 <p>For the first question:</p> <pre><code>my_indices_set = set(my_indices) [i for i, x in enumerate(my_array) if i not in my_indices] </code></pre> <p>For the second question:</p> <pre><code>[x for x in my_array if x not in my_indices_set] </code></pre> <p>It's more efficient if we use sets, but then there's the cost of creating the sets in the first place</p>