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<H2><A NAME="SECTION0071620000000000000000"></A><A NAME="itertools-example"></A>
<BR>
5.16.2 Examples
</H2>

<P>
The following examples show common uses for each tool and
demonstrate ways they can be combined.

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; amounts = [120.15, 764.05, 823.14]
&gt;&gt;&gt; for checknum, amount in izip(count(1200), amounts):
...     print 'Check %d is for $%.2f' % (checknum, amount)
...
Check 1200 is for $120.15
Check 1201 is for $764.05
Check 1202 is for $823.14

&gt;&gt;&gt; import operator
&gt;&gt;&gt; for cube in imap(operator.pow, xrange(1,5), repeat(3)):
...    print cube
...
1
8
27
64

&gt;&gt;&gt; reportlines = ['EuroPython', 'Roster', '', 'alex', '', 'laura',
                  '', 'martin', '', 'walter', '', 'mark']
&gt;&gt;&gt; for name in islice(reportlines, 3, None, 2):
...    print name.title()
...
Alex
Laura
Martin
Walter
Mark

# Show a dictionary sorted and grouped by value
&gt;&gt;&gt; from operator import itemgetter
&gt;&gt;&gt; d = dict(a=1, b=2, c=1, d=2, e=1, f=2, g=3)
&gt;&gt;&gt; di = sorted(d.iteritems(), key=itemgetter(1))
&gt;&gt;&gt; for k, g in groupby(di, key=itemgetter(1)):
...     print k, map(itemgetter(0), g)
...
1 ['a', 'c', 'e']
2 ['b', 'd', 'f']
3 ['g']

# Find runs of consecutive numbers using groupby.  The key to the solution
# is differencing with a range so that consecutive numbers all appear in
# same group.
&gt;&gt;&gt; data = [ 1,  4,5,6, 10, 15,16,17,18, 22, 25,26,27,28]
&gt;&gt;&gt; for k, g in groupby(enumerate(data), lambda (i,x):i-x):
...     print map(operator.itemgetter(1), g)
...
[1]
[4, 5, 6]
[10]
[15, 16, 17, 18]
[22]
[25, 26, 27, 28]
</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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