The new edges are given as a vertex sequence, e.g. internal
numeric vertex ids, or vertex names. The first edge points from
`edges[1]`

to `edges[2]`

, the second from `edges[3]`

to `edges[4]`

, etc.

## Usage

`add_edges(graph, edges, ..., attr = list())`

## Arguments

- graph
The input graph

- edges
The edges to add, a vertex sequence with even number of vertices.

- ...
Additional arguments, they must be named, and they will be added as edge attributes, for the newly added edges. See also details below.

- attr
A named list, its elements will be added as edge attributes, for the newly added edges. See also details below.

## Details

If attributes are supplied, and they are not present in the graph,
their values for the original edges of the graph are set to `NA`

.

## See also

Other functions for manipulating graph structure:
`+.igraph()`

,
`add_vertices()`

,
`complementer()`

,
`compose()`

,
`connect()`

,
`contract()`

,
`delete_edges()`

,
`delete_vertices()`

,
`difference()`

,
`difference.igraph()`

,
`disjoint_union()`

,
`edge()`

,
`igraph-minus`

,
`intersection()`

,
`intersection.igraph()`

,
`path()`

,
`permute()`

,
`rep.igraph()`

,
`reverse_edges()`

,
`simplify()`

,
`union()`

,
`union.igraph()`

,
`vertex()`

## Examples

```
g <- make_empty_graph(n = 5) %>%
add_edges(c(
1, 2,
2, 3,
3, 4,
4, 5
)) %>%
set_edge_attr("color", value = "red") %>%
add_edges(c(5, 1), color = "green")
E(g)[[]]
#> + 5/5 edges from 456b0ec:
#> tail head tid hid color
#> 1 1 2 1 2 red
#> 2 2 3 2 3 red
#> 3 3 4 3 4 red
#> 4 4 5 4 5 red
#> 5 5 1 5 1 green
plot(g)
```