Confusing behavior when XG is created from a Graph with Paths missing rank information

[jeizenga]

If you build an XG from an existing Graph whose Paths are missing rank information, the Path information gets silently discarded. Or rather, the first traversal is preserved and all others are discarded. I tracked it down to a filtering step at https://github.com/vgteam/xg/blob/master/src/xg.cpp#L496, which seems to be designed to remove duplicates. Is this necessary? When do we expect to see Paths with duplicated ranks, and why is the correct response to arbitrarily discard one of them? It seems to me it would be better to raise an error or something.

[ekg]

We should at least raise an error.

…

On Wed, Mar 8, 2017, 9:58 PM Jordan Eizenga ***@***.***> wrote: If you build an XG from an existing Graph whose Paths are missing rank information, the Path information gets silently discarded. I tracked it down to a filtering step at https://github.com/vgteam/xg/blob/master/src/xg.cpp#L496, which seems to be designed to remove duplicates. Is this necessary? When do we expect to see Paths with duplicated ranks, and why is the correct response to arbitrarily discard one of them? It seems to me it would be better to raise an error or something. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <https://github.com/vgteam/xg/issues/55>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAI4EZ4i3kF-zcRdSftP2EWkjpMfcc-Tks5rjxZogaJpZM4MXTPa> .

[jeizenga]

Okay, I'll package that up with the PR for the algorithm I'm writing.