Ruby's Float#round method gets the job done, but doesn't offer much
configurability. If you'd like to finely control how a rounded number will
display, ActiveSupport::NumberHelper offers
number_to_rounded.
When a precision is specified, it will apply to the fraction digits:
> ActiveSupport::NumberHelper.number_to_rounded(1.0, precision: 2)
=> "1.00"Unless you include significant: true in which case precision will refer to
the number of signficant digits:
> ActiveSupport::NumberHelper.number_to_rounded(1.0, precision: 2, significant: true)
=> "1.0"Because this is for display purposes, the return value is a string. You can further specify that insignificant zeros are stripped from the result:
> ActiveSupport::NumberHelper.number_to_rounded(1.0, precision: 2, significant: true, strip_insignificant_zeros: true)
=> "1"And for completeness, here is an example of a number being rounded up:
> ActiveSupport::NumberHelper.number_to_rounded(1.29, precision: 2, significant: true)
=> "1.3"