# bipartite.projection

From igraph v0.5.3
by Gabor Csardi

##### Project a bipartite graph

A bipartite graph is projected into two one-mode networks

- Keywords
- graphs

##### Usage

```
bipartite.projection.size(graph, types=NULL)
bipartite.projection (graph, types=NULL, probe1=-1)
```

##### Arguments

- graph
- The input graph. It can be directed, but edge directions are ignored during the computation.
- types
- An optional vertex type vector to use instead of the
vertex attribute. You must supply this argument if the graph has no`type`

vertex attribute.`type`

- probe1
- This argument can be used to specify the order of the projections in the resulting list. If given and non-negative, then it is considered as a vertex id; the projection containing the first one in the result list.

##### Details

Bipartite graphs have a `type`

`FALSE`

for the vertices of the first
kind and `TRUE`

for vertices of the second kind.

`bipartite.projection.size`

calculates the number of vertices and
edges in the two projections of the bipartite graphs, without
calculating the projections themselves. This is useful to check how
much memory the projections would need if you have a large bipartite
graph.

`bipartite.projections`

calculates the actual projections.
You can use the `probe1`

argument to specify the order of the
projections in the result. By default vertex type `FALSE`

is the
first and `TRUE`

is the second.

##### Value

- A list of two undirected graphs. See details above.

##### concept

- Bipartite graph
- Two-mode network

##### Examples

```
## Projection of a full bipartite graph is a full graph
g <- graph.full.bipartite(10,5)
proj <- bipartite.projection(g)
graph.isomorphic(proj[[1]], graph.full(10))
graph.isomorphic(proj[[2]], graph.full(5))
```

*Documentation reproduced from package igraph, version 0.5.3, License: GPL (>= 2)*

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