[R] A question on histogram - area much less than 1

[Rolf Turner]

Why do you say that the area is much lower than 1?
It is exactly equal to 1.

How did you calculate this area?

Your code seems extremely convoluted and confused.

You could construct your (rather bizarre) vector Y1 much
more simply as

Y1 <- rep((0.5 + 0:9)*35,c(277,146,99,80,69,63,52,53,55,98))

What do you think you are accomplishing via that call to par()
given *after* the plotting has been done?

Why set ylim to a value that is so incommensurate with the
heights of the histogram bars?

     cheers,

         Rolf Turner

On 12/03/12 20:42, jpm miao wrote:
> Hello,
>
>     I have problem running the histogram function "hist". The area under the
> histogram is much lower than 1. Could anyone tell me what the problem is?
> Thanks,
>     (The total number of observation is 992 (close to 1000), so the
> probability that 0<Y1<35 is approximately 0.277)
Why are you approximating?  The empirical probability is exactly
equal to 277/992 = 0.2792339.
> miao
>
>
>
> rm(list=ls())
> par(mfrow=c(1, 1))
> Y<- cbind(matrix(35*0.5,1,277), matrix(35*1.5, 1, 146), matrix(35*2.5, 1,
> 99), matrix(35*3.5,1,80), matrix(35*4.5, 1, 69), matrix(35*5.5, 1, 63),
> matrix(35*6.5, 1, 52), matrix(35*7.5,1, 53), matrix(35*8.5, 1, 55),
> matrix(35*9.5, 1, 98))
> Y1<-as.vector(Y)
> par(mar=c(4.5, 4.1, 3.1, 0))
> hist(Y1, breaks=seq(0, 350, by=35), ylim=c(0, 0.3), col="grey80",
> freq=FALSE)
> par(mar=c(5.1, 4.1, 4.1, 2.1))