[igraph] cohesive.blocks: exporting blocks as a data frame

[joe j]

Dear all,

Using igraph version .6 in R 2.12.2, I am trying to calculate cohesive
blocks for each year over a period of time. For later analysis I need
a matrix (that's a data frame which can be exported, for example as a
csv or dta file) with the following minimum information: vertex name,
block code (to identify the block), and hierarchy level. This way, I
hope, among other things, to keep track of the pattern of block
membership of each vertex over time. Knowledge of hierarchy level
would enable me to combine several blocks in order to have smaller
number of blocks. Would this be possible? I tried exporting the data
to pajek, but couldn't figure out a way to extract the information I
needed. Any suggestion would be appropriated.

A related point. I started off by looking into Lambda Sets a la
Borgatti et al ( LS sets, lambda sets and other cohesive subsets. By
S. P. Borgatti, M. G. Everett, P. R. Shirey, Social Networks 12 (1990)
p. 337-357 ), but learned the superiority of cohesive blocking from
its Wiki page. However, I also found a remark in there that: "there is
a difference between the Peter McMahan's strict structural cohesion
algorithm and the Moody-White cohesive embedding algorithm". Has this
been fixed in igraph .6?

Finally, I assume that cohesive blocking doesn't yet accommodate
weights, but please let me know if this is not the case.

Best regards,
Joe