Detect Missing Values

Detect missing values. NA values, such as None or numpy.NaN, get mapped to True values. Everything else is mapped to False values. Characters like empty strings or numpy.inf are not considered NA (unless pandas.options.mode.use_inf_as_na is set).

Detect Missing Values Again

This detection is identical to the previous one, ensuring consistency in value identification.

isna vs. isnull

In Python, isna and isnull are identical, with the same documentation and implementation. The reason for having two methods with different names is rooted in pandas' heritage from R, where NA and null are distinct concepts.

References

For further reading, refer to the relevant documentation and sources cited in the original context.