Pandas- Comparing two columns with different indexes and different length

Question

I want to compare these two columns. When I used isin(), it operates with index, so even though four values are in common, it only returns one True.

How may I tackle this?

Many thanks,

Answer 1

IIUC use:

df['new'] = df['id'].isin(df['authorid'])

If not working checj if same types, if numeric or strings are same in both columns:

print (df.dtypes)

Then try eg convert to strings:

df['new'] = df['id'].astype(str).isin(df['authorid'].astype(str))