title: R file won't knit, saying readxl package doesn't exist
body: <p>I'm using RStudio, and trying to knit my file to hand in my assignment. I installed the package "readxl" to read in a couple of excel files, and it worked fine in the actual coding of the assignment. But when I go to knit the file, I keep getting the error:</p>
  
  <pre><code>Error in library(readxl) : there is no package called 'readxl'
  Calls: &lt;Anonymous&gt; ... withCallingHandlers -&gt; withVisible -&gt; eval -&gt; eval -&gt; 
  library
  Execution halted
  </code></pre>
  
  <p>This is the code in question:</p>
  
  <pre><code>install.packages("tidyverse",repos = "http://cran.us.r-project.org")
  library(tidyverse)
  install.packages("readxl",repos = "http://cran.us.r-project.org")
  library(readxl)
  </code></pre>
  
  <p>This has been frustrating me for over an hour and I just can't fix it. I can see the readxl package to the right of the console, in the "packages" tab. Any help will be much appreciated</p>