DiagrammeR (version 0.9.2)

add_edges_from_table: Add edges and attributes to graph from a table

Description

Add edges and their attributes to an existing graph object from data in a CSV file or a data frame.

Usage

add_edges_from_table(graph, table, from_col, to_col, ndf_mapping,
  rel_col = NULL, set_rel = NULL, drop_cols = NULL)

Arguments

graph

a graph object of class dgr_graph.

table

either a path to a CSV file, or, a data frame object.

from_col

the name of the table column from which edges originate.

to_col

the name of the table column to which edges terminate.

ndf_mapping

a single character value for the mapping of the from and to columns in the external table (supplied as from_col and to_col, respectively) to a column in the graph's internal node data frame (ndf).

rel_col

an option to apply a column of data in the table as rel attribute values.

set_rel

an optional string to apply a rel attribute to all edges created from the table records.

drop_cols

an optional character vector for dropping columns from the incoming data.

Value

a graph object of class dgr_graph.

Examples

# NOT RUN {
# Create an empty graph and then add
# nodes to it from a CSV file; in this case
# we are using the `currencies` CSV file
# that's available in the package
graph <-
  create_graph() %>%
  add_nodes_from_table(
    system.file("extdata", "currencies.csv",
                package = "DiagrammeR"))

# Now we want to add edges to the graph
# using a similar CSV file that contains
# exchange rates between several currencies;
# the common attribute is the ISO-4217
# currency code
graph_1 <-
  graph %>%
  add_edges_from_table(
    system.file("extdata", "usd_exchange_rates.csv",
                package = "DiagrammeR"),
    from_col = from_currency,
    to_col = to_currency,
    ndf_mapping = iso_4217_code)

# View part of the graph's internal edge data
# frame (edf) using `get_edge_df()`
graph_1 %>%
  get_edge_df() %>%
  head()
#>   id from to  rel cost_unit
#> 1  1  148  1 <NA>  0.272300
#> 2  2  148  2 <NA>  0.015210
#> 3  3  148  3 <NA>  0.008055
#> 4  4  148  4 <NA>  0.002107
#> 5  5  148  5 <NA>  0.565000
#> 6  6  148  6 <NA>  0.006058

# If you would like to assign any of the table's
# columns as `rel` attribute, this can done with
# the `rel_col` argument; to set a static `rel`
# attribute for all edges, use `set_rel`
graph_2 <-
  graph %>%
  add_edges_from_table(
    system.file("extdata", "usd_exchange_rates.csv",
                package = "DiagrammeR"),
    from_col = from_currency,
    to_col = to_currency,
    ndf_mapping = iso_4217_code,
    set_rel = "from_usd")

# View part of the graph's internal edge data
# frame (edf) using `get_edge_df()`
graph_2 %>%
  get_edge_df() %>%
  head()
#>   id from to      rel cost_unit
#> 1  1  148  1 from_usd  0.272300
#> 2  2  148  2 from_usd  0.015210
#> 3  3  148  3 from_usd  0.008055
#> 4  4  148  4 from_usd  0.002107
#> 5  5  148  5 from_usd  0.565000
#> 6  6  148  6 from_usd  0.006058
# }