pandas compare two dataframes and creating 0 columns-CodePudding

I have two dataframes as follows:

df1

Year    Column1   Column2   Column3
2022    1          2         3
2022    5          7         9


df2

Year    Column1    Column4    Column5
2022     1          2          4

What I want to achieve is that in df2, I want to detect the missing columns (in this case it would be Column2 and Column3 and fill 0) So my df2 would ultimately look like:

df2

Year     Column1   Column4   Column5   Column2   Column3
2022      1         2         4         0         0

How do I achieve this? I tried map but wasnt able to get it to work. Thanks!

CodePudding user response：

Use reindex and column union:

out = df2.reindex(df2.columns.union(df1.columns), axis=1, fill_value=0)

To update in place:

df2.update(df2.reindex(df2.columns.union(df1.columns), axis=1, fill_value=0))

CodePudding user response：

You can loop over the columns in df1, check if they are in df2 and, if they are not, add them in like this:

for col in df1.columns:
    if col not in df2.columns:
        df2[col] = 0