Changes

<h1><span style="font-family:courier new,courier,monospace">Convert a molten data table into an data table (array type)</span></h1>

<div style="background:#eee;border:1px solid #ccc;padding:5px 10px;"><span style="font-family:courier new,courier,monospace"><span style="font-size:11px">&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Species &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ID &nbsp; &nbsp; &nbsp; Var1 Var2 &nbsp; &nbsp; &nbsp; &nbsp; Val &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Group &nbsp; &nbsp; &nbsp;Print_name<br />

<h1><span style="font-family:courier new,courier,monospace">Data table aggregation with &#39;by&#39;</span></h1>

<div style="background:#eee;border:1px solid #ccc;padding:5px 10px;"><span style="font-family:courier new,courier,monospace"><span style="font-size:11px">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;ID CDS_length &nbsp; &nbsp; &nbsp;FPKM &nbsp; ord bin<br />

&nbsp; &nbsp; 5: g10012.t1.cds@g10012@000073F &nbsp;10.762382 0.5596289 &nbsp; 785 &nbsp; 1</span></span></div>

<div style="background:#eee;border:1px solid #ccc;padding:5px 10px;"><span style="font-family:courier new,courier,monospace"><big>dt[, .(Mean_CDS_length = mean(CDS_length), Mean_FPKM = mean(FPKM)), by=bin]</big></span></div>

<div style="background:#eee;border:1px solid #ccc;padding:5px 10px;"><span style="font-family:courier new,courier,monospace"><span style="font-size:11px">&nbsp; &nbsp; bin Mean_CDS_length Mean_FPKM<br />