I’m a newbe in this (although programmer in other areas since a long time).
I have a working graph (excel plus scripts) where I try to increase fontsize of the text within the nodes (I think they are called that?).
It seems to me that this is controlled by the SubGraph function, but there is no specific description of the syntax of the SubGraph function in the doc on your home page.
Anyway:
What is the syntax for the subGraph function in the script?
How to I bind the subGraph function to a specific node/data/text?
How is the syntax for setting the fontsize?
I have tried a bit with changes in the script, but only succeeded to change the color and thickness of the outline of the node.
TIA
Thomas Berg
Note that the graph/excel is not created by me.
Unfortunately I can’t ask the author, he has left the company.
What do you mean by “can’t see the script”? I can post the script, eighter by the screenshots like the one above or by uploading the script as a text file.
But I don’t quite understand the relevance to my initial question that was about the Graphviz code/function in general.
While it is possible to set fontsize for sets of nodes, the easiest way is probably to add the fontsize string to each node definition/declaration. There is even an example of adding fontsize=20 on one of the screenshots.
Does this help?
I have tried with different settings of fontsize (by changing the existing ones) but with no result whatsoever.
As you may understand I have difficulty understanding the structure of the script as such and the full format of the subgraph function. By some reason it is missing from the homepage although other elements is described there.
I am also unsure about which parts is pure VB and which that are Graphviz specific functions. (Possible loaded from the Graphviz load library?)
I have succeded to change the color and thickness of the ellipsoid borders of the nodes. But evidently not the fontsize.
Do you want the script or maybe the resulting graph?
Yes there are examples. Excel to Graphviz is an Excel spreadsheet containing VBA code to generate Graphviz graphs. It acts like a multi-tab IDE for Graphviz.
The Overview page contains many pictures of the features.
The controls for each worksheet are provided in the Excel ribbon tab.
Each control has tooltips which explain their function when you hover the mouse over them.
Each ribbon tab has a Help button which will bring you to the appropriate page on the web site.
One of the worksheets shows the Graphviz source being generated. You can learn much about the dot language by clicking options and observing the effect.
Maybe increase mincross passes using mclimit=2 in the hope of eliminating some of the worst edge crossings in the above. Sorry, I’m not sure why we have that problem.
I pasted your question into Grok. Here is how it answered.
In Graphviz, the subgraph construct is a native element of the DOT language, which is the graph description language used by Graphviz. It is not an external or non-native function that wraps other code—it’s built directly into the core functionality of Graphviz.
Details:
A subgraph in Graphviz is used to group nodes and edges together within a larger graph. It’s a fundamental part of the DOT syntax and is natively supported by the Graphviz rendering engine.
Subgraphs can be used for various purposes, such as defining clusters (when prefixed with cluster_ and styled appropriately) or simply organizing parts of a graph without visual clustering.
The Graphviz source code (written primarily in C) handles subgraphs as part of its internal graph representation and layout algorithms. There’s no external wrapper involved; it’s baked into the system.
For example, in DOT:
dot
digraph G {
subgraph cluster_0 {
a -> b;
label = "Cluster 0";
}
subgraph cluster_1 {
c -> d;
label = "Cluster 1";
}
}
Here, subgraph is a native keyword recognized by Graphviz to structure the graph.
If you’re curious about the implementation, the Graphviz codebase (available on platforms like GitLab) parses subgraph directly in its grammar (via tools like bison and flex for the DOT parser), confirming its status as a core feature. No external libraries or wrappers are required for it to function.
Yes, but I haven’t found a specific description of the subgraph element,
There a lot of examples and references to subgraph but not the element itself. There are description for some specific usages of the subgraph, like “Whether the subgraph is a cluster” etc. But as I got (formal?) error messages when trying to add/change options to the subgraph it would help to see a complete format diagram för subgraph.
E g I have problem understanding what happens when using constructs like
subGraph = CStr(Worksheets(“OPC”).Cells(row, 1)) + “fontsize=20”
Where a complete format description would help, at least I think so.
In this construct subGraph is merely a string. The CStr function converts the value in the first column of a row of worksheet OPC to a string. “fontsize=20” is then appended to it, and the resulting string is assigned to string variable subGraph. I’m assuming row is being supplied as a loop counter.
The fix may be as simple as adding a space before fontsize, i.e. ” fontsize=20” as I sense the lack of a space is causing invalid syntax once appended to the cell value.
I am well-versed in VBA. Please feel free to message me directly and I will try to provide assistance.
Graphviz doesn’t have a notion of “elements”, unless you mean elements of the rendered image, e.g. SVG elements. In that sense nodes, edges and clusters are elements, but not subgraphs.
Unless a subgraph is a cluster, it doesn’t exist independently. It’s just a convenient way of grouping nodes and edges together. See DOT Language | Graphviz.
Excel to Graphviz is not part of Graphviz. I guess you are asking for subgraph elements in Excel to Graphviz, not in Graphviz itself and that you were asking for a complete manual for Excel to Graphviz. If so, I hope that Jeff’s answers has helped you.
To clear up some confusion, the VBA code snippet is from a VBA module in Thomas’ spreadsheet, not from Excel to Graphviz. In it, subGraph is a string variable.
Excel to Graphviz entered the conversation because the question was asked if there are other examples where VBA is used in Excel to run Graphviz. I provided it as an example.
It also has a PDF manual which explains some of the Graphviz terminology and concepts in its introductory sections. I thought these materials would complement the PDF manual by Gansner, North, and Koutsofios.
