Is there a way to alter the edge opacity in Python igraph?
Edge opacity can be altered with the color attribute of the edge or with the edge_color keyword argument of plot(). The colors that you specify there are passed through the color_name_to_rgba function so you can use anything that color_name_to_rgba understands there; the easiest is probably an (R, G, B, A) tuple or the standard HTML #rrggbbaa syntax, where A is the opacity. Unfortunately this is not documented well but I'll fix it in the next release.
I know that you can adjust a graphs overall opacity in the plot function (opacity = (0 to 1)), but I cannot find anything in the manual or online searches that speak of altering the edge opacity (or transparency)?