Setting Edge Gradient

graph-tool
1

Hello,

Say I have an edge property (of type double) with values ranging from 0.0 to
1.0. I want this value to be set as the alpha for my edges or at least be
used as the offset with the gradient option in the graph_draw function. The
idea is that for edges with stronger weights, I can reduce the alpha.
(Edges weighted at 0.0 will disappear.) How can I make that happen?

Using graph_draw(..., gradient=[values, 0, 0, 0, 1.0]) will not work, as the
0th index in the gradient option list must be a value from 0.0-1.0, and not
some set or list or properties. There's got to be a way to do this, though.
It's simple enough; I'm probably just missing something.

Thanks,
-John

2

You can access the properties as 2d arrays as follows

    a = zeros((5, g.num_edges()))
    a[0] = values

    gradients = g.new_vertex_property("vector<double>")
    gradients.set_2d_array(a)

    graph_draw(g, gradients=gradients)

Best,
Tiago