ruby-on-rails - rails : How to print a decimal as a percent?

Question

有没有办法将小数打印为百分比，所以只有句点后的两位数？

我的小数点总是在 1 和 0 之间，所以我想从第三个字符开始调用 number.round(2) 是可行的，但我找不到它的语法任何地方。

为了澄清，我希望将数字存储为完整的小数，但打印为百分比。

Answer 1

您可能想要使用 number_to_percentage 方法。来自documentation ，这里有一些如何使用它的例子:

number_to_percentage(100)                                        # => 100.000%
number_to_percentage("98")                                       # => 98.000%
number_to_percentage(100, precision: 0)                          # => 100%
number_to_percentage(1000, delimiter: '.', separator: ',')       # => 1.000,000%
number_to_percentage(302.24398923423, precision: 5)              # => 302.24399%
number_to_percentage(1000, locale: :fr)                          # => 1 000,000%
number_to_percentage("98a")                                      # => 98a%
number_to_percentage(100, format: "%n  %")                       # => 100  %

选项:

:locale - Sets the locale to be used for formatting (defaults to current locale).
:precision - Sets the precision of the number (defaults to 3).
:significant - If true, precision will be the # of significant_digits. If false, the # of fractional digits (defaults to false).
:separator - Sets the separator between the fractional and integer digits (defaults to “.”).
:delimiter - Sets the thousands delimiter (defaults to “”).
:strip_insignificant_zeros - If true removes insignificant zeros after the decimal separator (defaults to false).
:format - Specifies the format of the percentage string The number field is %n (defaults to “%n%”).

或者你可以像下面这样写一些 ruby​​:

 class Numeric
   def percent_of(n)
    self.to_f / n.to_f * 100.0
   end
 end

p (1).percent_of(10)    # => 10.0  (%)
p (200).percent_of(100) # => 200.0 (%)
p (0.5).percent_of(20)  # => 2.5   (%)