[SOLVED] How to compare two columns and input the smaller one in a new column in pandas?

Issue

I am working on a DataFrame that looks like this. I’d like to choose the faster date of the two and put it into another column.

and my desired out put is

So far I’ve tried

for i in range(len(df)):
    if df.loc[i, "col1"] < df.loc[i, "col2"]:
        df.loc[i, "col3"] = df.loc[i, "col1"]
    else:
        df.loc[i, "col3"] = df.loc[i, "col2"]

Solution

You could use min on axis:

df['col3'] = df[['col1','col2']].min(axis=1)

Output:

         col1        col2        col3
0  2015-01-03  2015-01-04  2015-01-03
1  2022-02-22  2017-01-02  2017-01-02

Answered By – enke

Answer Checked By – Mildred Charles (BugsFixing Admin)