DiagrammeR (version 0.8.4)

join_edge_attrs: Join new edge attribute values using a data frame

Description

Join new edge attribute values in a left join using a data frame. The use of a left join in this function allows for no possibility that edges in the graph might be removed after the join.

Usage

join_edge_attrs(graph, df, by_graph = NULL, by_df = NULL)

Arguments

graph

a graph object of class

df

the data frame to use for joining. dgr_graph that is created using create_graph.

by_graph

optional specification of the column in the graph's internal edge data frame for the left join. If both by_graph and by_df are not provided, then a natural join will occur if there are columns in the graph's edf and in df with identical names.

by_df

optional specification of the column in df for the left join. If both by_graph and by_df are not provided, then a natural join will occur if there are columns in the graph's edf and in df with identical names.

Value

a graph object of class dgr_graph.

Examples

library(magrittr)

# Create a simple graph
graph <-
  create_graph() %>%
  add_n_nodes(5) %>%
  add_edges_w_string("1->2 1->3 2->4 2->5 3->5")

# Create a data frame with node ID values
# representing the graph edges (with `from` and `to`
# columns), and, a set of numeric values
df <-
  data.frame(from = c(1, 1, 2, 2, 3),
             to = c(2, 3, 4, 5, 5),
             values = rnorm(5, 5))

# Join the values in the data frame to the
# graph's edges; this works as a left join using
# identically-named columns in the graph and the df
# (in this case `from` and `to` are common to both)
graph <-
  graph %>% join_edge_attrs(df)

# Get the graph's internal edf to show that the
# join has been made
get_edge_df(graph)
#>   from to rel           values
#> 1    1  2     7.13009924330664
#> 2    1  3     4.91228554626235
#> 3    2  4     3.53310530960626
#> 4    2  5      5.6516614809259
#> 5    3  5     5.87955663602654