title: How to get if an element in numpy array, for indexing?
body: <p>I tried to find this question but did not find. If there is an answer then please merge it with that.
  I have a numpy array,</p>
  <pre><code> array_1 = array([array([2, 4, 7, 9]), array([5, 8]), array([3, 4, 7, 9]),
     array([ 2,  3,  5,  6,  8,  9, 10]), array([8]), array([ 1, 10]),
     array([ 4,  6,  7,  8, 10]), array([3, 5, 6, 7, 8]),
     array([1, 4, 6, 7, 9]), array([1, 5, 6, 7, 8]),
     array([1, 2, 5, 6]), array([2, 3]), array([6]), array([4, 8]),
     array([1, 8, 9])], dtype=object)
  </code></pre>
  <p>I want to find if 4 is in array or not. I am expecting for <code>&gt;&gt;[True, False, True, False, False, False, True, False, True, False, False, False, False, True, False]</code>. I want to use it for indexing purpose. The array is 3-dimensional and I want to choose instances where 4 is in the middle column. I do not want to use loop or any alternatives which makes code slower. It is a part for a complex program. For reference purpose, I am attaching entire array:</p>
  <pre><code>array([[105, array([2, 4, 7, 9]), 100],
     [120, array([5, 8]), 100],
     [110, array([3, 4, 7, 9]), 100],
     [105, array([ 2,  3,  5,  6,  8,  9, 10]), 100],
     [135, array([8]), 100],
     [115, array([ 4,  6,  7,  8, 10]), 100],
     [110, array([3, 5, 6, 7, 8]), 100],
     [105, array([2, 3]), 100],
     [125, array([6]), 100],
     [115, array([4, 8]), 100]], dtype=object)
  </code></pre>