# graph_from_incidence_matrix

##### Create graphs from an incidence matrix

`graph_from_incidence_matrix`

creates a bipartite igraph graph from an incidence
matrix.

- Keywords
- graphs

##### Usage

```
graph_from_incidence_matrix(incidence, directed = FALSE,
mode = c("all", "out", "in", "total"), multiple = FALSE,
weighted = NULL, add.names = NULL)
```from_incidence_matrix(...)

##### Arguments

- incidence
The input incidence matrix. It can also be a sparse matrix from the

`Matrix`

package.- directed
Logical scalar, whether to create a directed graph.

- mode
A character constant, defines the direction of the edges in directed graphs, ignored for undirected graphs. If ‘

`out`

’, then edges go from vertices of the first kind (corresponding to rows in the incidence matrix) to vertices of the second kind (columns in the incidence matrix). If ‘`in`

’, then the opposite direction is used. If ‘`all`

’ or ‘`total`

’, then mutual edges are created.- multiple
Logical scalar, specifies how to interpret the matrix elements. See details below.

- weighted
This argument specifies whether to create a weighted graph from the incidence matrix. If it is

`NULL`

then an unweighted graph is created and the`multiple`

argument is used to determine the edges of the graph. If it is a character constant then for every non-zero matrix entry an edge is created and the value of the entry is added as an edge attribute named by the`weighted`

argument. If it is`TRUE`

then a weighted graph is created and the name of the edge attribute will be ‘`weight`

’.- add.names
A character constant,

`NA`

or`NULL`

.`graph_from_incidence_matrix`

can add the row and column names of the incidence matrix as vertex attributes. If this argument is`NULL`

(the default) and the incidence matrix has both row and column names, then these are added as the ‘`name`

’ vertex attribute. If you want a different vertex attribute for this, then give the name of the attributes as a character string. If this argument is`NA`

, then no vertex attributes (other than type) will be added.- ...
Passed to

`graph_from_incidence_matrix`

.

##### Details

Bipartite graphs have a ‘`type`

’ vertex attribute in igraph,
this is boolean and `FALSE`

for the vertices of the first kind and
`TRUE`

for vertices of the second kind.

`graph_from_incidence_matrix`

can operate in two modes, depending on the
`multiple`

argument. If it is `FALSE`

then a single edge is
created for every non-zero element in the incidence matrix. If
`multiple`

is `TRUE`

, then the matrix elements are rounded up to
the closest non-negative integer to get the number of edges to create
between a pair of vertices.

##### Value

A bipartite igraph graph. In other words, an igraph graph that has a
vertex attribute `type`

.

##### See Also

`make_bipartite_graph`

for another way to create bipartite
graphs

##### Examples

```
# NOT RUN {
inc <- matrix(sample(0:1, 15, repl=TRUE), 3, 5)
colnames(inc) <- letters[1:5]
rownames(inc) <- LETTERS[1:3]
graph_from_incidence_matrix(inc)
# }
```

*Documentation reproduced from package igraph, version 1.2.4.2, License: GPL (>= 2)*