I think the new packages from Hadley Wickham are beautiful and straight forward.<p><a href="https:&#x2F;&#x2F;cran.rstudio.com&#x2F;web&#x2F;packages&#x2F;dplyr&#x2F;vignettes&#x2F;introduction.html" rel="nofollow">https:&#x2F;&#x2F;cran.rstudio.com&#x2F;web&#x2F;packages&#x2F;dplyr&#x2F;vignettes&#x2F;introd...</a><p>End example from a airplane arrival and departure dataset:<p>flights %&gt;%<p><pre><code>  group_by(year, month, day) %&gt;%

  select(arr_delay, dep_delay) %&gt;%

  summarise(

    arr = mean(arr_delay, na.rm = TRUE),

    dep = mean(dep_delay, na.rm = TRUE)

  ) %&gt;%

  filter(arr &gt; 30 | dep &gt; 30)</code></pre>