四舍五入的浮点数列表？

Question

我想将列表中的浮点数四舍五入到 python 中的下限，我试过 math.floor([i])，错误是：a float is required 我也试过 math.trunc([i]) ，我收到此错误：AttributeEror_trunc。我找不到任何合适的代码来解决这个问题。如有任何帮助，我们将不胜感激！

这是我目前的代码：

with open ("G:\Speed\december.sorted.movement.Sample.txt", 'r') as f:
    firs_line = f.readline()
    split=firs_line.split ("\t")

    Speed = [r.split()[5] for r in f]
    Speedf=[]
    for item in Speed:
        Speedf.append(float(item))

    denominator= 8677.8   
    i = [x/denominator for x in Speedf]

    import math
    v= math.floor([i])
    #print v [:5]

Answer 1

math.floor 需要一个浮点值。但是您似乎正在传递一个列表列表。

您可以使用列表理解：

v = [math.floor(float(x)) for x in i]

那应该从 i 中得到一个舍入值列表。

您还可以使用 map 函数：

list(map(lambda x: math.floor(float(x)), i))

Answer 2

math.floor() only accepts a single float value argument (or an object with a __floor__() method). To apply it (or another callable taking a single argument) to a whole list you can use list comprehensions如下图：

import math

with open('december.sorted.movement.Sample.txt', 'r') as f:
    first_line = next(f)
    split = first_line.split('\t')

    Speeds = [float(line.split()[5]) for line in f]
    denominator = 8677.8
    v = [math.floor(sp / denominator) for sp in Speeds]
    print(v[:5])

如果您不需要 Speeds 列表来做任何其他事情，您甚至可以将两个列表理解合并为一个并执行如下操作（尽管它的可读性较差）：

with open('december.sorted.movement.Sample.txt', 'r') as f:
    first_line = next(f)
    split = first_line.split('\t')

    denominator = 8677.8
    v = [math.floor(float(line.split()[5] )/ denominator) for line in f]
    print(v[:5])

四舍五入的浮点数列表？

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