The W builder warns on init if there are multiple components and islands present. This can be silenced by a keyword but it enabled by default. On Graph, we have nothing like this and we needs to check this ourselves.

I was debugging a weird failure of esda.Join_Counts_Local and realised it is caused by multiple components only when I tried passing the graph as W, at which point I got the warning and immediately understood the issue.

I am wondering whether we should do something about this on Graph as well. One option is to mimic the behaviour of W with the warning, other less intrusive option might be to expand the __repr__ to include this information (as Graph.summary() does). I sort of came to a conclusion yesterday that it might be useful to avoid unforeseen issues.