EdgeView comparison only checks edge ID, not contents

[leotrs]

This is Bad.

In [11]: H1 = xgi.Hypergraph([{0, 1, 2}, {0}, {1, 2}])

In [12]: H2 = xgi.Hypergraph([{1, 2, 3}, {0}, {1, 3}])

In [13]: H1 == H2
Out[13]: False

In [14]: H1.edges == H2.edges
Out[14]: True

[leotrs]

OK to be honest, what I wrote in the title is my current hunch as to why this is happening, but I might be wrong.

[leotrs]

An easy (temporary?) fix is to encourage the user to do this instead:

H1.edges.members(dtype=dict) == H2.edges.members(dtype=dict)

[maximelucas]

Is this a bug though? H.edges contains edges IDs, so your example is not so surprising. Although a user might write

In [14]: H1.edges == H2.edges

and expect

Out[14]: False

assuming it's gonna compare edges members rather than IDs.

We could implement = between H.edges as checking for the full dict {ID: members} as the fix you suggested. In both cases, we should clarify this in the doc.

[leotrs]

Yeah coming back to this the main problem I see is that the user may inadvertently compare two views from two different network instead of two views from the same network. And the question is whether we want EdgeViews to compare only based on the IDs rather than also take into account which network those IDs belong to.

[leotrs]

Okay I think my preference would be that comparing two views only works when they come from the same network. If the user wants to compare only the IDs contained, they can use view.ids. So we'd have:

H1.edges == H2.edges
# -> always False, regardless of edge IDs

H1.edges.ids == H2.edges.ids
# -> may be True, if H1 and H2 have the same edge IDs

[leotrs]

Will work on this after #406 is merged.

[maximelucas]

What do we want if the two have the same hyperedges (based on members) but different IDs?

[leotrs]

That sounds dangerously close to determining whether two hypergraphs are isomorphic :grin: