add_nodes_attr {graph4lg}

Add attributes to the nodes of a graph

Description

The function adds attributes to the nodes of a graph from either an object of class data.frame or from a shapefile layer. The node IDs in the input objects must be the same as in the graph object.

Usage

add_nodes_attr(
  graph,
  input = "df",
  data,
  dir_path = NULL,
  layer = NULL,
  index = "Id",
  include = "all"
)

Arguments

graph

A graph object of class igraph.

input

A character string indicating the nature of the input data from which come the attributes to add to the nodes.

• If 'input = "shp"', then attributes come from the attribute table of a shapefile layer of type point.

• If 'input = "df"', then attributes come from an object of class data.frame

In both cases, input attribute table or dataframe must have a column with the exact same values as the node IDs.

data

(only if 'input = "df"') The name of the object of class data.frame with the attributes to add to the nodes.

dir_path

(only if 'input = "shp"') The path (character string) to the directory containing the shapefile layer of type point whose attribute table contains the attributes to add to the nodes.

layer

(only if 'input = "shp"') The name (character string) of the shapefile layer of type point (without extension, ex.: "nodes" refers to "nodes.shp" layer) whose attribute table contains the attributes to add to the nodes.

index

The name (character string) of the column with the nodes names in the input data (column of the attribute table or of the dataframe).

include

A character string (vector) indicating which columns of the input data will be added as nodes' attributes. By default, 'include = "all"', i.e. every column of the input data is added. Alternatively, 'include' can be a vector with the names of the columns to add (ex.: "c('x', 'y', 'pop_name')").

Details

The graph can be created with the function graphab_to_igraph by importing output from Graphab projects. Values of the metrics computed at the node level with Graphab can then be added to such a graph with this function.

Value

A graph object of class igraph

Author(s)

P. Savary

Examples

data("data_tuto")
graph <- data_tuto[[3]]
df_nodes <- data.frame(Id = igraph::V(graph)$name,
                       Area = runif(50, min = 10, max = 60))
graph <- add_nodes_attr(graph,
                        data = df_nodes,
                        input = "df",
                        index = "Id",
                        include = "Area")