替换多个相似的字符串 [英] Replacing multiple similar strings

问题描述

我有以下表达:

a = 'x11 + x111 + x1111 + x1'

我想替换以下内容:

from_ = ['1', '11', '111', '1111']to = ['2', '22', '333', '3333']

因此得到以下结果:

anew = 'x22 + x333 + x3333 + x2'

如何使用 Python 执行此操作?

这是一个类似的问题:Python 替换多个字符串.但是，在我的情况下，如果我在问题中使用建议的 anwsers，则替换的值会被自己覆盖.因此，在提到的链接中，结果是 'x22 + x222 + x2222 + x2'

解决方案

re.sub 来自 re 库(正则表达式)可以在您需要进行多值替换时使用.

re.sub 接受函数的附加参数，您可以在该函数中进行必要的更改.来自文档

<块引用>

re.sub(pattern, repl, string, count=0, flags=0)

如果 repl 是一个函数，它会为每一个非重叠的模式的出现.该函数接受一个单个匹配对象参数，并返回替换字符串.

_{(强调我的)}

这里的正则表达式很简单，即 \d+ 这意味着您正在匹配所有数字组.

您可以使用以下代码片段来获得所需的输出

导入重新a = 'x11 + x111 + x1111 + x1'定义替代(matched_obj):from_ = ['1', '11', '111', '1111']to = ['2', '22', '333', '3333']部分=matched_obj.group(0)如果参与 from_:返回到[from_.index(part)]退货部分anew = re.sub(r'\d+',substitute,a)

执行程序后，anew 的值将是 x22 + x333 + x3333 + x2 这是预期的答案.`

I have the folowing expression:

a = 'x11 + x111 + x1111 + x1'

and I would like to replace the following:

from_ = ['1', '11', '111', '1111']
to = ['2', '22', '333', '3333']

and therefore obtain the following result:

anew = 'x22 + x333 + x3333 + x2'

How can I do this using Python?

This is a similar question to: Python replace multiple strings. However in my case the replaced values are being overwiten by themselves if I use the suggested anwsers in the question. Hence, in the metioned link the result is 'x22 + x222 + x2222 + x2'

解决方案

re.sub from the re library (regex) can be used whenever you need to do multi-value replacements.

re.sub takes in the additional argument of a function, in that function you can make the necessary change. From the documentation

re.sub(pattern, repl, string, count=0, flags=0)

If repl is a function, it is called for every non-overlapping occurrence of pattern. The function takes a single match object argument, and returns the replacement string.

_{(emphasis mine)}

The regex here is simple, i.e, \d+ which implies that you are matching all the groups of digits.

You can utilize the following code snippet to get your desired output

import re

a = 'x11 + x111 + x1111 + x1'

def substitute(matched_obj):
    from_ = ['1', '11', '111', '1111']
    to = ['2', '22', '333', '3333']
    part = matched_obj.group(0)
    if part in from_:
        return to[from_.index(part)]
    return part

anew = re.sub(r'\d+',substitute,a)

After executing the program the value of anew will be x22 + x333 + x3333 + x2 which is the expected answer. `

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