Source code for draugr.pandas_utilities.multi_index_utilities

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

__author__ = "Christian Heider Nielsen"
__doc__ = r"""

           Created on 25-05-2021
           """

from typing import Any

import numpy
import pandas

__all__ = ["add_index_level"]


[docs]def add_index_level( old_index: pandas.Index, value: Any, name: str = None, loc: int = 0 ) -> pandas.MultiIndex: """ Expand a (multi)index by adding a level to it. :param old_index: The index to expand :param name: The name of the new index level :param value: Scalar or list-like, the values of the new index level :param loc: Where to insert the level in the index, 0 is at the front, negative values count back from the rear end :return: A new multi-index with the new level added """ def _handle_insert_loc(loc: int, n: int) -> int: """ Computes the insert index from the right if loc is negative for a given size of n. """ return n + loc + 1 if loc < 0 else loc loc = _handle_insert_loc(loc, len(old_index.names)) old_index_df = old_index.to_frame() old_index_df.insert(loc, name, value) new_index_names = list( old_index.names ) # sometimes new index level names are invented when converting to a df, new_index_names.insert(loc, name) # here the original names are reconstructed new_index = pandas.MultiIndex.from_frame(old_index_df, names=new_index_names) return new_index
if __name__ == "__main__": def stest_add_index_level() -> None: """ :rtype: None """ df = pandas.DataFrame(data=numpy.random.normal(size=(6, 3))) i1 = add_index_level(df.index, "foo") # it does not invent new index names where there are missing assert [None, None] == i1.names # the new level values are added assert numpy.all(i1.get_level_values(0) == "foo") assert numpy.all(i1.get_level_values(1) == df.index) # it does not invent new index names where there are missing i2 = add_index_level(i1, ["x", "y"] * 3, name="xy", loc=2) i3 = add_index_level(i2, ["a", "b", "c"] * 2, name="abc", loc=-1) assert [None, None, "xy", "abc"] == i3.names # the new level values are added assert numpy.all(i3.get_level_values(0) == "foo") assert numpy.all(i3.get_level_values(1) == df.index) assert numpy.all(i3.get_level_values(2) == ["x", "y"] * 3) assert numpy.all(i3.get_level_values(3) == ["a", "b", "c"] * 2) # df.index = i3 # print() # print(df) stest_add_index_level()