title: could not find function "spread"
body: <p>So at the moment I am trying to figure out how to build a movie recommender system from MovieLense (<a href="https://grouplens.org/datasets/movielens/100k/" rel="nofollow noreferrer">https://grouplens.org/datasets/movielens/100k/</a>). I read some instructions from a tutorial.</p>
  
  <pre><code>library(dplyr)
  library(recommenderlab)
  library(magrittr)
  
  data &lt;- read.table("u.data", header = F, stringsAsFactors = T) 
  head(data)
  
     V1  V2 V3        V4
  1 196 242  3 881250949
  2 186 302  3 891717742
  3  22 377  1 878887116
  4 244  51  2 880606923
  5 166 346  1 886397596
  6 298 474  4 884182806
  </code></pre>
  
  <p>Explanation: <code>V1</code> is userid, <code>V2</code> is itemid, <code>V3</code> is rating </p>
  
  <p>Now I need to log format to ratingMatrix, and the result will be like this:</p>
  
  <pre><code>    1  2  3  4  5  6  7  8  9 10
  1   5  3  4  3  3  5  4  1  5  3
  2   4 NA NA NA NA NA NA NA NA  2
  3  NA NA NA NA NA NA NA NA NA NA
  4  NA NA NA NA NA NA NA NA NA NA
  5   4  3 NA NA NA NA NA NA NA NA
  6   4 NA NA NA NA NA  2  4  4 NA
  7  NA NA NA  5 NA NA  5  5  5  4
  8  NA NA NA NA NA NA  3 NA NA NA
  9  NA NA NA NA NA  5  4 NA NA NA
  10  4 NA NA  4 NA NA  4 NA  4 NA
  </code></pre>
  
  <p>code:</p>
  
  <pre><code>temp = data %&gt;% select(1:3) %&gt;% spread(V2,V3) %&gt;% select(-1)
  temp[1:10,1:10]
  </code></pre>
  
  <blockquote>
    <p>Error in spread(., V2, V3) : could not find function "spread"</p>
  </blockquote>