title: How can I order a dataframe by the second column in R?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1296646/how-to-sort-a-dataframe-by-columns-in-r">How to sort a dataframe by column(s) in R</a>  </p>
  </blockquote>
  
  
  
  <p>I was just wondering if some one could help me out, I have what I thought should be a easy problem to solve.</p>
  
  <p>I have the table below:</p>
  
  <pre><code>SampleID           Cluster
  
  R0132F041p          1
  
  R0132F127           1
  
  R0132F064           1
  
  R0132F068p          1
  
  R0132F015           2
  
  R0132F094           3
  
  R0132F105           1
  
  R0132F013           2
  
  R0132F114           1
  
  R0132F014           2
  
  R0132F039p          3
  
  R0132F137           1
  
  R0132F059           1
  
  R0132F138p          2
  
  R0132F038p          2
  </code></pre>
  
  <p>and I would like to sort/order it by <strong>Cluster</strong> to get the results as below:</p>
  
  <pre><code>SampleID    Cluster
  
  R0132F041p  1
  
  R0132F127   1
  
  R0132F064   1
  
  R0132F068p  1
  
  R0132F105   1
  
  R0132F114   1
  
  R0132F137   1
  
  R0132F059   1
  
  R0132F015   2
  
  R0132F013   2
  
  R0132F014   2
  
  R0132F138p  2
  
  R0132F038p  2
  
  R0132F094   3
  
  R0132F039p  3
  </code></pre>
  
  <p>I have tried the following R code: </p>
  
  <pre><code>data&lt;-read.table('Table.txt', header=TRUE,row.names=1,sep='\t')
  
  data &lt;- data.frame(data)
  data &lt;- data[order(data$Cluster),]
  write.table(data, file = 'OrderedTable.txt', append = TRUE,quote=FALSE, sep = '\t', na ='NA', dec = '.', row.names = TRUE, col.names = FALSE)
  </code></pre>
  
  <p>and get the following output:</p>
  
  <pre><code>1   1
  
  2   1
  
  3   1
  
  4   1
  
  5   1
  
  6   1
  
  7   1
  
  8   1
  
  9   2
  
  10  2
  
  11  2
  
  12  2
  
  13  2
  
  14  3
  
  15  3
  </code></pre>
  
  <p>Why have the <strong>SampleIDs</strong> been replaced by the numbers 1-15 and what do these numbers represent, I have read the <code>?order()</code> page however this seems to explain <strong>sort.list</strong> better than <strong>order()</strong> if any one could help me out on this I would be very grateful.</p>