mutate_edge_attrs_ws {DiagrammeR} | R Documentation

## Mutate edge attribute values for a selection of edges

### Description

Within a graph's internal edge data frame (edf), mutate edge attribute values only for edges in a selection by using one or more expressions.

### Usage

    mutate_edge_attrs_ws(graph, ...)

### Arguments

`graph` | a graph object of class `dgr_graph`.
`...` | expressions used for the mutation of edge attributes. LHS of each expression is either an existing or new edge attribute name. The RHS can consist of any valid R code that uses edge attributes as variables. Expressions are evaluated in the order provided, so, edge attributes created or modified are ready to use in subsequent expressions.

### Value

a graph object of class `dgr_graph`.

### Examples

    # Create a graph with 3 edges
    # and then select edge `1`
    graph <-
      create_graph() %>%
      add_path(n = 4) %>%
      set_edge_attrs(
        edge_attr = width,
        values = c(3.4, 2.3, 7.2)) %>%
      select_edges(edges = 1)

    # Get the graph's internal edf
    # to show which edge attributes
    # are available
    graph %>%
      get_edge_df()

    # Mutate the `width` edge
    # attribute for the edges
    # only in the active selection
    # of edges (edge `1`); here,
    # we divide each value in the
    # selection by 2
    graph <-
      graph %>%
      mutate_edge_attrs_ws(
        width = width / 2)

    # Get the graph's internal
    # edf to show that the edge
    # attribute `width` had its
    # values changed
    graph %>%
      get_edge_df()

    # Create a new edge attribute,
    # called `length`, that is the
    # log of values in `width` plus
    # 2 (and, also, round all values
    # to 2 decimal places)
    graph <-
      graph %>%
      clear_selection() %>%
      select_edges(edges = 2:3) %>%
      mutate_edge_attrs_ws(
        length = (log(width) + 2) %>%
                   round(2))

    # Get the graph's internal edf
    # to show that the edge attribute
    # values had been mutated only
    # for edges `2` and `3` (since
    # edge `1` is excluded, an NA
    # value is applied)
    graph %>%
      get_edge_df()

    # Create a new edge attribute
    # called `area`, which is the
    # product of the `width` and
    # `length` attributes
    graph <-
      graph %>%
      mutate_edge_attrs_ws(
        area = width * length)

    # Get the graph's internal edf
    # to show that the edge attribute
    # values had been multiplied
    # together (with new attr `area`)
    # for nodes `2` and `3`
    graph %>%
      get_edge_df()

    # We can invert the selection
    # and mutate edge `1` several
    # times to get an `area` value
    # for that edge
    graph <-
      graph %>%
      invert_selection() %>%
      mutate_edge_attrs_ws(
        length = (log(width) + 5) %>%
                   round(2),
        area = width * length)

    # Get the graph's internal edf
    # to show that the 2 mutations
    # occurred for edge `1`, yielding
    # non-NA values for its edge
    # attributes without changing
    # those of the other edges
    graph %>%
      get_edge_df()

[Package DiagrammeR version 1.0.1 Index]