如何在float中将浮点数舍入到指定的有效数字位数？ [英] How do I round a float to a specified number of significant digits in Ruby?

问题描述

如果有相当于 R's signif

It would be nice to have an equivalent of R's signif function in Ruby.

例如：

For example:

>> (11.11).signif(1)
10
>> (22.22).signif(2)
22
>> (3.333).signif(2)
3.3
>> (4.4).signif(3)
4.4 # It's usually 4.40 but that's OK. R does not print the trailing 0's
    # because it returns the float data type. For Ruby we want the same.
>> (5.55).signif(2)
5.6

推荐答案

有可能是更好的办法，但这似乎工作正常：

There is probably better way, but this seems to work fine:

class Float
  def signif(signs)
    Float("%.#{signs}g" % self)
  end
end

(1.123).signif(2)                    # => 1.1
(11.23).signif(2)                    # => 11.0
(11.23).signif(1)                    # => 10.0

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