Plotting Likert-scale data with R

plot-likert.r

# Inputs
feature_names <- c("Feature 5", "Feature 4", "Feature 3", "Feature 2", "Feature 1")
num_features <- length(feature_names)
y <- array(c(10,4,1,0, 3,4,2,0, 1,2,8,1, 0,0,5,1,  1,2,5,3), dim=c(4,num_features))

# Calculate plot
num_neg_ratings <- 0
num_pos_ratings <- 0
for(i in 1:num_features) {
  num_neg_ratings = max(num_neg_ratings, sum(y[1:2,i]), sum(y[3:4,i]))
  num_pos_ratings = max(num_pos_ratings, sum(y[1:2,i]), sum(y[1:2,i]))
}
x <- array(0, dim=c(6, num_features))
for(i in 1:num_features) {
  x[1,  i] <- num_neg_ratings-sum(y[1:2, i])
  x[2:5,i] <- y[1:4, i]
  x[6,  i] <- num_pos_ratings-sum(y[3:4, i])
}

# do the plot
png("/tmp/jbl.png", width=600, height=280)
colors <- c("white","#c91629","#ff5c76","#4e9cff","#0557d6","white")
par(mar=c(4.1,10.1,4.1,4.1))
barplot(x, main="Feature Valence", axes=FALSE,
   col=colors, space=1.1, cex.axis=1.0, las=1, border=NA,
   names.arg=feature_names, cex=1.0, horiz=TRUE)
axis(
  side=1, # X axis
  at=c(0, num_neg_ratings/2, num_neg_ratings, num_neg_ratings+(num_pos_ratings/2), num_neg_ratings+num_pos_ratings),
  labels=c("Hate","Dislike",NA,"Like","Love")
)
dev.off()