红宝石正则表达式来替换方程式 [英] ruby regexp to replace equations

问题描述

我有一些用mathjax格式的HTML文本:

I have a some HTML text in mathjax format:

text = "an inline \\( f(x) = \frac{a}{b} \\) equation, a display equation \\[ F = m a \\] \n and another inline \\(y = x\\)"

(注意:方程式由单斜杠分隔，例如\(，而不是\\(，多余的\只是转义第一个红宝石文本).

(Note: equations are delimited by single slashes, e.g. \(, not \\(, the extra \ is just escaping the first one for ruby text).

我想获得将其替代的输出，例如由latex.codecogs创建的图像，例如

I want to get the output that substitutes this into, say an image created by latex.codecogs, e.g.

desired_output = "an inline <img src="http://latex.codecogs.com/png.latex?f(x) = \frac{a}{b}\inline"/> equation, a display equation <img src="http://latex.codecogs.com/png.latex?F = m a"/> \n and another inline <img src="http://latex.codecogs.com/png.latex?y = x\inline"/> "

使用Ruby.我尝试:

Using Ruby. I try:

desired = text.gsub("(\\[)(.*?)(\\])", "<img src=\"http://latex.codecogs.com/png.latex?\2\" />") 
desired = desired.gsub("(\\()(.*?)(\\))", "<img src=\"http://latex.codecogs.com/png.latex?\2\\inline\")
desired

但这是不成功的，仅返回原始输入.我错过了什么?如何适当地构造此查询?

But this is unsuccessful, returning only the original input. What did I miss? How do I construct this query appropriately?

推荐答案

尝试:

desired = text.gsub(/\\\[\s*(.*?)\s*\\\]/, "<img src=\"http://latex.codecogs.com/png.latex?\\1\"/>") 
desired = desired.gsub(/\\\(\s*(.*?)\s*\\\)/, "<img src=\"http://latex.codecogs.com/png.latex?\\1\inline\"/>")
desired

必须发生的重要变化:

• gsub的第一个参数应为正则表达式(如Anthony所述)
• 如果第二个参数是用双引号引起来的字符串，则后向引用必须类似于\\2(而不只是\2)(请参见

• The first parameter for gsub should be a regex (as Anthony mentioned)
• If the second parameter is a double-quoted string, then the back references have to be like \\2 (instead of just \2) (see the rdoc)
• The first parameter was not escaping the \

还有其他一些次要格式化内容(空格等).

There were a couple of other minor formatting things (spaces, etc).

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