如何在python中减去2个字符串或列表？

Question

I have very large strings in my codes. I would like to detect different characters between the strings. Here is an example what I mean:

 a='ababaab'
 b='abaaaaa'
 a=a-b
 print(a)

I expect kind of like these; 'bb' or '000b00b'

I know sounds weird but I really need this.

Answer 1

You could do:

a = 'ababaab'
b = 'abaaaaa'

a = ''.join(x if x != y else '0' for x, y in zip(a, b))
# '000b00b'
# OR
a = ''.join(x for x, y in zip(a, b) if x != y)
# 'bb'

Answer 2

Here is the example: It works wih list

listA = ["a","b"]
listB = ["b", "c"]
listC = [item for item in listB if item not in listA]
print listC

Output

# ['c']

Answer 3

You can create custom function as following: (assumption length of both strings are equal)

def str_substract(str1, str2):
    res = ""
    for _ in xrange(len(str1)):
        if str1[_] != str2[_]:
            res += str1[_]
        else:
            res += "0"
    return res

a='ababaab'
b='abaaaaa'

print str_substract(a, b)

output:

000b00b

Answer 4

result = ''

for temp in a:
    result += temp if temp not in b else '0'

Answer 5

Use zip :

res = ''
for i, j in zip(a, b):
     if i == j:
         res += '0'
     else:
         res += i

Using a list to store the result is probably more efficient.

Answer 6

if you want s1 - s2 :

   s1 = 'ababaab'
    s2 = 'abaaaaa'



   for i,j in zip(s1,s2):
        if (i != j):
            print i,

output : bb