# mst

##### Minimum spanning tree

A subgraph of a connected graph is a *minimum spanning tree* if it is
tree, and the sum of its edge weights are the minimal among all tree
subgraphs of the graph. A minimum spanning forest of a graph is the graph
consisting of the minimum spanning trees of its components.

- Keywords
- graphs

##### Usage

`mst(graph, weights = NULL, algorithm = NULL, ...)`

##### Arguments

- graph
The graph object to analyze.

- weights
Numeric algorithm giving the weights of the edges in the graph. The order is determined by the edge ids. This is ignored if the

`unweighted`

algorithm is chosen. Edge weights are interpreted as distances.- algorithm
The algorithm to use for calculation.

`unweighted`

can be used for unwieghted graphs, and`prim`

runs Prim's algorithm for weighted graphs. If this is`NULL`

then igraph tries to select the algorithm automatically: if the graph has an edge attribute called`weight`

of the`weights`

argument is not`NULL`

then Prim's algorithm is chosen, otherwise the unwweighted algorithm is performed.- …
Additional arguments, unused.

##### Details

If the graph is unconnected a minimum spanning forest is returned.

##### Value

A graph object with the minimum spanning forest. (To check that it
is a tree check that the number of its edges is `vcount(graph)-1`

.)
The edge and vertex attributes of the original graph are preserved in the
result.

##### References

Prim, R.C. 1957. Shortest connection networks and some
generalizations *Bell System Technical Journal*, 37 1389--1401.

##### See Also

##### Examples

```
# NOT RUN {
g <- sample_gnp(100, 3/100)
g_mst <- mst(g)
# }
```

*Documentation reproduced from package igraph, version 1.2.2, License: GPL (>= 2)*