title: Group into sublists with common values of a column from list of list
body: <p>List element format: (x0, y0, x1, y1, "word", block_no, line_no, word_no)</p>
  
  <pre><code>given = [
  (518.1566162109375, 381.6667175292969, 537.3801879882812, 391.70867919921875, 'cost', 19, 0, 11), 
  (542.1559448242188, 381.6667175292969, 556.5796508789062, 391.70867919921875, 'and', 19, 0, 12), 
  (81.36001586914062, 390.6634826660156, 124.58306121826172, 400.7054443359375, 'inventory', 19, 1, 0), 
  (129.35882568359375, 390.6634826660156, 167.78199768066406, 400.7054443359375, 'control,', 19, 1, 1)
  ]
  </code></pre>
  
  <p>I need to group by "y1" with the same values and form as given below:</p>
  
  <pre><code>required = [
  [
  (518.1566162109375, 381.6667175292969, 537.3801879882812, 391.70867919921875, 'cost', 19, 0, 11), 
  (542.1559448242188, 381.6667175292969, 556.5796508789062, 391.70867919921875, 'and', 19, 0, 12)
  ], 
  [
  (81.36001586914062, 390.6634826660156, 124.58306121826172, 400.7054443359375, 'inventory', 19, 1, 0), 
  (129.35882568359375, 390.6634826660156, 167.78199768066406, 400.7054443359375, 'control,', 19, 1, 1)
  ]
  ]
  </code></pre>
  
  <p>Please suggest me some best way to achieve it.</p>