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one more section of advanced-iterators

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Mark Pilgrim
2009-04-22 23:29:08 -04:00
parent 4afb4d3e69
commit 1739c7aa2a
1 changed files with 8 additions and 4 deletions
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advanced-iterators.html
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@@ -82,14 +82,18 @@ if __name__ == '__main__':
<h2 id=re-findall>Finding all occurrences of a pattern</h2>
<p>FIXME
<p>The first thing this alphametics solver does is find all the letters (A&ndash;Z) in the puzzle.
<pre class=screen>
<samp class=p>>>> </samp><kbd>import re</kbd>
<samp class=p>>>> </samp><kbd>re.findall('[A-Z]+', 'SEND + MORE == MONEY')</kbd>
<a><samp class=p>>>> </samp><kbd>re.findall('[0-9]+', '16 2-by-4s in rows of 8')</kbd> <span>&#x2460;</span></a>
<samp>['16', '2', '4', '8']</samp>
<a><samp class=p>>>> </samp><kbd>re.findall('[A-Z]+', 'SEND + MORE == MONEY')</kbd> <span>&#x2461;</span></a>
<samp>['SEND', 'MORE', 'MONEY']</samp></pre>
<p>FIXME
<ol>
<li>The <code>re</code> module is Python's implementation of <a href=regular-expressions.html>regular expressions</a>. It has a nifty function called <code>findall()</code> which takes a regular expression pattern and a string, and finds all occurrences of the pattern within the string. In this case, the pattern matches sequences of numbers. The <code>findall()</code> function returns a list of all the substrings that matched the pattern.
<li>Here the regular expression pattern matches sequences of letters. Again, the return value is a list, and each item in the list is a string that matched the regular expression pattern.
</ol>
<h2 id=unique-items>Finding the unique items in a sequence</h2>