[R] Re: Bar plot with variable width (down a drill hole) - now missing intervals?

[Phillip J. Allen]

Hi again,

Thanks Ted and Marc its works.  But of course after pulling in in some 
real life data I discoverd one hitch.  Often there are missing 
intervals.  For example:
from <- c(0, 1.2, 4.0, 4.2, 5.0, 25.0, 30.1, 45)
to <- c(1.2, 4.0, 4.2, 5.0, 25, 30.1, 36.2, 50)
intensity <- c(0, 1, 3, 2, 1, 0, 2, 5)
barplot(intensity, width = -(to - from),
        space = 0, horiz = TRUE, ylim = c(-40, 0))

And it appears a barplot() is just stacking bars one on top the other 
and the help page doesn't indicate anyway to position the bar along the 
y-axis.  So does anyone have a nifty trick to to fill in blank gaps?  At 
least my database can check for "overlaping" intervals before I get the 
data into R.

Thanks,

Phillip J. Allen
Consulting Geochemist/Geologist
Lima Peru
e-mail: paallen at attglobal.net



Phillip,

How about this, which will generate a vertical barplot, a y axis from 0 
down to 40 meters and bar widths and colors for each segment varied:

from <- c(0, 1.2, 4.0, 4.2, 5.0, 25.0, 30.1)
to <- c(1.2, 4.0, 4.2, 5.0, 25, 30.1, 36.2)
intensity <- c(0, 1, 3, 2, 1, 0, 2)
barplot(intensity, width = -(to - from),
        space = 0, horiz = TRUE, ylim = c(-40, 0))
axis(2, las = 2, labels = c(40, 30, 20, 10, 0))
mtext(side = 2, text = "Hole Depth (m)", line = 3)


Hope that helps,

Marc Schwartz
**********************************************

It looks as though it should do: see in particular the
arguments height, width, and space, to the function
as described in help(barplot).

For example:
x0<-c(0, 1.2, 4.0, 4.2, 5.0, 25.0, 30.1)
x1<-c(1.2, 4.0, 4.2, 5.0, 25.0, 30.1, 36.2)
y<-c(0, 1, 3, 2, 1, 0, 2)
w<-x1-x0
y[y==0]<-0.001
barplot(height=y,width=w,space=0)

(the extra 0.001 gives a thickened baseline where y=0, to
avoid the impression that there is no bar at such points)

Ted.
******************************
original message

Hi all,



I am trying to make a bar plot of  observations along a line or 
specifically a drill hole with the bars widths representing the interval 
of the observation and the length of the bar the actual data.  My data 
is in the following format:



from(m)        to(m)        Intensity of silicification

0                    1.2            0

1.2                  4.0            1

4.0                   4.2            3

4.2                    5.0           2

5.0                    25            1

25.0                    30.1        0

30.1                    36.2         2

......





Is the barplot() function what I really want to use?



Thanks for any help.



Phillip J. Allen

Consulting Geochemist/Geologist

Lima Peru

e-mail: paallen at attglobal.net