title: Using ggplot function in R error : could not find function ggplot
body: <p>I have installed ggplot and ggplot2 and their dependencies, but I cannot use the function <code>ggplot</code>; whenever I try to use it I get</p>
  <blockquote>
  <p>Error in ggplot ... could not find function &quot;ggplot&quot;</p>
  </blockquote>