将分数转换为浮点数? [英] Convert fraction to float?

问题描述

种类类似于此问题的类似，但相反

Kind of like this question, but in reverse.

给出像1，1/2或1 2/3这样的字符串，将其转换为浮点数的最佳方法是什么?我正在考虑根据情况使用正则表达式，但也许有人知道更好的方法或预先存在的解决方案.我希望可以只使用eval，但是我认为第3种情况可以防止这种情况.

Given a string like 1, 1/2, or 1 2/3, what's the best way to convert it into a float? I'm thinking about using regexes on a case-by-case basis, but perhaps someone knows of a better way, or a pre-existing solution. I was hoping I could just use eval, but I think the 3rd case prevents that.

推荐答案

我稍微调整了 James的回答. /p>

I tweaked James' answer a bit.

def convert_to_float(frac_str):
    try:
        return float(frac_str)
    except ValueError:
        num, denom = frac_str.split('/')
        try:
            leading, num = num.split(' ')
            whole = float(leading)
        except ValueError:
            whole = 0
        frac = float(num) / float(denom)
        return whole - frac if whole < 0 else whole + frac


print convert_to_float('3') # 3.0
print convert_to_float('3/2') # 1.5
print convert_to_float('1 1/2') # 1.5
print convert_to_float('-1 1/2') # -1.5

http://ideone.com/ItifKv

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