title: R: Join/merge list of data frames by common columns and appending
body: <p>I am looking for a way to merge a (long) list of data frames into a data frame, by keeping common columns and appending a column that contains values different in each data frame.</p>
  
  <pre><code>head(dflist[['sampleA']])
  seqnames   start     end width strand           gene reads
  1     chr1   30366   30503   138      + hsa-mir-1302-2     7
  2     chr1 1102484 1102578    95      +   hsa-mir-200b  2158
  3     chr1 1103243 1103332    90      +   hsa-mir-200a 12939
  4     chr1 1104385 1104467    83      +    hsa-mir-429  2775
  5     chr1 3044539 3044599    61      +   hsa-mir-4251     0
  6     chr1 3477259 3477354    96      -   hsa-mir-551a   464
  
  head(dflist[['sampleB']])
    seqnames   start     end width strand           gene reads
  1     chr1   30366   30503   138      + hsa-mir-1302-2     6
  2     chr1 1102484 1102578    95      +   hsa-mir-200b  1407
  3     chr1 1103243 1103332    90      +   hsa-mir-200a  8874
  4     chr1 1104385 1104467    83      +    hsa-mir-429  1721
  5     chr1 3044539 3044599    61      +   hsa-mir-4251     0
  6     chr1 3477259 3477354    96      -   hsa-mir-551a   349
  </code></pre>
  
  <p>what I look for is an output like that:</p>
  
  <pre><code> seqnames   start     end width strand           gene reads.sampleA
  1     chr1   30366   30503   138      + hsa-mir-1302-2     7
  2     chr1 1102484 1102578    95      +   hsa-mir-200b  2158
  3     chr1 1103243 1103332    90      +   hsa-mir-200a 12939
  4     chr1 1104385 1104467    83      +    hsa-mir-429  2775
  5     chr1 3044539 3044599    61      +   hsa-mir-4251     0
  6     chr1 3477259 3477354    96      -   hsa-mir-551a   464
  reads.sampleB
  1                                      6
  2                                   1407
  3                                   8874
  4                                   1721
  5                                      0
  6                                    349
  </code></pre>
  
  <p>I'm pretty sure this is a rather simple and common task, but I can't find/google a way to do it. </p>