Question

I want to create intervals (discretize/bin) of continuous variables to plot a choropleth map using ggplot. After reading various threads, I decided to use cut and quantile to eliminate the problems of: a) manually creating bins, and b) taking care of dominant states (otherwise, I had to manually to create bins and see the map and readjust the bins).

However, I am facing another problem now. Intervals coming out of cut are hardly pretty. So, I am trying to follow this example and this example to come up with my pretty labels.

Here is my list:

x <- seq(1,50)

Rounded quantiles:

qs_x <- round(quantile(x, probs=c(seq(0,0.8,by=0.2),0.9)))

which results:

 0% 20% 40% 60% 80% 90% 
 1  11  21  30  40  45 

Using these cuts, I want to come up with these labels:

1-11, 12-21, 22-30, 31-40, 41-45, 45+

I am sure there is an easy solution to convert a list using some apply function, but I am not well-versed with those functions.

Help appreciated.

Answer 1

A 3-liner produces the output you want, without using apply.

labels <- paste(qs_x+1, qs_x[-1], sep="-")
labels[1] <- paste(qs_x[1], qs_x[2], sep="-")
labels[length(labels)] <- paste(tail(qs_x, 1), "+", sep = "")

The first line constructs labels of the form (x1 + 1) - x2, the second line fixes the first label, and the third line fixes the last label. Here is the output

> labels
[1] "1-11"  "12-21" "22-30" "31-40" "41-45" "45+"