solidsnack / short-duration-presentation

Short Formats for Short Durations

Short Formats for Short Durations

present(seconds: f64)	formatted result
present(0.01)	010ms
present(1.0)	1.00s
present(10.0)	10.0s
present(100.0)	1m40s
present(1000.0)	0h17m
present(10000.0)	2h47m
present(100000.0)	1d04h
present(1000000.0)	01w5d
present(10000000.0)	16w4d
present(100000000.0)	3y09w
present(1000000000.0)	0032y
present(10000000000.0)	0317y

Formats & Ranges Covered

format	smallest unit multiple	range multiple	values covered
000ms			up to 00.9995000000s
0.00s	10×	10×	up to 09.9950000000s
00.0s	10×	10×	up to 99.950000000s (about 1½ minutes)
0m00s	10×	6×	up to 09m59.5s
0h00m	60×	60×	up to 09h59m30s
0d00h	60×	24×	up to 9d23h30m
00w0d	24×	70×	up to 99w6d12h (about 1 year, 9 months)
0y00w	7×	5.21775×	up to 9y51w4d02h54m36s
0000y	52.1775×	1000×	up to 9999y26w0d14h54m36s
10ky+			values outside representation range

As regular expressions:

format	matcher
000ms	([0-9][0-9][0-9])ms
0.00s	([0-9][.][0-9][0-9])s
00.0s	([0-9][0-9][.][0-9])s
0m00s	([0-9])m([0-9][0-9])s
0h00m	([0-9])h([0-9][0-9])m
0d00h	([0-9])d([0-9][0-9])h
00w0d	([0-9][0-9])w([0-9])d
0y00w	([0-9])y([0-9][0-9])w
0000y	([0-9][0-9][0-9][0-9])y
10ky+	10ky[+]

The Rounding Rules for Years

For units longer than a second, there is some ambiguity as to their actual duration. In UTC timekeeping, a "leap second" is occasionally introduced into the last minute (and thus last hour and day) of a year; and even if we set aside the leap second and adopt fixed minutes, hours and days (the "SI Day" of 86400 seconds), there is also the matter of leap years, of which there are 97 every 400 years.

The average Gregorian year is 365.2425 SI days, which provides a simple basis for our calculations that is quite accurate for many purposes, and certainly for giving a sense of time elapsed when many years have passed; but the year is nevertheless a complex case for rounding because it is a non-integer number of days and a non-integer number of weeks (52 weeks is 364 days).

We can ask two questions to come up with rounding rules for years:

1. When is a time between 1y51m and 2y00w closer to 2y00w ?
2. When is a time between 0019y and 0020y closer to 0020y ?

The answer to the first question helps us to set the upper limit for the format 0y00w, while the answer to second helps us to set the upper limit for the format 0000y, as well as helping us to round values:

1. From 1y51w0d to 2y00w0d we have 712152 seconds or 8d05h49m12s . The point where we get closer to 2y00w is 356076 seconds or 4d02h54m36s.
2. From 0019y00w0d to 0020y00w0d there are 31556952 seconds. Half this value is 15778476 seconds, or 26w0d14h54m36s.