title: What does each item mean in svmLight Format
body: <p>I am very confused about what each part means in a svmLight data format.
  For example:</p>
  
  <p>(label/target, [(feature, value), ...], queryid)</p>
  
  <p>Does the label means the rank of the data and queryid is the id of the object?</p>
  
  <p>For example:
  for the following item:</p>
  
  <p>2 qid:1 1:4.000000 2:2.772589 3:0.266667 4:0.258154 5:37.330565 6:11.431241 7:37.307017 8:1.213630 9:21.342267 10:10.842279 11:15.634736 12:2.749495 13:-39.467448 14:-37.791635 15:-38.002289 16:14.000000 17:5.634790 18:0.063927 19:0.063290 20:28.303065 21:9.340024 22:24.809801 23:0.231553 24:52.396216 25:1.692954 26:16.619600 27:2.810583 28:-45.733775 29:-44.612550 30:-44.823263 31:18.000000 32:6.579251 33:0.076923 34:0.076079 35:27.701632 36:9.139690 37:23.819476 38:0.277200 39:67.283604 40:1.847508 41:19.559974 42:2.973485 43:-44.687666 44:-43.467574 45:-43.302044 #docid = 346319</p>
  
  <p>Does 2 means the rank/ the target value of the object? Then what does qid or docid means for the file?</p>
  
  <p>Thank you!</p>