Create a new column based on NaN values in another column-CodePudding

I have a pandas data frame with column A:

A
5
1
NaN
12
13
NaN
NaN

how can I create a new column B based on A to give True if the value is known and False if the value is NaN with an output like this:

A	B
5	True
1	True
NaN	False
12	True
13	True
NaN	False
NaN	False

Thanks

CodePudding user response：

Use notna:

df['B'] = df['A'].notna()

output:

      A      B
0   5.0   True
1   1.0   True
2   NaN  False
3  12.0   True
4  13.0   True
5   NaN  False
6   NaN  False

CodePudding user response：

Use the .isna() (or .isnull()) method to determine if the value is Nan. It returns True for Nan and False for the rest, so we need to negate that. Negation is done with ~ operator.

df['B'] = ~df['A'].isna()