number format

[Li Chen]

Hi all,

I have a number, for example, 1.123456789. What is the Ruby way to
change it into whatever number of floating points such as 1.12,
1.123,1.1234568 or 1.12345679.

Thanks,

Li

 

[Daniel Finnie]

You can use the number.round method, but this doesn't take a number of
decimal places.

To round 1.234 to 1.23 use this code:
x = 1.234
x = x * 100 # -> 123.4
x = x.round -> 123
x = x / 100.0 => 1.23

At least, that's the best method I can find from the Ruby docs...

Dan

 

[George Ogata]

Hi all,

I have a number, for example, 1.123456789. What is the Ruby way to
change it into whatever number of floating points such as 1.12,
1.123,1.1234568 or 1.12345679.

Thanks,

Li

It might be better to leave the precision alone until you print it, in
which case, you can print it with #sprintf or String#% or similar:

irb(main):001:0> '%.2f' % 1.23456789
=> "1.23"
irb(main):002:0> '%.5f' % 1.23456789
=> "1.23457"

 

[chen li]

It might be better to leave the precision alone
until you print it, in
which case, you can print it with #sprintf or
String#% or similar:

irb(main):001:0> '%.2f' % 1.23456789
=> "1.23"
irb(main):002:0> '%.5f' % 1.23456789
=> "1.23457"

I think I prefer the suggestion.

Li





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[Jeremy Hinegardner]

Hi all,

I have a number, for example, 1.123456789. What is the Ruby way to
change it into whatever number of floating points such as 1.12,
1.123,1.1234568 or 1.12345679.

You could use facets:

% sudo gem install facets
% irb

irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> require 'facet/float/round_at'
=> true
irb(main):003:0> require 'facet/float/round_to'
=> true
irb(main):004:0> x = 1.123456789
=> 1.123456789
irb(main):005:0> x.round_at(3)
=> 1.123
irb(main):006:0> x.round_at(7)
=> 1.1234568
irb(main):007:0> x.round_at(100)
=> 1.123456789
irb(main):008:0> x.round_to(0.001)
=> 1.123
irb(main):009:0> x.round_to(0.000001)
=> 1.123457

enjoy,

-jeremy