[R] hist and truehist

Gregor GORJANC gregor.gorjanc at bfro.uni-lj.si
Mon Nov 29 10:27:55 CET 2004

Peter thanks for the response.

So the results from hist(mydata) and truehist(mydata, h = .5) are the 
same. OK, but the sum of densities or intensities, for case that I gave, 
don't sum to 1 but to 2. Look bellow. I have an example where these 
density values are also up to 4 and sum to 5 (I have attached the PDF of 
that plot).

This is really frustrating for me. What are actually these intensisties 
and densities, how are they calculated. Why are they the same?

mydata <- c(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,3,4,5)
# histogram with frequencies
# histogram with ratios or probabilities
hist(mydata, freq = F) # what are that values on vertical axis
# lets take a look at values behind
x <-hist(mydata, freq = F, plot = F); x
# Sum values
[1] 2.000000
R > sum(x$density)
[1] 2.000000

When I think of histogram (the one not with frequencies) I think of
gathering records into "some classes" and then divide the number of
records in each "class" by total number of all records. This is not the
case in hist().

Sorry for being pain in the ..., but this is really weird. Above that 
R-team is really doing a great job. Thanks for such a good tool!

Lep pozdrav / With regards / Con respeto,
     Gregor GORJANC

University of Ljubljana
Biotechnical Faculty       URI: http://www.bfro.uni-lj.si
Zootechnical Department    mail: gregor.gorjanc <at> bfro.uni-lj.si
Groblje 3                  tel: +386 (0)1 72 17 861
SI-1230 Domzale            fax: +386 (0)1 72 41 005
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