I have two lists
list1=['value1', 'value2', 'value3']
list2=['value1', 'value2', 'value3', 'value4', 'value5']
I want to delete the contents of list1 from list2
Result should be :
['value4', 'value5']
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2Do you want to remove those elements from the existing list, or create a new, filtered list?tobias_k– tobias_k2020-06-25 09:46:40 +00:00Commented Jun 25, 2020 at 9:46
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1stackoverflow.com/questions/3462143/…Shijith– Shijith2020-06-25 09:51:50 +00:00Commented Jun 25, 2020 at 9:51
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4 Answers
You can do it by converting the list1 to set and then by list comprehension create a new list with the items from list2 that not in list1
list1=['value1', 'value2', 'value3']
list2=['value1', 'value2', 'value3', 'value4', 'value5']
list1_set = set(list1)
result = [i for i in list2 if i not in list1_set]
print(result)
Output
['value4', 'value5']
The conversion of list1 to set is from better performances since checking if an item is in a set is faster than in a list.
Comments
list2 = [elem for elem in list2 if elem not in list1]
1 Comment
tobias_k
Technically, this does not remove from
list2 but overwrite the variable with a new list. You could e.g. use list[:] = ... to replace all elements in list2. Also, converting list1 to set might be faster.To print the values of items in list2 that are not in list1, you can use this code:
list1=['value1', 'value2', 'value3']
list2=['value1', 'value2', 'value3', 'value4', 'value5']
print([list2 for list2 in list2 if list2 not in list1])
1 Comment
juanpa.arrivillaga
Note, this works, but is inefficient.
list1=['value1', 'value2', 'value3']
list2=['value1', 'value2', 'value3', 'value4', 'value5']
set_list_1 = set(list1)
set_list_2 = set(list2)
print(list(set_list_2.difference(set_list_1)))
['value4', 'value5']
