rmat to plot it with <strong>ggplot2</strong>. The preparation of the data—e.g. converting data types and setting factor levels, aggregating values, estimating data summaries, reshaping the data set or combining it with another source—is called <em>data wrangling</em>, <em>data munging</em>, or <strong>data manipulation</strong>.</p>
<p>To explore and retrieve summary estimates of individual variables, the following functions are useful:</p>
<ul>
<li><code>min()</code>, <code>max()</code>, <code>range(