Search code examples
jsonmathjqtruncate

How to round, floor, ceil, truncate

How can I round, floor, ceil, and truncate a number in jq jq-1.5-1-a5b5cbe?

For example, with {"mass": 188.72}, I want {"mass": 188} with floor, {"mass": 189} with ceil and round.

Rounding examples:

5.52 --> 6
5.50 --> 5 or 6
-5.52 --> -6

Truncate examples:

5.52 --> 5
5.50 --> 5
-5.52 --> -5

I have come up with -5 as $n | if $n > 0 then [range($n+0.00000000000001)] else [range(-$n)] end | last for truncate, but it is needlessly complex (and likely contains bugs).

Solution

  • Some builds may lack those functions, but as far as I'm concerned floor is widely available; so, you can implement them using it.

    round/0

    def round: . + 0.5 | floor;

    ceil/0

    def ceil: if . | floor == . then . else . + 1.0 | floor end;

    trunc/0

    def trunc: if . < 0 then ceil else floor end;