pandas needs pyarrow, which doesn't exist

[Ross Boylan]

python3-pandas needs certain packages which are not listed among its dependencies, even as suggests, and are not available in Ubuntu. I ran into this while using feather. Here's a debug session; earlier import pandas as pd we executed.
(Pdb) c
> /usr/local/fahydev/Kornak/bifs/examples/investigate09.py(59)<module>()
-> subsample = pd.read_feather(SUBFILE).astype({"id": int})
(Pdb) n
ImportError: Missing optional dependency 'pyarrow'. Use pip or conda to install pyarrow.

The removal of support for feather and the absence of a suitable package is noted in the changelog for 0.25.2+dfsg-1.

apache provides packaging and instructions upstream, but it would be really nice if this just worked.

Note that python3-arrow, an existing Ubuntu package, has absolutely nothing to do with the pyarrow library.

Desired Outcome:
pyarrow packaged like other python libraries.
The relevant package listed as a dependency of python3-pandas (I'd be fine with recommends though suggests would do).

In case the info I uploaded didn't get through, this is on Ubuntu 20.04 with python3-pandas 0.25.3+dfsg-7

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: python3-pandas 0.25.3+dfsg-7
ProcVersionSignature: Ubuntu 5.4.0-1039.41-azure 5.4.78
Uname: Linux 5.4.0-1039-azure x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
Date: Wed Feb 17 16:01:02 2021
InstallationDate: Installed on 2020-10-02 (138 days ago)
InstallationMedia: Ubuntu-Server 18.04.5 LTS "Bionic Beaver" - Release amd64 (20200810)
PackageArchitecture: all
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: pandas
UpgradeStatus: Upgraded to focal on 2020-10-02 (138 days ago)