从 python function 中的列表中删除字符

Question

I am trying to learn functions in python, I come across a dead end for below problem where I have to write a function to take a list of strings as input, remove special characters and return a list with clean strings.

Code looks as below:

def cleanChar(a):
   a=[]
   b=[',','?','#','@','$','%','^','&','*','/']
   out_list=[]

   for x in a:
       for y in b:
           if y in x:
               x=x.replace(y,'')
               out_list.append
   return out_list


testq = ['#mahesh','%Po*hsi$','Iy&gdj']

test3=cleanChar(testq)
print(test3)

I get the out put as an empty list. What am I doing wrong here or what should have been my approach? Thanks in advance for the help.

Answer 1

I am seeing three issues with your code.

1. No need to re-initialize the function parameter a with []
2. out_list.append should be replaced with out_list.append(x)
3. out_list.append(x) must be in same indentation level as with for y in b . This is because we only want to append to the output list once all the characters are replaced.

So your final function looks like this.

>>> def cleanChar(a):
...     b = [",", "?", "#", "@", "$", "%", "^", "&", "*", "/"]
...     out_list = []
...     for x in a:
...         for y in b:
...             if y in x:
...                 x = x.replace(y, "")
...         out_list.append(x)
...     return out_list
...
>>> testq = ["#mahesh", "%Po*hsi$", "Iy&gdj"]
>>> test3 = cleanChar(testq)
>>> print(test3)
['mahesh', 'Pohsi', 'Iygdj']

Answer 2

import re
clean_testq = [re.sub('[^a-zA-Z]',"",each) for each in testq]
clean_testq

['mahesh', 'Pohsi', 'Iygdj']

Answer 3

You can run a simple list comprehension to check if an element in your input is not in b , then use join() to return a string of the result.

def cleanChar(a):
    b=[',','?','#','@','$','%','^','&','*','/']
    return ''.join([element for element in a if element not in b])

testq = ['#mahesh','%Po*hsi$','Iy&gdj']

for i in testq:
    print(cleanChar(i))

Outputs

mahesh
Pohsi
Iygdj