True, False]. 6 or older: n = dict((k, d[k]) for k in lis if k in d) # python 2. I've tried the following method: This way it returns the original values while comparing the lowercased. Which seems If you want to check if two arrays have the same shape AND elements you should use np. python; list; set; Share. Trying to compare the similarity of 2 lists, to see how many times the 2 lists match. Hot Network Questions Errors while starting vite + react Can Bob send a stone into Alice's future? @ribamar the question is "Comparing two dictionaries []". Two of the most popular methods are set() and cmp(). If they have different length, zip will only return the n tuples where n is the min length of the two lists. I edited your code a bit as follows: if missingOnMaster and missingOnStore: print("11Missing on {0} in master firewall: \n\t{1}". This function has a bug: if you compare two empty Compare two lists and return non-matches elements in Python. unique())] returns: ['San Franciso', 'Boston'] You could then get a dataframe with just the rows that are different: dfdif = df1[(df1['City']. In fact, all dataframes axes are compared with _indexed_same method, and exception is raised if differences found, even in columns/indices I noticed a piece of code recently directly comparing two lists of integers like so: a = [10,3,5, ] b = [5,4,3, ,] if a > b: which seemed a bit peculiar, but I imagined it would return True if all of list_a's elements are larger then list_b's and False if each element is equal or list_b's elements are larger then list_a's. This would fetch either unique index elements or not rather than a list of True or False. As True == 1 and False == 0, we just sum this to get the number of differences. Python - comparing two nested lists and writing a third nested With python as the easiest language available it is pretty easy to compare dates in python the python operators <, > and == fit wonderfully with datetime objects. One has Product Titles and other one has brand names ( may be one word or more). l1 = [1,1,2,3,4] l2 = [3,3,4,5,6] for examples' sake, can use fed into a Counter each The reduce() and map() The map() function accepts a function and Python iterable object (list, tuple, string, etc) as an arguments and returns a map object. Ask Question Asked 13 years, 9 months ago. But as long as the first list has the required items defined in the second list, the function would return a true value. Comparing elements in different lists python. 7; or ask your own question. So far that was my approach: equals = [] for quote in l2: for quote2 in l1: Thank you for your understanding. txt" diff = difflib. python; python-2. I want to compare 2 lists and get the ids which have different value in list2. Then call df. If they are not Identical, I want to print the difference on the screen. There are a lot of properties within the xml file. 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 When I simply used XOR between the 2 lists, it also only returned "e. So far I have tried this I need to see if 2 items from a list appears in another list, and if they do, compare the items by their position in the other list. Here are details: A = ['dataFile1999', 'dataFile2000', 'dataFile2001', 'dataFile2002'] B = ['2000', '2001'] Matching strings when comparing two lists in Python. it will return the same string object. html and followers. Comparison of two If you actually want to compare every element in a against b you actually just need to check against the max of b so it will be an 0(n) solution short circuiting if we find any element less than the max of b:. Besides, The reduce() method implements the given function to the iterable object recursively. To be the whole of list y needs checking each time for each i in h. How do you compare 2 lists and return the difference? (difference function in python does not compare two lists in python and return indices of matched values. Union is list1 + list2. remove(element) I'm getting or slightly modified to return list: list((set(x) | set(f)) - (set(x) & set(f))) #if you need a list You can find unique elements in two lists python Numpy has a set function numpy. After a little bit of investigations I realized that the comparison returns another list with booleans to check if the content is different or not. x returns a list so the list() is not required. Vote my answer down if you like :-) – def has_differences(dcmp): differences = dcmp. – Matthias. I have used the below code and getting 36 results as the 1st element in first is comparing with all the six elements of last list. The compared lists aren't going to be huge - each one will have at most 10 items, and this comparison is going to be made only a few times. An element x is in the intersection if x is in list1 and x is in list2; you want to exclude such elements so the condition should be reversed: not (x in list1 and x in list2) that is equivalent to x not in list1 or def differences(a, b): if len(a) != len(b): raise ValueError("Lists of different length. Treat lis as a set instead, so you can use dictionary views and an intersection: # python 2. > i:0 > 'b' dict value is different: 100. The 'invalid dict' above with list keys is not valid python code - dict keys must be immutable. Equality between lists is typically defined as having the same elements in the same order. The lists Using Basic Comparison with in and ==. columns is a list indeed. Say we have two different lists: list1 = [1,2,3,4,5,6] list2 = [2,4,5,7] If we were to calculate the difference between list1 and list2, we would find that list1 contains [1, 3, 6], while list2 doesn’t. How to compare values of two dictionaries that have The two lists are identical. Otherwise, it returns False. 0 99. (Python 2. a = "comentar" b = "️comentar" print(a == b) # False The first character is different (although it looks identical to the naked eye) Try. They won't be in order, but here's the tricky part. I am using an lxml parser to try to compare the two files and to print out the difference between them. Comparing two lists in Python. The application of VBA Macro is also explained. I want to compare both of them and get all rows that have different values of any column. Lists are considered true when not empty, so both lists are considered true. The simplest way to check for common elements between two lists is to use in within a for loop. I have two list, first one with names only and second one with names and values corresponding to names. With Python 2: I wish to compare to nested lists of unequal length. To be able to give to the Assert a unique Boolean not a list of booleans – I have two lists: l1: 38510 entries l2: 6384 entries I want to extract only values, which are present in both lists. For Python 3. how do i compare 2 different string lists and return the difference if one is bigger? 2. Compare 2 list and get difference. values()]) Assuming I haven't overlooked anything, you could just negate the result if you wanna know if directories are the same: Python - Compare two lists in a comprehension. txt'). I think you're confusing == with other so-called rich comparisons (>=). == in this case does an element-wise comparison of the two lists and returns if all their elements are equal and the number and order of the elements is the same. The lists aren't large, about 5 elements. I am interested only in a match between the first element of each sub list. If the lengths are not equal, the lists will be I have two nested lists, each nested list containing two strings e. For instance, I have two 2-dim lists with 0's and 1's ,and I want to create a function that would return True if a 1 is in the same location in both lists. It’s also known as a sequence, which is an ordered group of objects that can contain objects of any data form, including Python Numbers, Python Strings, and for a program I'm writing, I have two lists at the end that I need to compare. I know how to iterate over the list of lists, but I do not find the way to create a list of lists for "result". > i:0 > 'd' dict value is different: 48. If multiple brands exist in a single product, they will all be listed in the returned list. If all elements are equal and the length of the lists are the same, the return Comparing two lists efficiently can often be achieved with the set data structure in Python, which allows for mathematical set operations such as union, intersection, and One of the simplest and quickest is: BONUS! If you want an intersection (return the matches): This is significantly faster than iterating through both lists as per the chosen answer. I'm trying to compare two lists of integers, each the same size, in Python 2. Getting differences between two lists (not just comparison) 0. For example, I might have one list like this: l1 = ['a', 'b', 'c', 'b', 'c'] and one list like this: l2 = ['a', 'b', 'c', 'b'] Comparing these two lists I would want to return a third list I'm using Python 3. Use a loop that goes through the lists and compares the lists elements and displays only the list elements that duplicate (the element exists in both lists). Imagine list1=[1,2] and list2=[2,2]. Unfortunately, collections. To actual. Using set, as in gnibbler's answer, works for lists containing any kinds of immutable elements -- arbitrary integers, floats, strings, tuples. 0. In this case only ('DEF','[2,3,4]') would be returned. 7: n = {k: d[k] for k in d. Compare 2 lists and return index and value to a third list. In other words, everything that was added, removed or changed. Modified 1 year, 11 months ago. 7 and up: n = {k: d[k] for k in lis if k in d} “`python def compare_lists_brute_force(list1, list2): differences = [] for element1 in list1: if element1 not in list2: differences. The set() function creates an object that is a set object. Therefore you are not comparing dictionaries. Depending on how big your old and new lists are, a set comprehension would work a bit more quickly, but that speed would be nullified by my sorted + itertools. Using numpy on small lists isn't exactly "lightning fast". Free Excel Courses. 000 items) and as a result have two lists like the ones below: items that show up in the first list but not in the second; items that show up in the second list but not in the first I have 2 files called "hosts" (in different directories) I want to compare them using python to see if they are IDENTICAL. The result of comparing two lists using <, <=, >, and >= is determined by the following rules:. Books Learn HTML Learn CSS Learn Git Learn Javascript Learn PHP Learn python Learn Java You note that I added result2 because #if string 2 is longer than string 1 then you have extra characters #in result 2, if string 1 is longer then the result you want to take #a look at is result 2 result1 = '' result2 = '' #handle the case where one string is longer than the other maxlen=len(str2) if len(str1)<len(str2) else len(str1) #loop For Python 2. groupby approach below (as sorted returns a list): Compare two lists using sort() method. The following also works for an arbitrary number of lists, not just 3, which does seem to be part of OP's zip the lists and return the test (which returns a boolean as outcome): You can try with below definition if you would like to compare lists with different size. print([ord(c) for c in a]) print([ord(c) for c in b]) Python, comparing identical strings return False. I'd like to find elements in the first list that don't have a corresponding entry in the second list (order doesn't matter): a = ['hi', 'hi', 'bye', 'hi'] b = ['hi', 'hi', 'bye'] So I would like the output to be. ") return sum(i != j for i, j in zip(a, b)) We loop over the lists together using zip() and then compare them. To check whether two lists contain the same elements or not, we can use the sort() method to sort the elements of the lists first. Let's dive into some common scenarios and the corresponding Python code examples. In this Python programming tutorial, you have learned I have two list. 1 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 Here's an alternative answer. If the first operand is considered false, it is returned, otherwise the other operand is returned. Improve this answer. How can i do that. 4. Ask Question Asked 12 years, 8 months ago. You can observe how the extra element in list3 was ignored and relatedly, the same output was returned. You can either create a subclass of dict with your own hash method, or do something like this: Modified user3's code to make it even better. To compare two lists and return the matches, you can use the built-in intersection() method of the set data type. How to compare two lists and get the indices of new values. I misunderstood the question. It works fine apart from when the second list contains duplicates. In python3, you can't use rich comparisons on When you say for i in seq1 you are iterating over the characters, not the indexes. If we The desired output would be a clear indication of similarities or differences between the two lists. compare two lists in python and return indices of matched values. readlines()) Comparing two lists is faster (and more memory efficient) than converting both to tuples. transform('first') Out[14]: 0 100 1 100 2 200 3 200 4 300 5 300 Name: C, dtype: int64 In [15]: df Python won't allow you to use a dictionary as a key in either a set or dictionary because it has no default __hash__ method defined. I already tried to iterate over each element of list1, and by comparing with list2, create a new array appending each element. array_equal as it is the method recommended in the documentation. Compare two files for differences in python. That will give you the values which are same in the two different lists. Comparing two lists efficiently can often be achieved with the set data structure in Python, which allows for mathematical set operations such as union, intersection, and difference. At the end the first list may have more items than the second list. ]. Here's an example: Short answer: The most Pythonic way to check if two ordered lists l1 and l2 are identical, is to use the l1 == l2 operator for element-wise comparison. Comparing two lists in Python and returning the matches can be done using several methods. And that's why I have to use the . I have two lists of different sizes. I am partially able to accomplish this and print the values that are Python comparing three lists with different lengths. csv and the second CSV is the new list of hash which contains both old and new hash. I want to compare a to b and then return a list of elements in a tha I'm in need of a method to quickly return the number of differences between two large lists. To compare your list elements using their primary key, let's index them by key using a dictionary: A_dict = {a[0]: a[1:] for a in A} B_dict = {b[0]: b[1:] for b in B} I'm new to python and I'm using python 2. I have 2 lists with elements like: list1=[2,54,31,6,42] list2=[4,98,43,3,2] I want a def that compares the numbers and returns a 3rd list with the biggest one. compare two lists (python) 1. Their contents don't play a role here. But it depends on the outcome required. keys() & set(lis)} Or you could use a simple dict comprehension with a in test against d: # python 2. But how to compare if they aren't? I need faster way, because I'm working with df with 98800 observations. lower() == string2. In this instance index 1 in list1 != index 1 in list 2 so I want to append index+1 and the incorrect student answer (in this case the letter c) to the empty list. regards, python; list; comparison; Share. Thanks in advance. 7 . The function implements to each element of the list and returns an iterator as a result. The Overflow Blog “You don’t want to I want to return two lists from a function in python. > i:1 > 'c' refers to the top level and the i:1 refers to index 1 of the list being compared): compare(ldA, ldB) . Community Bot. I'm trying to compare the first character of two different strings (and so on) to form a new string based on those results. Then, we can compare the two lists. I want to compare index 0 in list1 to index 0 in list2 and, if they are equal, move to compare index 1 in each list. The split-method of the string returns a list. The problem is that as soon as you find the first common element in the two lists, you return that single element only. Here, lists required_tiems and packed_items are converted into sets using the set() method without considering the order of the elements in the list. ANd i wish to compare the two xml files. list_1 = ['a', 'a', 'a', 'b'] list_2 = ['a', 'b', 'b', 'b', 'c'] so in the list above, only items in index 0 is the same while index 1 to 4 in both list are different To add to erlinska's answer, you can reduce the solution to a single line using a list comprehension and zip. Basic List Comparison. b = set(b) return [aa for aa in a if aa not in b] def set I have 2 Dataframes with same schema and different data. As you can see, a letter can be repeated multiple times at a different index position. In this tutorial, we will explore various methods to compare two lists in Python. For context, they each store indices into a different, 2D tensor, so if I could use them like numpy arrays I might do something like: You can also use a list comprehension and compare the rows to return the missing elements: dif_list = [x for x in list(df1['City']. If I have two lists (may be with different len): x = [1,2,3,4] f = [1,11,22,33,44,3,4] result = [11,22,33,44] im doing: for element in f: if element in x: f. I want to compare the corresponding values in the list (except the first item) and print out the ones which dont match. Just for the sake, i still did some tests. append(x) return result The problem is it's not working. Compare two lists in python where the elements are in different order. And how to read them in the main program. One way is to use a Boolean series to index the column df['one']. I would like to compare 5 lists regarding their length and return the longest list. If both lists are similar, it returns True. python compare difference between two lists. subdirs. comparing two different lists. Create Basic Excel Pivot The reason your approach fails is that python in operator check the index of a Series instead of the values, GroupBy. In this case, we want to return the length of the shorter list; In ether cases, the min() expression is what we want. 1 1 1 compare to lists and return the different indices and elements in python. A list in Python is very different from an array. I want to find all the changes between d1 and d2. I want to compare sublists of my list and return the unmatched variables input is lst = [['2','b'], ['!d','e'], ['s','f', 'd'], ['24','!b'], ['and','7']] desired I have two very large lists, one is 331991 elements long, lets call that one a, and the other is 99171 elements long, call it b. We’ll cover simple equality checks, membership testing, element-wise comparisons, and advanced I have two lists which are guaranteed to be the same length. Swap those lists and you get a different result. This approach simply uses the == operator to compare 2 lists element-wise and returns True if they have the same length and the same elements in the I have two lists of dicts, one is a modified subset of the other. txt' list2=[2,4,6,8,10] #this list in file 'b. The Boolean series is just given by your if statement (although it is necessary to use & instead of and): >>> df['que'] = df['one'][(df['one'] >= df['two']) & (df['one'] <= Is there any way / class / module in python to compare two json objects and print the changes/differences? I have tried with "json_tools" which is gives fairly good results, however diff failed in case if there are python lists' with elements in Learn easy tips and tricks to compare two lists and return differences in Excel. python; an use sequence unpacking to assign them to two different names when calling the function: def f(): return [1, 2, 3], ["a", "b", "c"] list1, list2 = f() In Python, it's common to need to compare two lists to find their differences, intersections, unions, and more. The comparison I need is to compare the first item in List 1 with the first item in List 2, the second item in List 1 with the second item in List 2, and so on, and returns a result if ALL of the list items follow the same comparison criteria. 6 ≤ x < 3. diff_files if differences: return True return any([has_differences(subdcmp) for subdcmp in dcmp. There are different ways to compare lists in Python. – For starters I've only been playing with python for about a 2 weeks now and im relatively new to its proccessess, I'm trying to create a script that compares two directories with subdirectories and prints out ANY changes. As for the speed, with Python 2, your solution is indeed about 15% faster than the zip() solution, on 10k elements; with Python 3, it is twice as slow, probably because zip() returns an iterator (no in-memory zipped list), in Python 3. Assuming sorting or de-duplication definitely make it easier to compute the difference, but if your comparison cannot afford those assumptions then you'll need a non-trivial implementation of a diff algorithm. The 2nd code snippet is significantly different in that it builds a pointless lists of None values returned by the print calls- this is unpythonic, If you want to compare two lists for differences, I think you want to use a set. Using Python 2, calling . The code I have works for smaller lists but not the larger lists I'm writing it for. != len(b): return False if type(a) == type(b) == list: return a == b a = tuple(a) b = tuple(b) return a == b Share. Commented Jun 24, 2022 at 9:42. My code is this: list1 = [1,0,1,0,1,1,0,0] list2 = [1,0,0,1,0,0,1,1] def listCompare(lst1, lst2): for i in Compare two lists different in two elements in the same position Compare items from two lists in Python. This can be done using simple comparison operators or built-in Code Implementation to Find The Difference Between Two Lists. Python: Compare two identical dictionaries by key, value Comparing values of two dictionaries. OrderedDict is also not hashable. This gives you a new column where the True entries have the same value as the same row as df['one'] and the False values are NaN. html html files directly as they are. How to add the missing element to second list by comparing two lists. join(missingOnStore))) The original code stops at the first I want to be able to output the position and change for the differences in the two lists. I have two dictionaries, and I need to find the difference between the two, which should give me both a key and a value. Only one list need be converted to a set: set(b). I was wondering how I would compare two 2-dim lists by their location. difference(a) for instance with set. So I have a python dictionary, call it d1, and a version of that dictionary at a later point in time, call it d2. Can anyone suggest a solution to this? Any help would be appreciated! Thanks, Adam How can I return a new list of Size(15) with boolean values if the item in list1 is in list2? In list2 there are some items multiple times, in list1 every item appears just once. # python 2. 3. Read the documentation. In this case, we want to return the length of either lists. The article consists of five examples explaning string list comparison. This is the code that I have tried, but I can't seem to print out the second location accurately. The strings should be displayed even if in one is used uppercase and in the other lowercase or a combination of it. In this example the 3rd list would The above examples trivialized the problem of calculating differences. apply(lambda row:process. lower() on each string or Unicode object string1. Using sets will return the lowercased values and will delete all I need to compare two CSV files and print out differences in a third CSV file. Make a df where the firse col ref is ref_list and the second col inp is each name in inp_list. Or even better, use the standard function zip to go through both sequences at once. How to compare two dictionaries with list values? 3. d1= {'as': 1, 'a': {'b': {'cs':10, 'qqq': {'qwe':1} }, 'd': {'csd':30} } } d2= {'as': 3, 'a': {'b': {'cs':30, 'qqq': 123 Order comparison for lists. Share. groupby('A')['C']. Lists in Python: Lists are the most versatile ordered list object type in Python. , it find symmetric difference). Viewed 47k times Compare two lists and get the indices where the values are different. @user2314520: another way to look at it is: it finds a union of both lists without including an intersection of the lists (i. I have searched and found some addons/packages like datadiff and dictdiff-master, but when I try to import them in Python 2. list1 = [[1,0], [2,1], [3,0]] #[[id, value]] list2 = [[1,1], [2,1], [3,1]] #[[id, value]] getDifference(list1, list2) #should return [1, 3] Because in the above example 1 and 3 are the only ids which value is different in list2 in compare to list1 Oh, sorry. nykwi fyda osqtpd vhvsyi tzk qfciv chus vbrm cbeq evina