Fastest way to remove all multiple occurrence items from a list?
<p>What is the fastest way to remove all multiple occurrence items from a list of arbitrary items (in my example a list of lists)? In the result, only items that occur a single time in the list should show up, thus removing all duplicates.</p>

<p>input: [[1, 2], [1, 3], [1, 4], [1, 2], [1, 4], [1, 2]]</p>

<p>output: [[1, 3], ]</p>

<p>This solution was slow:</p>

<pre><code>output = [item for item in input if input.count(item)==1]
</code></pre>

<p>This solution was faster:</p>

<pre><code>duplicates = []
output = []
for item in input:
    if not item in duplicates:
        if item in output:
            output.remove(item)
            duplicates.append(item)
        else:
           output.append(item)
</code></pre>

<p>Is there any better solution, probably by first sorting the list? Any ideas are appreciated.</p>
