This library converts a Float to a String with ultimate
control how many digits after the decimal point are shown and how the remaining
digits are rounded. It rounds, floors and ceils the "common" way (ie. half
up) or the "commercial"
way (ie. half away from
zero).
Example:
x = 3.141592653589793
round 2 x -- "3.14"
round 4 x -- "3.1416"
ceiling 2 x -- "3.15"
floor 4 x -- "3.1415"The given number of digits after decimal point can also be negative.
x = 213.14
round -2 x -- "200"
round -1 x -- "210"
ceiling -2 x -- "300"
floor -3 x -- "0"Commercial rounding means that negative and positive numbers are treated symmetrically. It affects numbers whose last digit equals 5. For example:
x = -0.5
round 0 x -- "0"
roundCom 0 x -- "-1"
floor 0 x -- "-1"
floorCom 0 x -- "0"
ceiling 0 x -- "0"
ceilingCom 0 x -- "-1"Have a look at the tests for more examples!
Why couldn't you just do x * 1000 |> round |> toFloat |> (flip (/)) 1000 in
order to round to 3 digits after comma? Due to floating point
arithmetic it might happen that it results into someting like
3.1416000000001,
although we just wanted 3.1416.
Under the hood this library converts the Float into a String and rounds it
char-wise. Hence it's safe from floating point arithmetic weirdness.
From the root of your Elm project run
elm install myrho/elm-round
Import it in your Elm modules:
import Round | Version | Notes |
|---|---|
| 1.0.4 | Upgrade to Elm 0.19 |
| 1.0.3 | Fix issues with number in scientific notation, complete rewrite. |
| 1.0.2 | Given number of digits after decimal point can be negative. |
| 1.0.1 | Upgrade to Elm 0.18 |
| 1.0.0 | First official release, streamlined API and tests, docs added |