Rotate labels in a chordDiagram (R circlize)

Question

Here is some code from the circlize package for creating a chord diagram.Right now the labels are parallel to the edge of the circle. Is it possible to rotate

Answer 1

Based on your example data, here's one way to do it:

grid.col <- setNames(rainbow(length(unlist(dimnames(mat)))), union(rownames(mat), colnames(mat)))
par(mar = c(0, 0, 0, 0), mfrow = c(1, 2))

# original image
chordDiagram(mat, grid.col = grid.col) 

# now, the image with rotated labels
chordDiagram(mat, annotationTrack = "grid", preAllocateTracks = 1, grid.col = grid.col)
circos.trackPlotRegion(track.index = 1, panel.fun = function(x, y) {
  xlim = get.cell.meta.data("xlim")
  ylim = get.cell.meta.data("ylim")
  sector.name = get.cell.meta.data("sector.index")
  circos.text(mean(xlim), ylim[1] + .1, sector.name, facing = "clockwise", niceFacing = TRUE, adj = c(0, 0.5))
  circos.axis(h = "top", labels.cex = 0.5, major.tick.percentage = 0.2, sector.index = sector.name, track.index = 2)
}, bg.border = NA)

Result: