替换逗号小数点的数据帧列，使其数字

Question

import pandas as pd  
df = pd.DataFrame([["one", 1.2, "", "4,3"], 
    ["two","1,7", "2,4", 0.55], 
    ["three","", 5.4, "3,9"]], 
    columns=['a','b','c','d']) 

我如何可以替换列中的逗号b键d至点，使这些列的数字？ 列（或任意数量的前导列的）应当保留不变（可以包含逗号为好）

Answer 1

import re  

for col in ['b', 'c', 'd']: 
    df[col] = pd.to_numeric(df[col].apply(lambda x: re.sub(',', '.', str(x)))) 

Answer 2

你可以试试这个：

df = df.set_index('a') 
df.apply(lambda x: x.str.replace(',','.')).combine_first(df).apply(lambda x:pd.to_numeric(x,errors='coerce')).reset_index() 

输出：

 a b c  d 
0 one 1.2 NaN 4.30 
1 two 1.7 2.4 0.55 
2 three NaN 5.4 3.90 

列A逗号测试

df = pd.DataFrame([["one", 1.2, "", "4,3"], 
    ["two","1,7", "2,4", 0.55], 
    ["three","", 5.4, "3,9"], 
    ["comma, here","2,1",1.2,""]], 
    columns=['a','b','c','d']) 

df = df.set_index('a') 
df2 = df.apply(lambda x: x.str.replace(',','.')).combine_first(df).apply(lambda x:pd.to_numeric(x,errors='coerce')).reset_index() 

print(df2) 

      a b c  d 
0   one 1.2 NaN 4.30 
1   two 1.7 2.4 0.55 
2  three NaN 5.4 3.90 
3 comma, here 2.1 1.2 NaN