pandas-从另一个df元素的split元素更新数据框中的值

Question

Python newb learning Pandas, so this is likely not the correct way to approach this.

In dataframe df , have columns testID and proj .

testID is an int (eg '23'), and proj is an underscore_separated_name with 3 parts (eg bob_xp_sam ). I wish to modify all testID values to become, for eg., xp-23 (by capturing the "xp" from proj and concatinating it to each existing testID value.)

This is where I am at, but it doesn't fly:

df['testID'] = df['proj'].str.split('_')[1] +'-'+ df['testID']

I have tried variations, such as:

df['proj'].split('_')[1]
 > AttributeError: 'Series' object has no attribute 'split'

df['proj'].str.split('_')[1]
> TypeError: can only concatenate list (not "str") to list

Pretty sure my approach is wrong - a little direction would be appreciated.

Answer 1

You need another str accessor before [1] to access individual element in the list type column (returned by split ):

df['proj'].str.split('_').str[1]
#                         ^^^