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copied!<p>The problem with using</p> <pre><code>re.sub(r'_thing_', temp, template) </code></pre> <p>is that <em>every</em> occurrence of <code>_thing_</code> is getting replaced with the same value, <code>temp</code>.</p> <p>What we desire for here is a <code>temp</code> value that can change with each match. </p> <p><a href="http://docs.python.org/2/library/re.html#re.sub" rel="nofollow"><code>re.sub</code> provides such a facility</a> through the use of a callback function as the second argument, rather than a string like <code>temp</code>.</p> <p>The callback is simply a function that takes one argument, the match object, and returns the string we desire for that match.</p> <pre><code>def replacer(match): return ... </code></pre> <p>Now what to put in place of the ellipsis? We can use an <code>iter</code> here:</p> <pre><code>In [27]: math6 = ['chapter1', 'chapter2', 'chapter3', 'chapter1-3test'] In [28]: math6 = iter(math6) In [29]: next(math6) Out[29]: 'chapter1' In [30]: next(math6) Out[30]: 'chapter2' </code></pre> <p>So what we really want is a callback that looks like this:</p> <pre><code>def replacer(match): return next(data) </code></pre> <p>But we have more than one set of data: <code>math6</code> and <code>math4</code>, for example. So we need a callback factory: a function that returns a callback given <code>data</code>:</p> <pre><code>def replace_with(data): def replacer(match): return next(data) return replacer </code></pre> <hr> <p>Putting it all together,</p> <pre><code>import re math6 = iter(['chapter1', 'chapter2', 'chapter3', 'chapter1-3test']) math4 = iter(['chapter1.1', 'chapter1.2-3', 'chapter2']) text = r''' \begin{tabular}{|p{0.7in}|p{0.8in}|p{2.2in}|p{.9in}|p{2.6in}|p{1.6in}|} 6${}^{th}$ Math \newline M\newline & _math6_& 6${}^{th}$ Math \newline W \newline & _math6_ & 6${}^{th}$ Math \newline F \newline & _math6_ & 4${}^{th}$ Math \newline M\newline & & _math4_ & 4${}^{th}$ Math \newline W\newline & & _math4_ & \end{tabular} ''' def replace_with(data): def replacer(match): return next(data) return replacer for pat, data in [(r'_math6_', math6), (r'_math4_', math4)]: text = re.sub(pat, replace_with(data), text) print(text) </code></pre> <p>yields</p> <pre><code>\begin{tabular}{|p{0.7in}|p{0.8in}|p{2.2in}|p{.9in}|p{2.6in}|p{1.6in}|} 6${}^{th}$ Math \newline M\newline & chapter1& 6${}^{th}$ Math \newline W \newline & chapter2 & 6${}^{th}$ Math \newline F \newline & chapter3 & 4${}^{th}$ Math \newline M\newline & & chapter1.1 & 4${}^{th}$ Math \newline W\newline & & chapter1.2-3 & \end{tabular} </code></pre>

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