R help - Feb 2009 - bar plot/ histogram

Hi all,

I would like to construct plot of the distribution of N, where N range
from 1 to 10. I couldn't just use the hist(), as I want the categories
for the bars are: 1, 2, 3, 4, >=5. So this will be a bar plot with 5
bars, and the height of the bar will be the frequency of N. (eg bar#1
will be the frequency of N=1, bar #2 will be frequency of N=2, and
bar#5 will be the frequency of N>=5).

Thanks in advance for your help!

SY

on 02/11/2009 12:10 PM phoebe kong wrote:
> Hi all,
> 
> I would like to construct plot of the distribution of N, where N range
> from 1 to 10. I couldn't just use the hist(), as I want the categories
> for the bars are: 1, 2, 3, 4, >=5. So this will be a bar plot with 5
> bars, and the height of the bar will be the frequency of N. (eg bar#1
> will be the frequency of N=1, bar #2 will be frequency of N=2, and
> bar#5 will be the frequency of N>=5).
> 
> Thanks in advance for your help!
> 
> SY
You can use cut() to break up your data into the desired groupings and
then use barplot().

set.seed(1)

data <- sample(10, 100, replace = TRUE)
> table(data)
data
 1  2  3  4  5  6  7  8  9 10
 7  6 11 14 14  5 11 15 11  6
> cut(data, breaks = c(0:4, Inf), labels = c(1:4, ">=5"))
  [1] 3   4   >=5 >=5 3   >=5 >=5 >=5 >=5 1   3   2   >=5 4
>=5 >=5
 [17] >=5 >=5 4   >=5 >=5 3   >=5 2   3   4   1   4   >=5 4  
>=5 >=5
 [33] >=5 2   >=5 >=5 >=5 2   >=5 >=5 >=5 >=5 >=5
>=5 >=5 >=5 1   >=5
 [49] >=5 >=5 >=5 >=5 >=5 3   1   1   4   >=5 >=5 >=5
>=5 3   >=5 4
 [65] >=5 3   >=5 >=5 1   >=5 4   >=5 4   4   >=5 >=5
>=5 4   >=5 >=5
 [81] >=5 >=5 4   4   >=5 3   >=5 2   3   2   3   1   >=5 >=5
>=5 >=5
 [97] >=5 >=5 >=5 >=5
Levels: 1 2 3 4 >=5
> table(cut(data, breaks = c(0:4, Inf), labels = c(1:4, ">=5")))
  1   2   3   4 >=5
  7   6  11  14  62


barplot(table(cut(data, breaks = c(0:4, Inf), labels = c(1:4,
">=5"))))


See ?cut for more information.

HTH,

Marc Schwartz

You can still use hist, just provide your own breaks:

mydata <- sample(1:10, 100, TRUE, 10:1)
br <- c( 0.5:4.5, 10.5 )
hist(mydata, breaks=br, xaxt='n')
axis(1, at= c(1:4, mean(5:10)), c( 1:4, '5-10'))
box(bty='l')

hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of phoebe kong
> Sent: Wednesday, February 11, 2009 11:11 AM
> To: r-help
> Subject: [R] bar plot/ histogram
> 
> Hi all,
> 
> I would like to construct plot of the distribution of N, where N range
> from 1 to 10. I couldn't just use the hist(), as I want the categories
> for the bars are: 1, 2, 3, 4, >=5. So this will be a bar plot with 5
> bars, and the height of the bar will be the frequency of N. (eg bar#1
> will be the frequency of N=1, bar #2 will be frequency of N=2, and
> bar#5 will be the frequency of N>=5).
> 
> Thanks in advance for your help!
> 
> SY
> 
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