转换为二进制并保留前导零 [英] Convert to binary and keep leading zeros

问题描述

我正在尝试使用 Python 中的 bin() 函数将整数转换为二进制.但是，它总是删除我实际需要的前导零，因此结果始终为 8 位:

示例:

bin(1) ->0b1# 我想要什么:bin(1) ->0b00000001

有没有办法做到这一点?

解决方案

使用 format() 函数:

<预><代码>>>>格式(14，'#010b')'0b00001110'

format() 函数只是按照 格式规范迷你语言.# 使格式包含 0b 前缀，010 大小将输出格式化为适合 10 个字符的宽度，0 填充；0b 前缀 2 个字符，二进制数字 8 个字符.

这是最紧凑、最直接的选择.

如果您将结果放在更大的字符串中，请使用 格式化字符串文字 (3.6+) 或使用 str.format() 并将 format() 函数的第二个参数放在占位符的冒号之后 {:...}:<预><代码>>>>值 = 14>>>f'生成的二进制输出为:{value:#010b}''产生的输出，以二进制表示:0b00001110'>>>'产生的输出，以二进制表示:{:#010b}'.format(value)'产生的输出，以二进制表示:0b00001110'

碰巧的是，即使只是格式化单个值(因此无需将结果放入更大的字符串中)，使用格式化的字符串文字也比使用format() 更快:

<预><代码>>>>导入时间>>>timeit.timeit("f_(v, '#010b')", "v = 14; f_ = format") # 使用本地的性能0.40298633499332936>>>timeit.timeit("f'{v:#010b}'", "v = 14")0.2850222919951193

但只有在紧密循环中的性能很重要时我才会使用它，因为 format(...) 可以更好地传达意图.

如果您不需要 0b 前缀，只需删除 # 并调整字段的长度:

<预><代码>>>>格式(14，'08b')'00001110'

I'm trying to convert an integer to binary using the bin() function in Python. However, it always removes the leading zeros, which I actually need, such that the result is always 8-bit:

Example:

bin(1) -> 0b1

# What I would like:
bin(1) -> 0b00000001

Is there a way of doing this?

解决方案

Use the format() function:

>>> format(14, '#010b')
'0b00001110'

The format() function simply formats the input following the Format Specification mini language. The # makes the format include the 0b prefix, and the 010 size formats the output to fit in 10 characters width, with 0 padding; 2 characters for the 0b prefix, the other 8 for the binary digits.

This is the most compact and direct option.

If you are putting the result in a larger string, use an formatted string literal (3.6+) or use str.format() and put the second argument for the format() function after the colon of the placeholder {:..}:

>>> value = 14
>>> f'The produced output, in binary, is: {value:#010b}'
'The produced output, in binary, is: 0b00001110'
>>> 'The produced output, in binary, is: {:#010b}'.format(value)
'The produced output, in binary, is: 0b00001110'

As it happens, even for just formatting a single value (so without putting the result in a larger string), using a formatted string literal is faster than using format():

>>> import timeit
>>> timeit.timeit("f_(v, '#010b')", "v = 14; f_ = format")  # use a local for performance
0.40298633499332936
>>> timeit.timeit("f'{v:#010b}'", "v = 14")
0.2850222919951193

But I'd use that only if performance in a tight loop matters, as format(...) communicates the intent better.

If you did not want the 0b prefix, simply drop the # and adjust the length of the field:

>>> format(14, '08b')
'00001110'

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