Visualise Data Flow with a Sankey Diagram — plot

plot_sankey enhances the networkD3::sankeyNetwork function, utilising htmlwidgets to create an interactive Sankey diagram. This type of flow diagram is particularly effective for illustrating data movement or transfer between different entities (nodes), such as in the distribution of votes across elections or in preferential voting systems.

Usage

plot_sankey(
  data,
  source,
  target,
  value,
  units = "",
  colours = colour_pal("catExtended"),
  fontSize = 20,
  fontFamily = "Calibri",
  nodeWidth = 20,
  nodePadding = 10,
  margin = list(top = 0, right = 0, bottom = 0, left = 0),
  width = 1200,
  height = 800,
  shiftLabel = NULL,
  heading = NULL,
  sourceTitle = NULL,
  targetTitle = NULL
)

Arguments

data: A data frame containing the flow data, where each row represents a unique flow from a source to a target node.
source: The column in data representing the source nodes.
target: The column in data representing the target nodes.
value: The column in data representing the flow's magnitude or volume.
units: A string indicating the units for value, displayed in the tooltip. Defaults to an empty string, implying no units.
colours: A list or vector of colours for nodes and links in the diagram, either as hexadecimal codes or colour names. Can be a named list for specific node colour mapping.
fontSize: Font size for text in the diagram.
fontFamily: Font family for text in the diagram.
nodeWidth: Width of nodes in the diagram.
nodePadding: Padding between nodes in the diagram.
margin: Margins around the diagram, specified as a list.
width: Width of the plot in pixels.
height: Height of the plot in pixels.
shiftLabel: Numeric value to adjust the position of labels; NA for auto-placement.
heading: An optional string for the main title of the Sankey diagram.
sourceTitle: An optional string for labeling the source nodes.
targetTitle: An optional string for labeling the target nodes.

Value

An interactive Sankey diagram as an HTML widget, which can be used in R Markdown documents, Shiny applications, or the R console. The diagram provides a visual representation of the flow data, with customisable aspects such as colours, fonts, and node dimensions.

Examples

if (FALSE) { # \dontrun{
  # Example: Visualising the flow of votes between parties
  plot_sankey(data = election_data,
              source = "Party_Previous_Election",
              target = "Party_Current_Election",
              value = "Number_of_Votes",
              colours = c("Labour" = "red", "Green" = "green", "National" = "blue"),
              heading = "Election Vote Flow",
              sourceTitle = "Previous Election",
              targetTitle = "Current Election")
} # }