Problem with closeness centrality

Dec 5, 2013 at 2:10 AM
I have a data set that consists of web API's and mashups
When computing the closeness centrality most of the values seems to be zero when cross checked the data set,these nodes seem to have only one or two vertices or they may jst be a self loop
for example
and b is not connected to any other vertex other than a
or the other case would be
b has two connections a and c and a and c may have any number of connections
In both the cases b has a closeness of 0 i'm confused if this is right!!
Can somebody help me with an explanation

Thank you
Dec 6, 2013 at 5:11 AM
I would expect the closeness centrality to be zero only for vertices that have no connections to other vertices. If you see a closeness centrality of "0.000" in a cell where you expect a non-zero value, it's probably due to rounding errors. For example, in one of my graphs I see a closeness centrality of "0.000" for a vertex that is connected to one other vertex, but the Excel formula bar shows "0.000242" for that cell. If I reformat the cell to show six decimal places instead of the standard three, the cell changes from "0.000" to "0.000242".

-- Tony