返回信息流formula = re.sub('\\\\begin{vmatrix}', '\\left|\\matrix{' , formula)
formula = re.sub('\\\\end{vmatrix}', '\\cr}\\\\right|' , formula)
formula = re.sub('\\\\\\\\', '\\cr ' , formula)
The above python snippet works, it translates LaTeX struct '\begin{vmatrix} ... \end{vmatrix}' to its plain TeX counterpart '\left\|\matrix{ ... }\right|'.
Why there are two backslashes before 'left' but four before 'right'?
这是一条镜像帖。来源：北邮人论坛 / python / #1106同步于 2014/6/18
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[问题] 快下班了，问个问题
SinceBelieve
2014/6/18镜像同步2 回复
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2 条回复
哪里复制的问题还用英文- -
正则表达式转义本来就显得特别啰嗦 建议用rawstr少几个转义
r''
这里r多几个\\的原因应该是\r是有意义的导致的
What you see: \\\\
In the Python string literal grammar, two backslashes in quotes '\\' mean a single backslash character.
What Python sees and also what the RE engine sees: \\
In the RE grammar, two backslashes match a single backslash.
What the RE engine matches: \