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Merged
olbrich merged 3 commits into from
Sep 1, 2024
Merged

best_prefix produces invalid results #347

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34dd214
best_prefix produces invalid results
olbrich Mar 16, 2024
637dcc6
Merge branch 'master' into issue170-best_prefix-produces-invalid-results
olbrich Sep 1, 2024
2090d55
best_prefix produces invalid results
olbrich Sep 1, 2024
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12 changes: 11 additions & 1 deletion lib/ruby_units/unit.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -1499,12 +1499,22 @@ def coerce(other)
[self.class.new(other), self]
end

# returns a new unit that has been scaled to be more in line with typical usage.
# Returns a new unit that has been scaled to be more in line with typical usage. This is highly opinionated and not
# based on any standard. It is intended to be used to make the units more human readable.
#
# Some key points:
# * Units containing 'kg' will be returned as is. The prefix in 'kg' makes this an odd case.
# * It will use `centi` instead of `milli` when the scalar is between 0.01 and 0.001
#
# @return [Unit]
def best_prefix
return to_base if scalar.zero?
return self if units.include?('kg')

best_prefix = if kind == :information
self.class.prefix_values.key(2**((::Math.log(base_scalar, 2) / 10.0).floor * 10))
elsif ((1/100r)..(1/10r)).cover?(base_scalar)
self.class.prefix_values.key(1/100r)
else
self.class.prefix_values.key(10**((::Math.log10(base_scalar) / 3.0).floor * 3))
end
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15 changes: 11 additions & 4 deletions spec/ruby_units/unit_spec.rb
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Expand Up @@ -2262,10 +2262,17 @@
specify { expect(RubyUnits::Unit.new('23 m').div(RubyUnits::Unit.new('2 m'))).to eq(11) }
end

context '#best_prefix' do
specify { expect(RubyUnits::Unit.new('1024 KiB').best_prefix).to eq(RubyUnits::Unit.new('1 MiB')) }
specify { expect(RubyUnits::Unit.new('1000 m').best_prefix).to eq(RubyUnits::Unit.new('1 km')) }
specify { expect { RubyUnits::Unit.new('0 m').best_prefix }.to_not raise_error }
describe '#best_prefix' do
it { expect(RubyUnits::Unit.new('1024 KiB').best_prefix).to have_attributes(scalar: 1, units: 'MiB') }
it { expect(RubyUnits::Unit.new('1000 m').best_prefix).to have_attributes(scalar: 1, units: 'km') }
it { expect(RubyUnits::Unit.new('1/1000 m').best_prefix).to have_attributes(scalar: 1.0, units: 'mm') }
it { expect(RubyUnits::Unit.new('1/100000 m').best_prefix).to have_attributes(scalar: 10, units: 'um') }
it { expect(RubyUnits::Unit.new('0 m').best_prefix).to have_attributes(scalar: 0, units: 'm') }
it { expect(RubyUnits::Unit.new('1000 kg').best_prefix).to have_attributes(scalar: 1000, units: 'kg') }
it { expect(RubyUnits::Unit.new('1_000_000 kg').best_prefix).to have_attributes(scalar: 1_000_000, units: 'kg') }
it { expect(RubyUnits::Unit.new('1/100 m').best_prefix).to have_attributes(scalar: 1, units: 'cm') }
it { expect(RubyUnits::Unit.new('1/10 m').best_prefix).to have_attributes(scalar: 10, units: 'cm') }
it { expect(RubyUnits::Unit.new('0.234 s').best_prefix).to have_attributes(scalar: 234, units: 'ms') }
end

context 'Time helper functions' do
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