[igraph] adding rownames in line.graph

[Ravindran, Kiron]

I have a dataset of firms contracting with each other. I am trying to
study the proliferation of contract design characteristics along this
network. In order to do this I have first converted my two-mode
adjacency matrix into a lingraph. Each node in the linegraph now is a
contract with various contract attributes.

What I am trying to do is to create a variable that is the count of
all the alters that match the ego in terms of a particular contract
trait. This is basically a row or column total in the linegraph
recoded to take the value of 1 or 0 if the contract traits match.

Now since my dataset is a set of cross-sections taken every year, I
should also make sure that this count only includes alters that have
had this trait in the past and not in the future. So the long way is
to do this process year by year and then create a unique variable for each year

So far I have managed the following

import the edgelist from stata
make it a linegraph
The next step is to multiply every element of  row i with a vector
(N*1) with the contract attribute then
do a row sum and save that rowsum saved as another vector which i will
export to stata.

The catch is i am not sure the row order in the linegraph is the same
as that in the edgelist. And with 20,000 observations it's hard to
check manually. So i'd like to append the linegraph with a rowlabel
comprising of "vertex1-vertex2" from the edgelist. Am sure there is a
simple way to do this but am not able to figure it out

Thanks in advance

Kiron