Fix bug: if three columns, ensure last is "z"

Issue:
https://github.com/genenetwork/gn-gemtext-threads/blob/main/topics/gn1-migration-to-gn2/partial-correlations.gmi

* Fix a bug, caught when the function is called in a recursive form, with the
  "z*" columns reducing for each cycle through the recursive form.

  As it was, the last cycle through the recursive form would end up with a
  DataFrame with the columns "x", "y", and "z0" rather than the columns "x",
  "y", "z".

  This commit handles that edge case to ensure that the column name is changed
  from "z0" to simply "z".

0 files changed, 0 insertions, 0 deletions