[igraph] prunning vertices

[Ahmed Abdeen Hamed]

Good morning,

I need to prune vertices in a graph based on a certain criteria (not in a given list). When doing so, this leaves isolated vertices, which I also like to remove. But when doing do, delete_vertices() does not remove all vertices with degree == 0. I am not sure why this is happening. 

I am attaching the script and the data that I am using so you can see the issue.

Thanks very much,

-Ahmed

sample-of-all.csv
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delete-isolated-hashtags.py
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good-hashtags.csv
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