pandas.isnull

pandas.isnull(obj)

Detect missing values for an array-like object.

This function takes a scalar or array-like object and indicates whether values are missing (NaN in numeric arrays, None or NaN in object arrays, NaT in datetimelike).

Parameters:

objscalar or array-like

Object to check for null or missing values.

Returns:

bool or array-like of bool

For scalar input, returns a scalar boolean. For array input, returns an array of boolean indicating whether each corresponding element is missing.

See also

notna

Boolean inverse of pandas.isna.

Series.isna

Detect missing values in a Series.

DataFrame.isna

Detect missing values in a DataFrame.

Index.isna

Detect missing values in an Index.

Examples

Scalar arguments (including strings) result in a scalar boolean.

>>> pd.isna("dog")
False

>>> pd.isna(pd.NA)
True

>>> pd.isna(np.nan)
True

ndarrays result in an ndarray of booleans.

>>> array = np.array([[1, np.nan, 3], [4, 5, np.nan]])
>>> array
array([[ 1., nan,  3.],
       [ 4.,  5., nan]])
>>> pd.isna(array)
array([[False,  True, False],
       [False, False,  True]])

For indexes, an ndarray of booleans is returned.

>>> index = pd.DatetimeIndex(["2017-07-05", "2017-07-06", None, "2017-07-08"])
>>> index
DatetimeIndex(['2017-07-05', '2017-07-06', 'NaT', '2017-07-08'],
              dtype='datetime64[s]', freq=None)
>>> pd.isna(index)
array([False, False,  True, False])

For Series and DataFrame, the same type is returned, containing booleans.

>>> df = pd.DataFrame([["ant", "bee", "cat"], ["dog", None, "fly"]])
>>> df
     0     1    2
0  ant   bee  cat
1  dog  None  fly
>>> pd.isna(df)
       0      1      2
0  False  False  False
1  False   True  False

>>> pd.isna(df[1])
0    False
1     True
Name: 1, dtype: bool