Compute the projection of a graph, provided as an
`igraph`

object, on the grid of the `somRes`

object.

`projectIGraph(object, init.graph, ...)`

- object
a

`somRes`

object.- init.graph
an igraph whose number of vertices is equal to the clustering length of the

`somRes`

object.- ...
Not used.

The result is an `igraph`

which vertexes are the
clusters (the clustering is thus understood as a vertex clustering) and the
edges are the counts of edges in the original graph between two vertices
corresponding to the two clusters in the projected graph or, if
`init.graph`

is a weighted graph, the sum of the weights between the
pairs of vertices corresponding to the two clusters.

The resulting igraph object's attributes are:

the graph attribute

`layout`

which provides the layout of the projected graph according to the grid of the SOM;the vertex attributes

`name`

and`size`

which, respectively are the vertex number on the grid and the number of vertexes included in the corresponding cluster;the edge attribute

`weight`

which gives the number of edges (or the sum of the weights) between the vertexes of the two corresponding clusters.

Olteanu M., Villa-Vialaneix N. (2015) Using SOMbrero for clustering and
visualizing graphs. *Journal de la Société Française de Statistique*,
**156**, 95-119.

`projectIGraph.somSC`

which uses the results of a
super-clustering to obtain another projected graph. `plot.somRes`

with the option `type="graph"`

or `plot.somSC`

with the
option `type="projgraph"`

.