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<H2><A NAME="SECTION006440000000000000000"></A><A NAME="differ-examples"></A>
<BR>
4.4.4 Differ Example
</H2>

<P>
This example compares two texts. First we set up the texts, sequences
of individual single-line strings ending with newlines (such sequences
can also be obtained from the <tt class="method">readlines()</tt> method of file-like
objects):

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; text1 = '''  1. Beautiful is better than ugly.
...   2. Explicit is better than implicit.
...   3. Simple is better than complex.
...   4. Complex is better than complicated.
... '''.splitlines(1)
&gt;&gt;&gt; len(text1)
4
&gt;&gt;&gt; text1[0][-1]
'\n'
&gt;&gt;&gt; text2 = '''  1. Beautiful is better than ugly.
...   3.   Simple is better than complex.
...   4. Complicated is better than complex.
...   5. Flat is better than nested.
... '''.splitlines(1)
</pre></div>

<P>
Next we instantiate a Differ object:

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; d = Differ()
</pre></div>

<P>
Note that when instantiating a <tt class="class">Differ</tt> object we may pass
functions to filter out line and character ``junk.''  See the
<tt class="method">Differ()</tt> constructor for details.

<P>
Finally, we compare the two:

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; result = list(d.compare(text1, text2))
</pre></div>

<P>
<code>result</code> is a list of strings, so let's pretty-print it:

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; from pprint import pprint
&gt;&gt;&gt; pprint(result)
['    1. Beautiful is better than ugly.\n',
 '-   2. Explicit is better than implicit.\n',
 '-   3. Simple is better than complex.\n',
 '+   3.   Simple is better than complex.\n',
 '?     ++                                \n',
 '-   4. Complex is better than complicated.\n',
 '?            ^                     ---- ^  \n',
 '+   4. Complicated is better than complex.\n',
 '?           ++++ ^                      ^  \n',
 '+   5. Flat is better than nested.\n']
</pre></div>

<P>
As a single multi-line string it looks like this:

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; import sys
&gt;&gt;&gt; sys.stdout.writelines(result)
    1. Beautiful is better than ugly.
-   2. Explicit is better than implicit.
-   3. Simple is better than complex.
+   3.   Simple is better than complex.
?     ++
-   4. Complex is better than complicated.
?            ^                     ---- ^
+   4. Complicated is better than complex.
?           ++++ ^                      ^
+   5. Flat is better than nested.
</pre></div>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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