# subgraph: Subgraph of a graph In igraph: Network Analysis and Visualization

## Description

`subgraph` creates a subgraph of a graph, containing only the specified vertices and all the edges among them.

## Usage

 ```1 2 3 4 5 6 7 8 9``` ```subgraph(graph, v) induced_subgraph( graph, vids, impl = c("auto", "copy_and_delete", "create_from_scratch") ) subgraph.edges(graph, eids, delete.vertices = TRUE) ```

## Arguments

 `graph` The original graph. `v` Numeric vector, the vertices of the original graph which will form the subgraph. `vids` Numeric vector, the vertices of the original graph which will form the subgraph. `impl` Character scalar, to choose between two implementation of the subgraph calculation. ‘`copy_and_delete`’ copies the graph first, and then deletes the vertices and edges that are not included in the result graph. ‘`create_from_scratch`’ searches for all vertices and edges that must be kept and then uses them to create the graph from scratch. ‘`auto`’ chooses between the two implementations automatically, using heuristics based on the size of the original and the result graph. `eids` The edge ids of the edges that will be kept in the result graph. `delete.vertices` Logical scalar, whether to remove vertices that do not have any adjacent edges in `eids`.

## Details

`induced_subgraph` calculates the induced subgraph of a set of vertices in a graph. This means that exactly the specified vertices and all the edges between them will be kept in the result graph.

`subgraph.edges` calculates the subgraph of a graph. For this function one can specify the vertices and edges to keep. This function will be renamed to `subgraph` in the next major version of igraph.

The `subgraph` function does the same as `induced.graph` currently (assuming ‘`auto`’ as the `impl` argument), but it is deprecated and will be removed in the next major version of igraph.

## Value

A new graph object.

## Author(s)

Gabor Csardi csardi.gabor@gmail.com

## Examples

 ```1 2 3``` ```g <- make_ring(10) g2 <- induced_subgraph(g, 1:7) g3 <- subgraph.edges(g, 1:5, 1:5) ```

igraph documentation built on March 19, 2020, 5:13 p.m.