title: Remove duplicate columns in a list of dataframes r
body: <p>I have a List with many dataframes. Each dataframe contains duplicate columns. I would like to return only the unique columns in each dataframe.  I have tried several codes including below, but continue to get errors.  The code I'm presently using is below and a description of the first dataframe in my List is listed as well. I appreciate any help.</p>
  
  <pre><code>x  &lt;- lapply(dataFiles, function(x){
    for(i in 1:length(colnames(dataFiles)))
    dataFiles[[!duplicated(dataFiles[[i]])]]
  }
  )
  
  
  
  str(dataFiles[[1]])
  'data.frame':   20381 obs. of  10 variables:
   $ FILEID    : chr  "ACSSF" "ACSSF" "ACSSF" "ACSSF" ...
   $ FILETYPE  : num  2.01e+08 2.01e+08 2.01e+08 2.01e+08 2.01e+08 ...
   $ STUSAB    : chr  "ny" "ny" "ny" "ny" ...
   $ CHARITER  : int  0 0 0 0 0 0 0 0 0 0 ...
   $ SEQUENCE  : int  1 1 1 1 1 1 1 1 1 1 ...
   $ LOGRECNO  : int  3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 ...
   $ B00001_001: int  212 215 278 246 235 NA 225 522 213 262 ...
   $ B00002_001: int  108 124 126 105 122 NA 108 105 104 140 ...
   $ LOGRECNO  : int  3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 ...
   $ GEOID     : chr  "14000US36001000100" "14000US36001000200" "14000US36001000300" "14000US36001000401" ...
  </code></pre>