s://rdrr.io/r/base/make.names.html" class="external-link">make.names()</a></code> should be
used to force names of the returned data frame to by syntactically valid.</p></dd>


<dt>na.action</dt>
<dd><p>A function (or character string naming a function) that determines how NAs are treated.
Options include <code>"na.warn"</code> which removes missing data and emits a warning,
<code>"na.pass"</code> which includes all of the data,
<code>"na.omit"</code> or <code>"na.exclude"</code> which silently discard miss