Force R to plot histogram as probability (relative frequency)

Question

I am having trouble plotting a histogram as a pdf (probability)

I want the sum of all the pieces to equal an area of one so it\'s easier to compare across datasets. For

Answer 1

I observed that, in histogram density = relative frequency / corresponding bin width

Example 1:

nums = c(10, 41, 10, 28, 22, 8, 31, 3, 9, 9)

h2 = hist(nums, plot=F)

rf2 = h2$counts / sum(h2$counts)

d2 = rf2 / diff(h2$breaks)

h2$density

[1] 0.06 0.00 0.02 0.01 0.01

d2

[1] 0.06 0.00 0.02 0.01 0.01

Example 2:

nums = c(10, 41, 10, 28, 22, 8, 31, 3, 9, 9)

h3 = hist(nums, plot=F, breaks=c(1,30,40,50))

rf3 = h3$counts / sum(h3$counts)

d3 = rf3 / diff(h3$breaks)

h3$density

[1] 0.02758621 0.01000000 0.01000000

d3

[1] 0.02758621 0.01000000 0.01000000