def proportion_of_features_with_na(X: numpy.array,
y: numpy.array = None) -> float:
'''
Proportion of features with missing values.
Parameters
----------
X : numpy.array
2d-array with features columns.
y : numpy.array
Array of response values.
Return
------
float:
Number of features with missing values over total number of features.
'''
# check if is dataframe
X = (X if isinstance(X, pandas.DataFrame) else pandas.DataFrame(X))
has_na = X.isnull().any()
return has_na.sum() / X.shape[1]
