title: Top N columns in a data frame with their corresponding column names and row names
body: <p>I have a data frame which depicts similarity between users by a numeric number. A representative dataset is as mentioned below:</p>
  
  <pre><code>    C1  C2  C3  C4  C5  C6  C7  C8  C9 C10
  R1  72  71  9   47  77  58  74  52  19  82
  R2  43  25  75  100 66  97  71  76  26  57
  R3  1   32  87  81  88  66  84  29  15  49
  R4  66  68  22  63  40  53  32  69  57  58
  R5  42  34  30  77  36  41  61  68  61  35
  R6  59  23  38  3   20  86  72  81  58  1
  R7  40  86  45  21  44  63  79  77  35  47
  R8  15  75  15  19  34  72  96  28  24  38
  R9  13  69  2   30  81  72  38  95  92  10
  R10 69  26  23  100 55  10  29  16  20  38
  </code></pre>
  
  <p>I want the <strong>top N</strong> (for eg 7) columns of each row along with the column name and the corresponding row name. So it can be another <code>dataframe</code> as mentioned below. Either it can be in a single step or multiple steps with intermediaries data frames formed to arrive at this solution. </p>
  
  <pre><code>col1 col2 col3
  R1  C10 82
  R1  C5  77
  R1  C7  74
  R1  C1  72
  R1  C2  71
  R1  C6  58
  R1  C8  52
  R2  C4  100
  R2  C6  97
  R2  C8  76
  R2  C3  75
  R2  C7  71
  R2  C5  66
  R2  C10 57
  </code></pre>