# E: Edges of a graph In igraph: Network Analysis and Visualization

 E R Documentation

## Edges of a graph

### Description

An edge sequence is a vector containing numeric edge ids, with a special class attribute that allows custom operations: selecting subsets of edges based on attributes, or graph structure, creating the intersection, union of edges, etc.

### Usage

``````E(graph, P = NULL, path = NULL, directed = TRUE)
``````

### Arguments

 `graph` The graph. `P` A list of vertices to select edges via pairs of vertices. The first and second vertices select the first edge, the third and fourth the second, etc. `path` A list of vertices, to select edges along a path. Note that this only works reliable for simple graphs. If the graph has multiple edges, one of them will be chosen arbitrarily to be included in the edge sequence. `directed` Whether to consider edge directions in the `P` argument, for directed graphs.

### Details

Edge sequences are usually used as igraph function arguments that refer to edges of a graph.

An edge sequence is tied to the graph it refers to: it really denoted the specific edges of that graph, and cannot be used together with another graph.

An edge sequence is most often created by the `E()` function. The result includes edges in increasing edge id order by default (if. none of the `P` and `path` arguments are used). An edge sequence can be indexed by a numeric vector, just like a regular R vector. See links to other edge sequence operations below.

### Value

An edge sequence of the graph.

### Indexing edge sequences

Edge sequences mostly behave like regular vectors, but there are some additional indexing operations that are specific for them; e.g. selecting edges based on graph structure, or based on edge attributes. See `[.igraph.es` for details.

### Querying or setting attributes

Edge sequences can be used to query or set attributes for the edges in the sequence. See `\$.igraph.es()` for details.

Other vertex and edge sequences: `V()`, `as_ids()`, `igraph-es-attributes`, `igraph-es-indexing2`, `igraph-es-indexing`, `igraph-vs-attributes`, `igraph-vs-indexing2`, `igraph-vs-indexing`, `print.igraph.es()`, `print.igraph.vs()`

### Examples

``````# Edges of an unnamed graph
g <- make_ring(10)
E(g)

# Edges of a named graph
g2 <- make_ring(10) %>%
set_vertex_attr("name", value = letters[1:10])
E(g2)
``````

igraph documentation built on Aug. 10, 2023, 9:08 a.m.