[igraph] Warnings

[Herb Roseman]

Hi:

You are correct about the extra function I used.  I got the idea from Python documentation.

I tested get_shortest_path in my little program and it seems that it is doing what it should once the warnings are suppressed.  For an invalid path it returns an empty list for a self-referential path it returns the index of the vertex.( In your example A is the zeroth vertex.) This allows the user  to easily process the results.  What confused me was that the same warning is returned for both cases.

Your solution is a bit smoother than what is currently available.  But in any case the user would have to discover it unless it is documented.  That's been my problem.

Sorry about tkplot.  I may be forced to convert my graphs to R.  Those seventeenth century philosophers knew nothing about computer graphics. The logic of Part II of his Ethics may be too detailed to plot on a single page.  I'll soon find out.

Best.