How to swap column1 value with colum 2 value under a condition in Pandas-CodePudding

I'd like to swap column1 value with column2 value if column1.value >= 14 in pandas!

col1	col2
16	1
3	2
4	3

This should become:

col1	col2
1	16
3	2
4	3

Thanks!

CodePudding user response：

Use Series.mask and re-assign the two columns values:

m = df["col1"].ge(14)

out = df.assign(
                col1=df["col1"].mask(m, df["col2"]),
                col2=df["col2"].mask(m, df["col1"])
                )

Output:

   col1  col2
0     1    16
1     3     2
2     4     3

CodePudding user response：

Simple one liner solution,

df.loc[df['col1'] >= 14,['col1','col2']] = df.loc[df['col1'] >= 14,['col2','col1']].values