select_edges {DiagrammeR} | R Documentation

## Select edges in a graph

### Description

Select edges from a graph object of class `dgr_graph`.

### Usage

    select_edges(graph, conditions = NULL, set_op = "union", from = NULL,
      to = NULL, edges = NULL)

### Arguments

`graph` | a graph object of class `dgr_graph`.
`conditions` | an option to use filtering conditions for the retrieval of edges.
`set_op` | the set operation to perform upon consecutive selections of graph nodes. This can either be as a `union` (the default), as an intersection of selections with `intersect`, or, as a `difference` on the previous selection, if it exists.
`from` | an optional vector of node IDs from which the edge is outgoing for filtering the list of edges present in the graph.
`to` | an optional vector of node IDs to which the edge is incoming for filtering the list of edges present in the graph.
`edges` | an optional vector of edge IDs for filtering the list of edges present in the graph.

### Value

a graph object of class `dgr_graph`.

### Examples

    # Create a node data frame (ndf)
    ndf <-
      create_node_df(
        n = 4,
        type = "basic",
        label = TRUE,
        value = c(3.5, 2.6, 9.4, 2.7))

    # Create an edge data frame (edf)
    edf <-
      create_edge_df(
        from = c(1, 2, 3),
        to = c(4, 3, 1),
        rel = c("a", "z", "a"),
        value = c(6.4, 2.9, 5.0))

    # Create a graph with the ndf and edf
    graph <-
      create_graph(
        nodes_df = ndf,
        edges_df = edf)

    # Explicitly select the edge `1`->`4`
    graph <-
      graph %>%
      select_edges(
        from = 1,
        to = 4)

    # Verify that an edge selection has been made
    # using the `get_selection()` function
    graph %>%
      get_selection()

    # Select edges based on the relationship label
    # being `z`
    graph <-
      graph %>%
      clear_selection() %>%
      select_edges(
        conditions = rel == "z")

    # Verify that an edge selection has been made, and
    # recall that the `2`->`3` edge uniquely has the
    # `z` relationship label
    graph %>%
      get_selection()

    # Select edges based on the edge value attribute
    # being greater than 3.0 (first clearing the current
    # selection of edges)
    graph <-
      graph %>%
      clear_selection() %>%
      select_edges(
        conditions = value > 3.0)

    # Verify that the correct edge selection has been
    # made; in this case, edges `1`->`4` and
    # `3`->`1` have values for `value` > 3.0
    graph %>%
      get_selection()

[Package DiagrammeR version 1.0.1 Index]