API: Index vs Series constructor alignment · Issue #49372 · pandas-dev/pandas (original) (raw)

Skip to content

Navigation Menu

• • GitHub Copilot Write better code with AI
  • GitHub Advanced Security Find and fix vulnerabilities
  • Actions Automate any workflow
  • Codespaces Instant dev environments
  • Issues Plan and track work
  • Code Review Manage code changes
  • Discussions Collaborate outside of code
  • Code Search Find more, search less
• Explore
  • Learning Pathways
  • Events & Webinars
  • Ebooks & Whitepapers
  • Customer Stories
  • Partners
  • Executive Insights
• • GitHub Sponsors Fund open source developers
  • The ReadME Project GitHub community articles
• • Enterprise platform AI-powered developer platform
• Pricing

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Sign up

Appearance settings

Description

There has been long-running interest in aligning the behaviors of various constructors: e.g. #29973, #27460, #17246. But I don't see an issue that is specifically "Let's make Index behave like Series". So here goes.

Series goes through sanitize_array which calls a bunch of functions in core.dtypes.cast. Index uses casting/inference functions in indexes.base, as well as Index._ensure_array.

The remaining behavior differences AFAICT are:

• Series(non_round_floats, dtype=inty) silently ignores dtype while Index raises (closed by API: Series(floaty, dtype=inty) #49609)
• Series silently returns object instead of raising with Series(np.array(["aaa"], dtype=object), dtype="datetime64[ns]") (would be closed by API: stop silently ignoring parsing failures with dtype=dt64 #49358)
• API: pd.Series([py_date, py_datetime]) vs pd.Index([py_date, py_datetime]) #49341 different dtype inference with pydate objects
• API: Series([pd.NaT, None]) vs Index([pd.NaT, None]) #49340 different dtype inference with NaT-and-other-NAs
• API: Series(mixed_datetime_and_ints, dtype="M8[ns]") vs DatetimeIndex(same) mismatch #49037 different inference with mixed datetime-and-ints (would be closed by API: allow mixed-datetimes-and-ints in to_datetime, DatetimeIndex #49348)
• RangeIndex and MultiIndex cases that I'm ignoring
• Probably subtle differences in overflow-handling in FooIndex._ensure_array
• Deprecated (TODO: GH ref) Index inference of numeric dtype with ndarray[object-of-all-numbers]

(recently enforced deprecations including #49319, #49242, #48379 cut down on this a ton)

The first entry here (handling of non-round floats with inty dtype) would be the most invasive to align. The current Series behavior was in place before I got involved, so I'm not aware of the reasoning behind it. I'd be on board with deprecating it and changing it in 3.0.

Thoughts? cc @jorisvandenbossche @mroeschke @jreback @TomAugspurger @phofl