在Python中为ANSI颜色代码的字符串获取正确的字符串长度 [英] Getting correct string length in Python for strings with ANSI color codes

问题描述

我有一些Python代码将自动以漂亮的列格式打印一组数据，包括放入适当的ASCII转义序列来绘制各种数据以便阅读。

I've got some Python code that will automatically print a set of data in a nice column format, including putting in the appropriate ASCII escape sequences to color various pieces of the data for readability.

我最终以每行表示为列表，每个项目是一个空格填充的列，因此每行上的相同列总是相同的长度。不幸的是，当我真的打印这个，不是所有的列排列。我怀疑这是与ASCII转义序列有关 - 因为 len 函数似乎不能识别这些：

I eventually end up with each line being represented as a list, with each item being a column that is space-padded so that the same columns on each line are always the same length. Unfortunately when I actually go to print this, not all the columns line up. I suspect this is to do with the ASCII escape sequences - because the len function doesn't seem to recognize these:

>>> a = '\x1b[1m0.0\x1b[0m'
>>> len(a)
11
>>> print a
0.0

所以每个列的长度根据 len ，它们在屏幕上打印时的长度实际上不一样。

And so while each column is the same length according to len, they are not actually the same length when printed on the screen.

有没有办法（除了使用正则表达式做一些黑客，我宁愿不做）采取转义的字符串，找出打印长度是什么我可以适当的太空垫？也许有些方法只是打印回到字符串并检查其长度？

Is there any way (save for doing some hackery with regular expressions which I'd rather not do) to take the escaped string and find out what the printed length is so I can space pad appropriately? Maybe some way to just "print" it back to string and examine the length of that?

推荐答案

这个pyparsing wiki包含这个<对于ANSI转义序列进行匹配，href =http://pyparsing-public.wikispaces.com/Helpful+Expressions#toc7 =noreferrer>有用表达式

The pyparsing wiki includes this helpful expression for matching on ANSI escape sequences:

ESC = Literal('\x1b')
integer = Word(nums)
escapeSeq = Combine(ESC + '[' + Optional(delimitedList(integer,';')) + 
                oneOf(list(alphas)))

这是如何使它成为一个逃脱序列剥离器：

Here's how to make this into an escape-sequence-stripper:

from pyparsing import *

ESC = Literal('\x1b')
integer = Word(nums)
escapeSeq = Combine(ESC + '[' + Optional(delimitedList(integer,';')) + 
                oneOf(list(alphas)))

nonAnsiString = lambda s : Suppress(escapeSeq).transformString(s)

unColorString = nonAnsiString('\x1b[1m0.0\x1b[0m')
print unColorString, len(unColorString)

打印：

0.0 3

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