Re: [graphviz-interest] How to add and get custom attributes from dot-file?

2013/9/2, Emden R. Gansner <[email protected]>:
> On 9/2/13 5:54 AM, Igor Chetverovod wrote:
>> Hi all!
>> I am using  cgraph  for loading and parsing of a graph description
>> from a dot-file.
>> Now I need to add a custom  attributes to the nodes in the file and
>> have access to them after the  file reading to the memory. How can I
>> do that?
>>
>>
> Suppose you want nodes to carry the attribute "date". In your file, you
> would simply add
> another attribute a node:
>
>    node0 [color=red date="2 September 2013"]
>
> When you read the graph in, if np is a pointer (Agnode_t*) to node0,
> then you can just
> call agget(np, "date") and this will return the value of date stored in
> the node.
>
> Note that if no node has a date attribute, agget() will return NULL.
> Otherwise, it will return
> some non-NULL string value, either the value set to a specific node or
> the default date value,
> which well may be the empty string.
>
> If you want to add the attributes in your program, you first need to
> declare the attribute using
> agattr(). For example, you might do
>
>      s = agattr(g, AGNODE, "date", "");
>
> where g is a pointer to a graph and the last value specifies that the
> default date is the empty string"".
> After this, you can attach data values to nodes using
>
>      agset (np, "data", "1 January 2014");
>
> or, more efficiently,
>
>      agxset (np, s, "1 January 2014");
>
> Sometimes it is simpler to use
>
>      agsafeset (np, "data", "1 January 2014", "");
>
> which combines the attribute declaration and assignment.
>
>        Emden
>
>

Emdem, thank you.  This is what I need.

Best regards,
Igor
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