title: Writing output of a for loop to pandas data-frame
body: <p>How can I write an output of a for loop to pandas data-frame?</p>
  
  <p>Input data is a list of data-frames (df_elements).</p>
  
  <pre><code>[                          seq  score    status
  1652  TGGCTTCGATTTTGTTATCGATG  -0.22  negative
  1277  GTACTGTGGAATCTCGGCAGGCT   4.87  negative
  302   CCAAAGTCTCACTTGTTGAGAAC  -4.66  negative
  1756  TGGCGGTGGTGGCGGCGCAGAGC   1.55  negative
  5043  TGACGAAACATCTTATAAAGGAA   1.96  negative
  3859  CAGAGCTCTTCAAACTTAAGAAC  -0.39  negative
  1937  GTATGCTTGTGCTTCTCCAAAAA  -0.91  negative
  2805  GGCCGGCCTGTGGTCGACGGGGA  -3.26  negative
  3353                CCGATGGGC  -1.97  negative
  5352  ACTTACTATTTACTGATCAGCAC   3.53  negative
  5901  TTGAGGCTCTCCTTATCCAGATT   6.37  negative
  5790  AAGGAAACGTGTAATGATAGGCG  -2.69  negative,                           seq  score    status
  2197  CTTCCATTGAGCTGCTCCAGCAC  -0.97  negative
  1336  CCAAATGCAACAATTCAAAGCCC  -0.44  negative
  4825                CAATTTTGT  -6.44  negative
  4991  ATACTGTTTGCTCACAAAAGGAG   2.15  negative
  1652  TGGCTTCGATTTTGTTATCGATG  -0.22  negative
  1964  ACCACTTTGTGGACGAATACGAC  -4.51  negative
  4443  TTCCTCGTCTAGCCTTTCAGTGC   3.05  negative
  4208  TGGCTGTGAACCCCTATCAGCTG   2.70  negative
  212   CTGTCGTTTCAATGTTTAAGATA   6.43  negative
  775                 GCTTTAAGT   0.06  negative
  3899                GAGCAAAGC  -6.61  negative
  
  </code></pre>
  
  <p>I am trying to write the output of the below for loop to a data-frame. I tried by creating an empty list (data) and append row-wise output using data.append. I am getting an error like <strong>cannot concatenate object of type "";</strong></p>
  
  <p>The code is given below which print the output in the console:</p>
  
  <pre><code>
  cut_off = [0,1,2]
  
  for co in cut_off:
      for df in df_elements:
          print co, "\t", str((df['score'] &gt; co).sum())
  
  </code></pre>
  
  <p>The code should compare the cut_off value to the column score and print the total for each data-frame element, where the score is > than cut_off. </p>
  
  <p>The output should look like this:</p>
  
  <pre><code>cutoff number
  0   5  #for first dataframe element
  0   5  #for second dataframe element
  
  </code></pre>