chordDiagram() function of the
circlize package makes it a breeze to build chord diagrams from adjacency matrix in R.
The adjacency matrix displays all origins in rows, and all destinations in columns. Each cell is filled with a numeric value specifying the flow strength.
# Create an adjacency matrix: # a list of connections between 20 origin nodes, and 5 destination nodes: numbers <- sample(c(1:1000), 100, replace = T) data <- matrix( numbers, ncol=5) rownames(data) <- paste0("orig-", seq(1,20)) colnames(data) <- paste0("dest-", seq(1,5)) # Load the circlize library library(circlize) # Make the circular plot chordDiagram(data, transparency = 0.5)
Another common format to store flow information iis the edge list. Basically, all connections are stored one by one in a 2 columns file, listing the origin and destination of each.
chordDiagram() function expects an adjacency matrix as input, it is required to use the
table() function for reformating, as described below:
# Create an edge list: a list of connections between 10 origin nodes, and 10 destination nodes: origin <- paste0("orig ", sample(c(1:10), 20, replace = T)) destination <- paste0("dest ", sample(c(1:10), 20, replace = T)) data <- data.frame(origin, destination) # Transform input data in a adjacency matrix adjacencyData <- with(data, table(origin, destination)) # Charge the circlize library library(circlize) # Make the circular plot chordDiagram(adjacencyData, transparency = 0.5)