根据另一列中的 NaN 值创建新列

Question

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

Answer 1

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

Answer 2

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()