R help - May 2008 - Histograms without bars

Hello

I'd like to plot a histogram of some data composed of real numbers. The
bin width I'm using is ~ 0.01, which results in high values in the y
axis, so that the area under each bar corresponds to the probability of
the data in that range.

Is is possible to plot points whose y coordinate correspond to that
probability, instead of plotting the histogram bars? In other words,
instead of having a bar of width 0.01 and height, say, 80, I'd like to
have a single point at y = 0.8.

I know I could use the values returned from hist() and calculate that
manually, but maybe there's a better way to do that. I've been using
prop.table() to plot these "histograms" for integer numbers, but now I
need binning and I'm not sure what is the best way to proceed.

Thanks in advance,
Andre

Hi Andre,

On May 19, 2008, at 4:28 PM, Andre Nathan wrote:
> Hello
>
> I'd like to plot a histogram of some data composed of real numbers.  
> The
> bin width I'm using is ~ 0.01, which results in high values in the y
> axis, so that the area under each bar corresponds to the  
> probability of
> the data in that range.
>
> Is is possible to plot points whose y coordinate correspond to that
> probability, instead of plotting the histogram bars? In other words,
> instead of having a bar of width 0.01 and height, say, 80, I'd like to
> have a single point at y = 0.8.
>
> I know I could use the values returned from hist() and calculate that
> manually, but maybe there's a better way to do that. I've been
using
> prop.table() to plot these "histograms" for integer numbers, but
now I
> need binning and I'm not sure what is the best way to proceed.
I would use ?cut to create a factor, followed with the usual  
prop.table (+ table) you have been using.
Unless you didn't want to have control over the precise binning?
> Thanks in advance,
> Andre
Haris Skiadas
Department of Mathematics and Computer Science
Hanover College

> Is is possible to plot points whose y coordinate correspond to that
> probability, instead of plotting the histogram bars? In other words,
> instead of having a bar of width 0.01 and height, say, 80, I'd like to
> have a single point at y = 0.8.
Very easily with ggplot2:

install.packages("ggplot2")
library(ggplot2)

qplot(carat, data=diamonds, stat="bin", geom="point")
qplot(carat, data=diamonds, stat="bin", geom="point",
binwidth=0.01)
# or with a line
qplot(carat, data=diamonds, stat="bin", geom="line")

# oh and by default the y axis gives count, to give probalilites use
qplot(carat, ..density.., data=diamonds, stat="bin",
geom="point")

Hadley
-- 
http://had.co.nz/