title: Undefined Columns Selected Error in data.frame
body: <p>Using the <strong>recommenderlab</strong> package on RStudio. Read the table from a .csv file and named the data.frame <code>Sweets</code>. Getting an error when using the <code>Recommender</code> command:</p>
  
  <pre><code>Sweets &lt;- read.table(file.choose(), header = FALSE,sep=",", nrows = 17903)
  
  &gt; recommenderRegistry$get_entries(dataType = "realRatingMatrix")
  $IBCF_realRatingMatrix
  Recommender method: IBCF
  Description: Recommender based on item-based collaborative filtering (real data).
  
  &gt; Recommender(Sweets[1:17903], method="IBCF")
  Error in Recommender(Sweets[1:17903], method = "IBCF") : 
  error in evaluating the argument 'data' in selecting a method for function 'Recommender':           
  Error in `[.data.frame`(Sweets, 1:17903) : undefined columns selected
  </code></pre>
  
  <p>About Data:</p>
  
  <pre><code>ncol(Sweets)
  [1] 3
  
  nrow(Sweets)
  [1] 17903
  
  str(Sweets)
  'data.frame':   17903 obs. of  3 variables:
  $ V1: int  351 57 385 286 126 371 131 116 364 180 ...
  $ V2: int  31 9 30 23 16 46 20 17 18 40 ...
  $ V3: int  0 3 1 4 3 0 5 3 3 2 ...
  
  head(Sweets)[, 1:3]
  V1 V2 V3
  1 351 31  0
  2  57  9  3
  3 385 30  1
  4 286 23  4
  5 126 16  3
  6 371 46  0
  </code></pre>
  
  <p>Please let me know if I can provide more information. </p>