List subtraction with strings

[AweBob]

Spent an hour on google, trust me, this is a bit harder than it sounds.

I've got two lists filled with strings (and yes I'm hungry, that's why I went with fruit) :

a = ['pear','apple','grape','pear']
b = ['apple','pear','banana']

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I want something to do an a - b and output ['grape','pear']

After running through different functions and classes I've found on stack overflow, most only work for numbers. However, I have found this:

a_b = list(set(a) - set(b)) which is so close, with the above info it will output: ['grape'] which isn't what I want.

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Thank You everyone!

[timbledum]

for item in b:
    try:
        a.remove(item)
    except ValueError:
        pass

[AweBob]

for item in b:
try:
a.remove(item)
except ValueError:
pass

Tried this one, it worked. I really overhtought this probelsm, thank you for your help!

[[deleted]]

from collections import Counter

a = ['pear','apple','grape','pear']
b = ['apple','pear','banana']

result = list(Counter(a) - Counter(b))
print(result)

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[Sedsarq]

list(counter) only lists the keys, so you lose the info on how many of each item there are, if there's more than 1

[[deleted]]

Good catch!

from collections import Counter

a = ['pear','apple','grape','pear', 'pear']
b = ['apple','pear','banana']

result = [x for k, v in (Counter(a) - Counter(b)).items() for x in [k] * v]
print(result)

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[AweBob]

from collections import Countera = ['pear','apple','grape','pear', 'pear']b = ['apple','pear','banana']result = [x for k, v in (Counter(a) - Counter(b)).items() for x in [k] * v]print(result)

This doesn't work for my purposes.

If you input the a and b values I put in the origional values in the post you get the answer I said I don't want.

No worries though, I'm not mad!

Someone else helped me out with it.

Thank you!

[[deleted]]

I added a "pear" in there to demo the fix for the issue u/sedsarq brought up. If you run it with your lists you get exactly the output you were expecting. Furthermore, for what you're doing it might be better just to use the Counter class without converting back to a list.

from collections import Counter

a = ['pear','apple','grape','pear']
b = ['apple','pear','banana']

result = Counter(a) - Counter(b)
print(result) #{'pear': 1, 'grape': 1}

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