R help - Jun 2008 - using contour() with x,y,z data?

Hello list,

I'm new to R and I have a problem :-)  Below is what my data file that looks
like.  I tried to import and contour this data by doing this:

   cv_data <-
read.table("cv_data.csv",sep=",",header=TRUE)
   attach(cv_data)
   contour(x,y,z)

I get the error "Error in contour.default(x,y,z) : increasing 'x',
and 'y'
values expected"  I can see that y is not increasing, but I don't know
how
to get this to work.

Thanks in advance for any help.

Bob
========================================================x,   y,   z
10, 0.1, 3
10, 0.2, 7
[snip]
10,1.0,5
20,0.1,12
20,0.2,4

	[[alternative HTML version deleted]]

Please **READ** ?contour. x and y are the location of grid lines, z must be
a matrix. Your data are **not** of that form.

Bert Gunter

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
Behalf Of Bob and Deb
Sent: Thursday, June 26, 2008 11:01 AM
To: r-help at r-project.org
Subject: [R] using contour() with x,y,z data?

Hello list,

I'm new to R and I have a problem :-)  Below is what my data file that looks
like.  I tried to import and contour this data by doing this:

   cv_data <-
read.table("cv_data.csv",sep=",",header=TRUE)
   attach(cv_data)
   contour(x,y,z)

I get the error "Error in contour.default(x,y,z) : increasing 'x',
and 'y'
values expected"  I can see that y is not increasing, but I don't know
how
to get this to work.

Thanks in advance for any help.

Bob
========================================================x,   y,   z
10, 0.1, 3
10, 0.2, 7
[snip]
10,1.0,5
20,0.1,12
20,0.2,4

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

"Bob and Deb" <bobdebm at gmail.com> writes:
> I'm new to R and I have a problem :-)  Below is what my data file that
looks
> like.  I tried to import and contour this data by doing this:
>
>    cv_data <-
read.table("cv_data.csv",sep=",",header=TRUE)
>    attach(cv_data)
>    contour(x,y,z)
>
> I get the error "Error in contour.default(x,y,z) : increasing
'x', and 'y'
> values expected"  I can see that y is not increasing, but I don't
know how
> to get this to work.
All of your arguments to contour are wrong. x and y are the locations of
the gridlines for the figure (and are not required), and z is a matrix
of values, not a single vector. See ?contour for the details and
examples.

I'm sure there is a better way to do this, but when I have data in the
format you do:

x   y     z
10, 0.1,  3
10, 0.2,  7
[snip]
10, 1.0,  5
20, 0.1, 12
20, 0.2,  4

I use the following function to convert it to the proper format:

image.maker <- function(coords, value){
  N <- length(unique(coords[,1]))
  image.out <- matrix(NA, nrow = N, ncol = N)
  coords[,1] <- as.numeric(factor(coords[,1]))
  coords[,2] <- as.numeric(factor(coords[,2]))
  for (i in 1:nrow(coords))
    image.out[coords[i,1], coords[i,2]] <- value[i]
  return(image.out)
}


my.image <- image.maker(cv_data[,c("x", "y")], cv_data$z)
contour(my.image)

HTH,

Tyler

-- 
Power corrupts. PowerPoint corrupts absolutely.
                                       --Edward Tufte

http://www.wired.com/wired/archive/11.09/ppt2.html

Hi

you probably want to look to interp from arima package

Petr Pikal
petr.pikal at precheza.cz
724008364, 581252140, 581252257


r-help-bounces at r-project.org napsal dne 26.06.2008 20:00:48:
> Hello list,
> 
> I'm new to R and I have a problem :-)  Below is what my data file that 
looks
> like.  I tried to import and contour this data by doing this:
> 
>    cv_data <-
read.table("cv_data.csv",sep=",",header=TRUE)
>    attach(cv_data)
>    contour(x,y,z)
> 
> I get the error "Error in contour.default(x,y,z) : increasing
'x', and
'y'
> values expected"  I can see that y is not increasing, but I don't
know
how
> to get this to work.
> 
> Thanks in advance for any help.
> 
> Bob
> ========================================================> x,   y,   z
> 10, 0.1, 3
> 10, 0.2, 7
> [snip]
> 10,1.0,5
> 20,0.1,12
> 20,0.2,4
> 
>    [[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.