带有lambda的Python pandas 应用困难 [英] Python pandas with lambda apply difficulty

问题描述

我正在运行以下功能，但是以某种方式努力将长度条件考虑在内(if部分).如果仅该函数，它将仅运行第一部分:

I am running the following function but somehow struggling to have it take the length condition into account (the if part). It simply runs the first part if the function only:

stringDataFrame.apply(lambda x: x.str.replace(r'[^0-9]', '') if (len(x) >= 7) else x)

由于某种原因，它只能以某种方式运行x.str.replace(r'[^0-9]', '')部分，在这里我被卡住了是我做错了什么.

it somehow only runs the x.str.replace(r'[^0-9]', '') part for some reason, what am I doing wrong here i have been stuck.

推荐答案

您可以使用

You can use applymap when you need to work on each value separately, because apply works with all column (Series).

然后代替使用 str.replace ，使用 re.sub 对于正则表达式更有效:

Then instead of using str.replace, use re.sub which works nicer for regexs:

print (stringDataFrame.applymap(lambda x: re.sub(r'[^0-9]', '', x) if (len(x) >= 7) else x))

示例:

import pandas as pd
import re

stringDataFrame = pd.DataFrame({'A':['gdgdg454dgd','147ooo2', '123ss45678'],
                                'B':['gdgdg454dgd','x142', '12345678a'],
                                'C':['gdgdg454dgd','xx142', '12567dd8']})

print (stringDataFrame)
             A            B            C
0  gdgdg454dgd  gdgdg454dgd  gdgdg454dgd
1      147ooo2         x142        xx142
2   123ss45678    12345678a     12567dd8

print (stringDataFrame.applymap(lambda x: re.sub(r'[^0-9]', '', x) if (len(x) >= 7) else x))
          A         B       C
0       454       454     454
1      1472      x142   xx142
2  12345678  12345678  125678

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