CODEWITHSUNDEEP
pythonpandasdataframe
Danush Aaditya
Danush Aaditya

Reputation: 73

Replace NaN values in pandas dataframe with a computation from other columns

I have a DataFrame with column3 containing NaN values. I want to replace these NaN values with column2-column1. But column 2 is a string and I want to take the first four digits from the string and convert it to integer before subracting.

I tried this:

df.column3.fillna(int(df.column2[:4]) - df.column1)

And I get this following error:

TypeError: cannot convert the series to <class 'int'>

Upvotes: 1

Views: 80

Answers (2)

Mayank Porwal
Mayank Porwal

Reputation: 34056

Use:

df.column3.fillna(df.column2.str[:4].astype('int') - df.column1)

Upvotes: 1

jezrael
jezrael

Reputation: 862681

Use str[:4] for first 4 values of strings with convert to numeric by Series.astype:

df.column3 = df.column3.fillna(df.column2.str[:4].astype(int) - df.column1)

Or by to_numeric if first solution failed:

df.column3 = df.column3.fillna(pd.to_numeric(df.column2.str[:4], errors='coerce') - df.column1)

Upvotes: 2

Related Questions