How to modify full text of some columns in pandas

Question

I got a fairly big dataframe from a csv in pandas.

The problem is that on some columns I get strings of text which I would like to isolate the last character to turn it into integers.

I found a solution, but I am fairly sure it's not the most efficient. It goes like this:

import pandas as pd

df = pd.read_csv("filename")

cols = list(df.loc[:, 'col_a':'column_s'])
df_filtered = df[cols].dropna()

df_filtered['col_o'] = df_filtered['col_o'].str[-1:]
df_filtered['col_p'] = df_filtered['col_p'].str[-1:]
df_filtered['col_q'] = df_filtered['col_q'].str[-1:]
df_filtered['col_r'] = df_filtered['col_r'].str[-1:]
df_filtered['col_s'] = df_filtered['col_s'].str[-1:]

In terms of writing, this is not really efficient. So I've tried something like this:

colstofilter = list(df_filtered.loc[:, 'col_o':'col_s'])

for col in df_filtered[colstofilter]:
    print(df_filtered[col].str[-1:].head())

Printing it gives exactly what I want, but when I try to turn it into a function or a lamba or apply it to the dataframe, I get an error that it's not supported

Answer 1

Try this:

df_filtered.loc[:, 'col_o':'col_s'] = \
    df_filtered.loc[:, 'col_o':'col_s'].apply(lambda x: x.str[-1])