How to use a function to change a list when passed by reference?
<p>The code is passed an array. My understanding is this passing is done by reference. I want the function to recursively divide the last remaining half of the list in two and set each value that it was split at to zero.
The change to zero is happens in the array but when I call print a at the end I get the original array.</p>

<p>What am i doing wrong?</p>

<pre><code>a = range(10)

def listreduction(array):
    if len(array) == 1:
        array[0] = 0
        return

    split = len(array)/2
    array[split] = 0

    return listreduction(array[split:])

listreduction(a)
print a
</code></pre>

<p>The current output is </p>

<pre><code>[0, 1, 2, 3, 4, 0, 6, 7, 8, 9]
</code></pre>

<p>The should be more zeros to the right of the second one</p>

<p>A slice creates a new list. If you want to do this recursively, you'll have to pass the index where the function is supposed to work on the list, not the actual slice.</p>

python list