Python 字符串格式化:填充负数 [英] Python string formatting: padding negative numbers

问题描述

我想将我的整数格式化为字符串，以便在没有符号的情况下，它们将被零填充以至少包含两位数字.

I would like to format my integers as strings so that, without the sign, they will be zero-padded to have at least two digits.

例如我想要

1
-1
10
-10

成为

01
-01
10
-10

具体来说，我希望负数 (3) 和非负数 (2) 的最小字符串长度不同.此处 中的简单数字填充是不够的.这可能吗?

Specifically, I want different minimum string lengths for negative numbers (3) and non-negative numbers (2). Simple number padding as detailed here is insufficient. Is this possible?

推荐答案

您可以使用 str.format，但在大小上加 1 以将负数考虑在内:

you could use str.format, but adding 1 to the size to take the negative number into account here:

l = [1,-1,10,-10,4]

new_l = ["{1:0{0}d}".format(2 if x>=0 else 3,x) for x in l]

print(new_l)

结果:

['01', '-01', '10', '-10', '04']

之所以有效，是因为 format 接受嵌套表达式:您可以将大小 ({:02d} 或 {:03d}) 作为格式项也省去了第一遍格式化格式字符串的麻烦.

it works because format accepts nested expressions: you can pass the size ({:02d} or {:03d}) as a format item too when saves the hassle of formatting the format string in a first pass.

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