title: convert the value in 1st column into row names
body: <p>I'd like to the convert the values in the first column into row names.<br></p>
  
  <p>There are some similar questions about it like this<br>
  <a href="https://stackoverflow.com/questions/5555408/convert-the-values-in-a-column-into-row-names-in-an-existing-data-frame-in-r">Convert the values in a column into row names in an existing data frame in R</a></p>
  
  <p>However, the thing is that I would like to do that in the files with listed up.<br>
  What should I do to apply into multiple files (ex. <code>int_file[[i]]</code>)?</p>
  
  <pre><code>&gt; exp = list.files(pattern=glob2rx("*_input_*.txt"))
  &gt; int_file = lapply(exp, read.table, sep="\t", header = T)
  
  # I tried with int_files=lapply(exp, red.table. sep="\t", row.names=NULL)
  
  &gt; exp
  [1] "1_input_1.txt" "2_input_2.txt"
  &gt; dim(int_file[[1])
  [1] 2000 20
  &gt; dim(int_file[[2]])
  [1] 3000 20
  
  &gt; type(int_file[[1]][1,1])
  [1] "factor"
  </code></pre>