Graphviz/ Table/ How to merge cells - cell

Question

I would like to draw a graph like this -
I have Graphviz code like this -
digraph G {
"test" [
label = <<table border="0" cellspacing="0">
<tr>
<td port="f0" border="1" bgcolor="darkorange">TEST</td>
<td port="f1" border="1" bgcolor="darkorange"></td>
</tr>
<tr>
<td port="f2" border="1" bgcolor="cyan">A</td>
<td>
<table border="0" cellspacing="0">
<tr><td port="f3" border="1" bgcolor="azure">A1</td></tr>
<tr><td port="f4" border="1" bgcolor="azure">A2</td></tr>
<tr><td port="f5" border="1" bgcolor="azure">A3</td></tr>
</table>
</td>
</tr>
<tr>
<td port="f5" border="1" bgcolor="gray">Else</td>
<td port="f6" border="1" bgcolor="gray"></td>
</tr>
</table>>
shape = "none"
];
}
But it gives the graph like this
Would you please suggest how can we tweak the code to achieve the objective - merging f0, f1 on top and f5,f6 at bottom?

Answer 1

You can use HTML <td>s with colspan and rowspan attributes in GraphViz. These allow one cell to span multiple columns and/or rows inside a table.
This also simplifies your digraph, as only one table is needed.
digraph G {
"test" [
label = <<table border="0" cellspacing="0">
<tr>
<td colspan="2" port="f0" border="1" bgcolor="darkorange">TEST</td>
</tr>
<tr>
<td rowspan="3" port="f5" border="1" bgcolor="blue">A</td>
<td port="f6" border="1" bgcolor="white">A1</td>
</tr>
<tr>
<td port="f6" border="1" bgcolor="white">A2</td>
</tr>
<tr>
<td port="f6" border="1" bgcolor="white">A3</td>
</tr>
<tr>
<td colspan="2" port="f0" border="1" bgcolor="grey">Else</td>
</tr>
</table>>
shape = "none"
];
}
This gives you the following basic output, which you can then customize for spacing, line colors, etc:

Answer 2

This one also works. what's is the difference?
digraph G {
"test" [
label = <<table border="0" cellspacing="0">
<tr><td colspan="2" port="f0" border="1" bgcolor="darkorange">TEST</td> </tr>
<tr><td rowspan="4" port="f5" border="1" bgcolor="blue">A</td></tr>
<tr><td port="f6" border="1" bgcolor="white">A1</td></tr>
<tr><td port="f6" border="1" bgcolor="white">A2</td></tr>
<tr><td port="f6" border="1" bgcolor="white">A3</td></tr>
<tr><td colspan="2" port="f0" border="1" bgcolor="grey">Else</td></tr>
</table>>
shape = "none"
];
}