title: How to find the minimum value from a part of a column in numpy array?
body: <p>I have a numpy array like below, which has three columns, col.1 is the distance, col. 2 and 3 are the id of the nodes. I want to find the minimum distance from the 1st column but only for node id 0. </p>
  
  <pre><code>distance   i    j
  [[ 1.18801546  0.          1.        ]
   [ 2.30434659  0.          2.        ]
   [ 3.46650731  0.          3.        ]
   [ 0.85449778  0.          4.        ]
   [ 0.84375971  0.          5.        ]
   [ 2.66327706  0.          6.        ]
   [ 1.84376278  0.          7.        ]
   [ 1.29614483  0.          8.        ]
   [ 2.86955783  0.          9.        ]
   [ 1.55222839  1.          2.        ]
   [ 2.56904021  1.          3.        ]
   [ 0.56480212  1.          4.        ]
   [ 0.81877367  1.          5.        ]
   [ 2.87466569  1.          6.        ]
   [ 1.01649384  1.          7.        ]
   [ 1.95662814  1.          8.        ]
   [ 3.15455155  1.          9.        ]
   [ 1.1897445   2.          3.        ]
   [ 1.65880881  2.          4.        ]
   [ 2.21427178  2.          5.        ]
   [ 2.12770111  2.          6.        ]
   [ 0.59811712  2.          7.        ]
   [ 2.15373458  2.          8.        ]
   [ 2.47151944  2.          9.        ]
   [ 2.78849347  3.          4.        ]
   [ 3.29699194  3.          5.        ]
   [ 2.90479808  3.          6.        ]
   [ 1.6405647   3.          7.        ]
   [ 3.2628552   3.          8.        ]
   [ 3.24135083  3.          9.        ]
   [ 0.59483003  4.          5.        ]
   [ 2.55441835  4.          6.        ]
   [ 1.22876339  4.          7.        ]
   [ 1.62616729  4.          8.        ]
   [ 2.7776452   4.          9.        ]
   [ 3.07635954  5.          6.        ]
   [ 1.7483827   5.          7.        ]
   [ 1.993107    5.          8.        ]
   [ 3.26526698  5.          9.        ]
   [ 2.34443787  6.          7.        ]
   [ 1.59405468  6.          8.        ]
   [ 0.46781919  6.          9.        ]
   [ 1.92762241  7.          8.        ]
   [ 2.69818642  7.          9.        ]
   [ 1.85007201  8.          9.        ]]
  </code></pre>
  
  <p>I have tried using </p>
  
  <pre><code>print all_data[np.argmax(all_data[:, 0]), 1]
  </code></pre>
  
  <p>but it returns the lowest value for the whole column not only for node 0 which I want. How to get the minimum associated with only node '0'? Also the argmin value seems to be rounded up! Any idea how to solve these problems? By the way I'm using numpy array.</p>