# make_line_graph

From igraph v1.2.4.1
by Gabor Csardi

##### Line graph of a graph

This function calculates the line graph of another graph.

- Keywords
- graphs

##### Usage

`make_line_graph(graph)`line_graph(...)

##### Arguments

- graph
The input graph, it can be directed or undirected.

- ...
Passed to

`make_line_graph`

.

##### Details

The line graph `L(G)`

of a `G`

undirected graph is defined as
follows. `L(G)`

has one vertex for each edge in `G`

and two
vertices in `L(G)`

are connected by an edge if their corresponding
edges share an end point.

The line graph `L(G)`

of a `G`

directed graph is slightly
different, `L(G)`

has one vertex for each edge in `G`

and two
vertices in `L(G)`

are connected by a directed edge if the target of
the first vertex's corresponding edge is the same as the source of the
second vertex's corresponding edge.

##### Value

A new graph object.

##### Examples

```
# NOT RUN {
# generate the first De-Bruijn graphs
g <- make_full_graph(2, directed=TRUE, loops=TRUE)
make_line_graph(g)
make_line_graph(make_line_graph(g))
make_line_graph(make_line_graph(make_line_graph(g)))
# }
```

*Documentation reproduced from package igraph, version 1.2.4.1, License: GPL (>= 2)*

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