mirror of
https://github.com/kennethreitz/dive-into-python3.git
synced 2026-06-05 23:10:17 +00:00
colorize interactive shell examples
This commit is contained in:
Mark Pilgrim
+34
-34
@@ -56,15 +56,15 @@ def plural(noun):
|
||||
|
||||
<p>Let’s look at regular expression substitutions in more detail.
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>import re</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>re.search('[abc]', 'Mark')</kbd> <span class=u>①</span></a>
|
||||
<samp class=p>>>> </samp><kbd class=pp>import re</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.search('[abc]', 'Mark')</kbd> <span class=u>①</span></a>
|
||||
<_sre.SRE_Match object at 0x001C1FA8>
|
||||
<a><samp class=p>>>> </samp><kbd>re.sub('[abc]', 'o', 'Mark')</kbd> <span class=u>②</span></a>
|
||||
<samp>'Mork'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>re.sub('[abc]', 'o', 'rock')</kbd> <span class=u>③</span></a>
|
||||
<samp>'rook'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>re.sub('[abc]', 'o', 'caps')</kbd> <span class=u>④</span></a>
|
||||
<samp>'oops'</samp></pre>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.sub('[abc]', 'o', 'Mark')</kbd> <span class=u>②</span></a>
|
||||
<samp class=pp>'Mork'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.sub('[abc]', 'o', 'rock')</kbd> <span class=u>③</span></a>
|
||||
<samp class=pp>'rook'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.sub('[abc]', 'o', 'caps')</kbd> <span class=u>④</span></a>
|
||||
<samp class=pp>'oops'</samp></pre>
|
||||
<ol>
|
||||
<li>Does the string <code>Mark</code> contain <code>a</code>, <code>b</code>, or <code>c</code>? Yes, it contains <code>a</code>.
|
||||
<li>OK, now find <code>a</code>, <code>b</code>, or <code>c</code>, and replace it with <code>o</code>. <code>Mark</code> becomes <code>Mork</code>.
|
||||
@@ -92,14 +92,14 @@ def plural(noun):
|
||||
<p>Let’s look at negation regular expressions in more detail.
|
||||
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>import re</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>re.search('[^aeiou]y$', 'vacancy')</kbd> <span class=u>①</span></a>
|
||||
<samp class=p>>>> </samp><kbd class=pp>import re</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.search('[^aeiou]y$', 'vacancy')</kbd> <span class=u>①</span></a>
|
||||
<_sre.SRE_Match object at 0x001C1FA8>
|
||||
<a><samp class=p>>>> </samp><kbd>re.search('[^aeiou]y$', 'boy')</kbd> <span class=u>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.search('[^aeiou]y$', 'boy')</kbd> <span class=u>②</span></a>
|
||||
<samp class=p>>>> </samp>
|
||||
<samp class=p>>>> </samp><kbd>re.search('[^aeiou]y$', 'day')</kbd>
|
||||
<samp class=p>>>> </samp><kbd class=pp>re.search('[^aeiou]y$', 'day')</kbd>
|
||||
<samp class=p>>>> </samp>
|
||||
<a><samp class=p>>>> </samp><kbd>re.search('[^aeiou]y$', 'pita')</kbd> <span class=u>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.search('[^aeiou]y$', 'pita')</kbd> <span class=u>③</span></a>
|
||||
<samp class=p>>>> </samp></pre>
|
||||
<ol>
|
||||
<li><code>vacancy</code> matches this regular expression, because it ends in <code>cy</code>, and <code>c</code> is not <code>a</code>, <code>e</code>, <code>i</code>, <code>o</code>, or <code>u</code>.
|
||||
@@ -107,12 +107,12 @@ def plural(noun):
|
||||
<li><code>pita</code> does not match, because it does not end in <code>y</code>.
|
||||
</ol>
|
||||
<pre class=screen>
|
||||
<a><samp class=p>>>> </samp><kbd>re.sub('y$', 'ies', 'vacancy')</kbd> <span class=u>①</span></a>
|
||||
<samp>'vacancies'</samp>
|
||||
<samp class=p>>>> </samp><kbd>re.sub('y$', 'ies', 'agency')</kbd>
|
||||
<samp>'agencies'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>re.sub('([^aeiou])y$', r'\1ies', 'vacancy')</kbd> <span class=u>②</span></a>
|
||||
<samp>'vacancies'</samp></pre>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.sub('y$', 'ies', 'vacancy')</kbd> <span class=u>①</span></a>
|
||||
<samp class=pp>'vacancies'</samp>
|
||||
<samp class=p>>>> </samp><kbd class=pp>re.sub('y$', 'ies', 'agency')</kbd>
|
||||
<samp class=pp>'agencies'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>re.sub('([^aeiou])y$', r'\1ies', 'vacancy')</kbd> <span class=u>②</span></a>
|
||||
<samp class=pp>'vacancies'</samp></pre>
|
||||
<ol>
|
||||
<li>This regular expression turns <code>vacancy</code> into <code>vacancies</code> and <code>agency</code> into <code>agencies</code>, which is what you wanted. Note that it would also turn <code>boy</code> into <code>boies</code>, but that will never happen in the function because you did that <code>re.search</code> first to find out whether you should do this <code>re.sub</code>.
|
||||
<li>Just in passing, I want to point out that it is possible to combine these two regular expressions (one to find out if the rule applies, and another to actually apply it) into a single regular expression. Here’s what that would look like. Most of it should look familiar: you’re using a remembered group, which you learned in <a href=regular-expressions.html#phonenumbers>Case study: Parsing Phone Numbers</a>. The group is used to remember the character before the letter <code>y</code>. Then in the substitution string, you use a new syntax, <code>\1</code>, which means “hey, that first group you remembered? put it right here.” In this case, you remember the <code>c</code> before the <code>y</code>; when you do the substitution, you substitute <code>c</code> in place of <code>c</code>, and <code>ies</code> in place of <code>y</code>. (If you have more than one remembered group, you can use <code>\2</code> and <code>\3</code> and so on.)
|
||||
@@ -313,23 +313,23 @@ def plural(noun):
|
||||
<p>How the heck does <em>that</em> work? Let’s look at an interactive example first.
|
||||
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>def make_counter(x):</kbd>
|
||||
<samp class=p>... </samp><kbd> print('entering make_counter')</kbd>
|
||||
<samp class=p>... </samp><kbd> while True:</kbd>
|
||||
<a><samp class=p>... </samp><kbd> yield x</kbd> <span class=u>①</span></a>
|
||||
<samp class=p>... </samp><kbd> print('incrementing x')</kbd>
|
||||
<samp class=p>... </samp><kbd> x = x + 1</kbd>
|
||||
<samp class=p>>>> </samp><kbd class=pp>def make_counter(x):</kbd>
|
||||
<samp class=p>... </samp><kbd class=pp> print('entering make_counter')</kbd>
|
||||
<samp class=p>... </samp><kbd class=pp> while True:</kbd>
|
||||
<a><samp class=p>... </samp><kbd class=pp> yield x</kbd> <span class=u>①</span></a>
|
||||
<samp class=p>... </samp><kbd class=pp> print('incrementing x')</kbd>
|
||||
<samp class=p>... </samp><kbd class=pp> x = x + 1</kbd>
|
||||
<samp class=p>... </samp>
|
||||
<a><samp class=p>>>> </samp><kbd>counter = make_counter(2)</kbd> <span class=u>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>counter</kbd> <span class=u>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>counter = make_counter(2)</kbd> <span class=u>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>counter</kbd> <span class=u>③</span></a>
|
||||
<generator object at 0x001C9C10>
|
||||
<a><samp class=p>>>> </samp><kbd>next(counter)</kbd> <span class=u>④</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>next(counter)</kbd> <span class=u>④</span></a>
|
||||
<samp>entering make_counter
|
||||
2</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>next(counter)</kbd> <span class=u>⑤</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>next(counter)</kbd> <span class=u>⑤</span></a>
|
||||
<samp>incrementing x
|
||||
3</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>next(counter)</kbd> <span class=u>⑥</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>next(counter)</kbd> <span class=u>⑥</span></a>
|
||||
<samp>incrementing x
|
||||
4</samp></pre>
|
||||
<ol>
|
||||
@@ -362,10 +362,10 @@ def plural(noun):
|
||||
<p>So you have a function that spits out successive Fibonacci numbers. Sure, you could do that with recursion, but this way is easier to read. Also, it works well with <code>for</code> loops.
|
||||
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>from fibonacci import fib</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>for n in fib(1000):</kbd> <span class=u>①</span></a>
|
||||
<a><samp class=p>... </samp><kbd> print(n, end=' ')</kbd> <span class=u>②</span></a>
|
||||
<samp>0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987</samp></pre>
|
||||
<samp class=p>>>> </samp><kbd class=pp>from fibonacci import fib</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd class=pp>for n in fib(1000):</kbd> <span class=u>①</span></a>
|
||||
<a><samp class=p>... </samp><kbd class=pp> print(n, end=' ')</kbd> <span class=u>②</span></a>
|
||||
<samp class=pp>0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987</samp></pre>
|
||||
<ol>
|
||||
<li>You can use a generator like <code>fib()</code> in a <code>for</code> loop directly. The <code>for</code> loop will automatically call the <code>next()</code> function to get values from the <code>fib()</code> generator and assign them to the <code>for</code> loop index variable (<var>n</var>).
|
||||
<li>Each time through the <code>for</code> loop, <var>n</var> gets a new value from the <code>yield</code> statement in <code>fib()</code>, and all you have to do is print it out. Once <code>fib()</code> runs out of numbers (<var>a</var> becomes bigger than <var>max</var>, which in this case is <code>1000</code>), then the <code>for</code> loop exits gracefully.
|
||||
|
||||
Reference in New Issue
Block a user