Boost Dynamic Properties with Custom get property

Question

I am trying to use boost::dynamic properties to multiple properties to the Graphviz output.

I am familiar with custom property writer (How to print a graph in graphviz with multiple properties displayed), but I am trying to do the same thing with dynamic properties. How do we write the above edge property writer using the dynamic properties in the following code? I want to write if else statements on the values of the weight and capacity as in if(weight <5 && capacity <5) then color = red and so on.

boost::dynamic_properties dp/*(ignore_other_properties)*/;
dp.property("node_id", get(&vert::name, g));
dp.property("color", get(??,g));
write_graphviz_dp(std::cout, g, dp);

Huh. What color do you want it to have? There is no mention of it in the linked answer. If anything, the trick would likely be exactly the same: `get(&edge::color, g)` (assuming that `edge` has a member named `color`) — sehe, Jul 19 '19 at 08:33
I have edited the question to mention that part. Edge has weight and capacity as its members and I want to use these two properties to write an if-else block to assign colors in the output graph. In the linked answer, I can do that in the operator() function but how do we that using the dp.property()? — chester cheetah, Jul 19 '19 at 16:37

score 1 · Accepted Answer · answered Jul 19 '19 at 20:33

See some options here: map set/get requests into C++ class/structure changes

You can either transform the result of one property map, or you can use a functional property map altogether.

Transforming values:

An example of using dynamic properties to transform a color property is here: Manually colouring of boost's graphs

Functional map:

How to use boost::graph dijkstra's algorithm if vertex properties are pointers?
My preference would be to use a member function and bind it using the transform_value_property_map as shown above, e.g. Using boost graph library with a custom class for vertices
But here is an example using function_property_map as well boost dijkstra_shortest_paths: can't extract (or find?) the path (path contains a cycle)

Note that you also have make_constant_property_map (e.g. Boost Dynamic Properties with Custom get property)

Thanks. This perfectly fits the case I was trying to solve. I was not aware of the make_transform_value_property_map. — chester cheetah, Jul 19 '19 at 20:54

Boost Dynamic Properties with Custom get property

1 Answers1

Transforming values:

Functional map:

Linked