Python 从字符串中过滤字符
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Filtering Characters from a String
提问by SunshineTS
I need to make a function that takes two strings as imnput and returns a copy of str 1 with all characters from str2 removed.
我需要创建一个函数，该函数将两个字符串作为输入并返回 str 1 的副本，其中删除了 str2 中的所有字符。
First thing is to iterate over str1 with a for loop, then compare to str2, to accomplish subtraction I should create a 3rd string in which to store the output but I'm a little lost after that.
第一件事是用 for 循环遍历 str1，然后与 str2 进行比较，以完成减法我应该创建第三个字符串来存储输出，但在那之后我有点迷失了。
def filter_string(str1, str2):
str3 = str1
for character in str1:
if character in str2:
str3 = str1 - str2
return str3
This is what I've been playing with but I don't understand how I should proceed.
这是我一直在玩的，但我不明白我应该如何进行。
采纳答案by NPE
Just use str.translate():
只需使用str.translate()：
In [4]: 'abcdefabcd'.translate(None, 'acd')
Out[4]: 'befb'
From the documentation:
从文档：
string.translate(s, table[, deletechars])Delete all characters from
sthat are indeletechars(if present), and then translate the characters usingtable, which must be a 256-character string giving the translation for each character value, indexed by its ordinal. Iftableis None, then only the character deletion step is performed.
string.translate(s, table[, deletechars])删除所有字符从
s是在deletechars（如果存在的话），然后翻译使用的字符table，它必须是256个字符的字符串，给出了翻译的每个字符值，其序索引。如果table是 None，则只执行字符删除步骤。
If -- for educational purposes -- you'd like to code it up yourself, you could use something like:
如果 - 出于教育目的 - 您想自己编写代码，您可以使用以下内容：
''.join(c for c in str1 if c not in str2)
回答by lecodesportif
Use replace:
使用replace：
def filter_string(str1, str2):
for c in str2:
str1 = str1.replace(c, '')
return str1
Or a simple list comprehension:
或者一个简单的列表理解：
''.join(c for c in str1 if c not in str2)
