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copied!<p>The functionality of <code>map</code> and <code>filter</code> was intentionally changed to return iterators, and reduce was removed from being a built-in and placed in <code>functools.reduce</code>.</p> <p>So, for <code>filter</code> and <code>map</code>, you can wrap them with <code>list()</code> to see the results like you did before.</p> <pre><code>>>> def f(x): return x % 2 != 0 and x % 3 != 0 ... >>> list(filter(f, range(2, 25))) [5, 7, 11, 13, 17, 19, 23] >>> def cube(x): return x*x*x ... >>> list(map(cube, range(1, 11))) [1, 8, 27, 64, 125, 216, 343, 512, 729, 1000] >>> import functools >>> def add(x,y): return x+y ... >>> functools.reduce(add, range(1, 11)) 55 >>> </code></pre> <p>The recommendation now is that you replace your usage of map and filter with generators expressions or list comprehensions. Example:</p> <pre><code>>>> def f(x): return x % 2 != 0 and x % 3 != 0 ... >>> [i for i in range(2, 25) if f(i)] [5, 7, 11, 13, 17, 19, 23] >>> def cube(x): return x*x*x ... >>> [cube(i) for i in range(1, 11)] [1, 8, 27, 64, 125, 216, 343, 512, 729, 1000] >>> </code></pre> <p>They say that for loops are 99 percent of the time easier to read than reduce, but I'd just stick with <code>functools.reduce</code>.</p> <p><strong>Edit</strong>: The 99 percent figure is pulled directly from the <a href="https://docs.python.org/3.0/whatsnew/3.0.html" rel="noreferrer" title="What’s New In Python 3.0">What’s New In Python 3.0</a> page authored by Guido van Rossum.</p>

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