TypeError: list indices must be integers or slices, not list
<p>array = some kind of list with 3 columns and unlimited amount of rows with data inside of it.</p>

<pre><code>Volume = array[0][2] 
counter = 0
for i in array: 
    if Volume == array[i][2]: #&lt;------ why is this line a problem? 
        counter += 1
</code></pre>