How to split column element and replace by other column value in python dataframe?-CodePudding

I want to replace col1 element with col2. For example if col1 contains abc i want to replace it with a{colb}c.

import pandas as pd
d = {'col1': ['a b', 'a c'], 'col2': ['z 26', 'y 25']}
df = pd.DataFrame(data=d)
print(df)
    col1     col2
    a b      z 26
    a c      y 25

output required if df['col1']=='a b'

    col1    col2     col3
0   a b     z 26     a z
1   a c     y 25     a c

I tried

df['col3'] = np.where(df[df['col1']=='a b'],(df['col1'].replace(str(df['col1'].str.split(' ')[1])),(str(df['col2'].str.split(' ')[0]))), 0)

error: ---error: operands could not be broadcast together with shapes (1,3) (2,) ()

for x in df['col1']:
  x.replace(df['col1'].str.split(' ')[1],df['col2'].str.split(' ')[1])
#error --replace() argument 1 must be str, not list

suggest easy solution...

CodePudding user response：

I'm not entirely certain I've understood what you're trying to do here, but something this does what you ask for:

for i, row in df2.iterrows():
    if row["col1"] == "a b":
         row["col1"] = "a "   row["col2"].split(" ")[0]

To iterate a dataframe row-wise, you use iterrows, which returns a tuple of (index, row).

Note that the condition -- 'a b' ---is hard coded here, which seems to be what you want.

CodePudding user response：

While this is quite messy, I managed to do it in one line. I am honestly not sure if it does exactly what you want, but I can give you a hand modifying it if necessary.

df['col3'] = [f'{i[1].col1.split()[0]} {i[1].col2.split()[0]}' if i[1].col1 == 'a b' else i[1].col1 for i in df.iterrows()]

CodePudding user response：

I found a way like this: split both column and join them. However I was looking for replacement and Insert

df['col3'] = df['col1'].apply(lambda x:x.split(' ') [0])  ' '  df['col2'].apply(lambda x:x.split(' ') [0])