如何将分数转换为在 ruby​​ 中浮动 [英] how to convert a fraction to float in ruby

问题描述

我有一个字符串 "1/16" 我想将它转换为浮点数并乘以 45.但是，我没有得到想要的结果.

I have a string "1/16" I want to convert it to float and multiply it by 45. However, I dont get the desired results.

我正在脚本/控制台

>> "1/16".to_f
=> 1.0
>> "1/16".to_f*45
=> 45.0

我怎样才能得到 2.81

大图:我有一个这样的下拉菜单:

Bigger picture: I have a drop down like this:

<%=select_tag :volume, options_for_select(["", "1 g", "1/16 oz", "1/8 oz","1/4 oz",
"1/2 oz", "1 oz", "1/8 lb", "1/4 lb", "Single", "Multi 5" ], "N/A") %>

每当用户选择 oz 值时，我想将其乘以 45

whenever user selects oz value then i want to multiply it to 45

所以我这样做:

first, *rest = params[:volume].to_s.split(/ /)
if rest.first=="oz"
    @indprodprice = @prods.orig_price.to_i*first.to_f*28.3495
else 
    @indprodprice = @prods.orig_price.to_i*first.to_f*453.59237
end

推荐答案

看起来您将不得不自己解析分数.这适用于分数和整数，但不适用于混合数(即:1½ 不起作用.)

Looks like you're going to have to parse the fraction yourself. This will work on fractions and whole numbers, but not mixed numbers (ie: 1½ will not work.)

class String
  def to_frac
    numerator, denominator = split('/').map(&:to_f)
    denominator ||= 1
    numerator/denominator
  end
end

"1/16".to_frac * 45

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