Sort by 12-hour time?

Question

quick (and probably stupid) question this morning:

I have data being fed to my script that looks like this:

03:00P - Doctor appointment.
07:00P - Scheduled entry.
10:30A - Another entry.
11:00A - Daytime medication is due.
11:00P - Nighttime medication is due.
11:30P - Staff meeting.

Now I can't change the source of the data, and the output needs to look the same, but I need to sort it properly. Any ideas on fixing this?

Thanks!

You manage to avoid the interesting times: `12:05A - Just past midnight and long before 11:00A` and `12:05P - Just past midday and long before 11:00P`. The accepted answer does not handle those times correctly. — Jonathan Leffler, Aug 02 '13 at 16:19
You might find the information in [Convert 12-hour date/time to 24-hour date/time](http://stackoverflow.com/questions/440061/convert-12-hour-date-time-to-24-hour-date-time/440110#440110) useful in dealing with the issue. I think you're likely to find that preprocessing with Perl or Awk or Python to add a column containing the AM/PM time converted into 24-hour notation, then sorting on the 24-hour column, and then (if necessary) removing it is likely to be 'best', unless there's a built-in option to `sort` to handle AM/PM time sorting. — Jonathan Leffler, Aug 02 '13 at 16:40

score 1 · Accepted Answer · answered Aug 02 '13 at 14:53

1

Tell sort to first sort on the sixth character, then on the first to fifth:

sort -k1.6,1.6 -k1.1,1.5

answered Aug 02 '13 at 14:53

choroba

231,213
25
204
289

score 0 · Answer 2 · answered Aug 02 '13 at 14:53

If you take the A or P from the time and place it it front of the time, it sorts correctly just using the normal sort command. So maybe something like this:

awk '{print substr($1,6), $0}' < input  | sort | cut -d' ' -f2-

The awk command generates output like this:

P 03:00P - Doctor appointment.
P 07:00P - Scheduled entry.
A 10:30A - Another entry.
A 11:00A - Daytime medication is due.
P 11:00P - Nighttime medication is due.
P 11:30P - Staff meeting.

Which we then sort, and then strip the prefix.

Eh, I like @choroba's solution better. – larsks Aug 02 '13 at 14:53 — larsks, Aug 02 '13 at 14:53

score 0 · Answer 3 · edited May 23 '17 at 12:11

Here is a solution based on a simple Perl script derived from the answer to Convert 12-hour date/time to 24-hour date/time.

Source `s12.pl`

#!/usr/bin/env perl
use strict;
use warnings;

sub time_12h_to_24h
{
    my($t12) = @_;
    my($hh,$mm,$ampm) = $t12 =~ m/^(\d\d?):(\d\d?)\s*([AP]M?)/i;
    $hh = ($hh % 12) + (($ampm =~ m/AM?/i) ? 0 : 12);
    return sprintf("%.2d:%.2d", $hh, $mm);
}

while (<>)
{
    my($time_12h, $entry) = split / - /;
    my $time_24h = time_12h_to_24h($time_12h);
    print "$time_24h $time_12h - $entry";
}

Note that the code accepts both { AM, PM } and { A, P } and is neutral between upper-case and lower-case for the AM/PM indicator, and ignores spaces between the time and AM/PM indicator.

Input data

This data sets contains rows for 12:05A and 12:05P as well as the data from the question.

03:00P - Doctor appointment.
07:00P - Scheduled entry.
10:30A - Another entry.
11:00A - Daytime medication is due.
11:00P - Nighttime medication is due.
11:30P - Staff meeting.
12:05A - Just past midnight and long before 11:00A.
12:05P - Just past midday and long before 11:00P.

Double-filtered output

$ perl s12.pl data | sort | sed 's/^..:.. //'
12:05A - Just past midnight and long before 11:00A.
10:30A - Another entry.
11:00A - Daytime medication is due.
12:05P - Just past midday and long before 11:00P.
03:00P - Doctor appointment.
07:00P - Scheduled entry.
11:00P - Nighttime medication is due.
11:30P - Staff meeting.
$

Unfiltered output

$ perl s12.pl data | sort
00:05 12:05A - Just past midnight and long before 11:00A.
10:30 10:30A - Another entry.
11:00 11:00A - Daytime medication is due.
12:05 12:05P - Just past midday and long before 11:00P.
15:00 03:00P - Doctor appointment.
19:00 07:00P - Scheduled entry.
23:00 11:00P - Nighttime medication is due.
23:30 11:30P - Staff meeting.
$

Note that by placing the key column (24 hour time column) first in the output, the sort command is simplified (and, in general, it speeds up the sort too).

Sort by 12-hour time?

3 Answers3

Source s12.pl

Input data

Double-filtered output

Unfiltered output

Source `s12.pl`