python - 在数据框列的多个位置插入字符

Question

我有一个有很多行的表，我需要更改所有第一个“”空格为“h”，第二个空格为“m”并在最后添加字符“s”

import pandas as pd

d = {'RA' : ['11 50 10.4747', "11 50 10.2641","11 50 10.0534", "11 50 09.8428"],'DEC':["+26 01 09.559","+26 01 10.770", "+26 01 11.980","+26 01 13.191"]}
df=pd.DataFrame(d)
for i in range(len(df)):
    RA = df['RA'][i]
    RA = str.replace(RA, " ", "h", 1)
    RA = str.replace(RA, " ", "m", 1)
    RA += "s"
    df['RA'][i] = RA
    DEC = df['DEC'][i]
    DEC = str.replace(DEC, " ", "d", 1)
    DEC = str.replace(DEC, " ", "m", 1)
    DEC += "s"
    df['DEC'][i] = DEC

我已经制作了这段代码，但我的使用速度越来越慢。使用此代码，我将数据框从:

     DEC             RA
+26 01 09.559  11 50 10.4747 
+26 01 10.770  11 50 10.2641  
+26 01 11.980  11 50 10.0534 
+26 01 13.191  11 50 09.8428

为此:

         DEC              RA
0  +26d01m09.559s  11h50m10.4747s
1  +26d01m10.770s  11h50m10.2641s
2  +26d01m11.980s  11h50m10.0534s
3  +26d01m13.191s  11h50m09.8428s

有什么功能可以做到这一点吗？我尝试使用 df.replace，但它替换了表中的所有“”...

现在谢谢

Answer 1

定义一个函数来处理 split 和重组。您可以使用 str.split，然后分别进行一些 super 简单的字符串连接。

def split_combine(v, letters=list('dms')):
    v = v.str.split(expand=True)
    return (
       v[0] + letters[0] 
     + v[1] + letters[1] 
     + v[2] + letters[2]
    )

现在，使用适当的参数调用它。

df['DEC'] = split_combine(df.DEC, list('dms'))
df['RA'] = split_combine(df.RA, list('hms'))

df
              DEC              RA
0  +26d01m09.559s  11h50m10.4747s
1  +26d01m10.770s  11h50m10.2641s
2  +26d01m11.980s  11h50m10.0534s
3  +26d01m13.191s  11h50m09.8428s