pyspark.pandas.window.RollingGroupby.median

RollingGroupby.median()

Calculate the rolling median.

Added in version 4.3.0.

Returns:

Series or DataFrame

Returned object type is determined by the caller of the rolling calculation.

See also

pyspark.pandas.Series.rolling

Calling object with Series data.

pyspark.pandas.DataFrame.rolling

Calling object with DataFrames.

pyspark.pandas.Series.median

Equivalent method for Series.

pyspark.pandas.DataFrame.median

Equivalent method for DataFrame.

Notes

median in pandas-on-Spark uses distributed percentile approximation algorithm unlike pandas, the result might be different with pandas.

Examples

>>> s = ps.Series([2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5])
>>> s.groupby(s).rolling(3).median().sort_index()
2  0     NaN
   1     NaN
3  2     NaN
   3     NaN
   4     3.0
4  5     NaN
   6     NaN
   7     4.0
   8     4.0
5  9     NaN
   10    NaN
dtype: float64

For DataFrame, each rolling median is computed column-wise.

>>> df = ps.DataFrame({"A": s.to_numpy(), "B": s.to_numpy() ** 2})
>>> df.groupby(df.A).rolling(2).median().sort_index()
         B
A
2 0    NaN
  1    4.0
3 2    NaN
  3    9.0
  4    9.0
4 5    NaN
  6   16.0
  7   16.0
  8   16.0
5 9    NaN
  10  25.0