Backward compatibility of -distinct- command

[Hemanshu Kumar]

This is to flag a small backward compatibility issue with the super-useful -distinct- command by Nick Cox.

When doing

distinct varname

where varname has all missing values, the current version (1.4.1, created on 10 October 2020) of the distinct command displays

note: no distinct values satisfy specification

It produces no error, and does not define the scalars r(ndistinct) and r(N).

On the other hand, in a previous version of the command (1.2.1, from 1 March 2012), these were defined, and r(ndistinct) was simply set to zero.

This inconsistency broke my code recently. Fixing it was easy, but I wanted to flag the problem. My personal preference is for the old behaviour, but perhaps Nick had good reasons to change it?

[William Lisowski]

Odd, I just did

ssc install distinct

which installed 1.2.1 rather than 1.4.1. Can you tell us where your more recent version came from? Alternatively, uninstall it and reinstall from SSC and apparently you'll get what you want.

Added in edit: I see now that the later version is posted from the Stata Journal as dm0042_3. So

ado uninstall dm0042_3
ssc install distinct

should do the job until Nick updates the SSC version. :-)

[Nick Cox]

distinct is written by Gary M. Longton. and myself. Thanks for the comments.

I thjnk I agree that r(N) and r(ndistinct) should be returned as 0 in this circumstance.

[Hemanshu Kumar]

@Nick, just wanted to remind you to fix this in version 1.4.1 of -distinct-, please? The behaviour is inconsistent with the ssc version, which is 1.2.1.

[Nick Cox]

Thanks for the reminder.