//rdatatable.gitlab.io/data.table/reference/as.data.table.html" class="external-link">as.data.table</a></code>, <code><a href="https://rdatatable.gitlab.io/data.table/reference/J.html" class="external-link">CJ</a></code>, <code><a href="https://rdatatable.gitlab.io/data.table/reference/copy.html" class="external-link">copy</a></code>, <code><a href="https://rdatatable.gitlab.io/data.table/reference/data.table.html" class="external-link">data.table</a></code>, <code>fcoalesce</code>, <code><a href="https://r