[R] density plot - beginner's question
Henrik Bengtsson
hb at maths.lth.se
Tue Jan 14 04:23:03 CET 2003
> -----Original Message-----
> From: r-help-admin at stat.math.ethz.ch
> [mailto:r-help-admin at stat.math.ethz.ch] On Behalf Of kjetil
> brinchmann halvorsen
> Sent: den 14 januari 2003 14:08
> To: r-help at stat.math.ethz.ch; Saurav Pathak
> Subject: Re: [R] density plot - beginner's question
>
>
> On 13 Jan 2003 at 18:22, Saurav Pathak wrote:
>
> > Hi,
> >
> > I am trying to plot densities given on a two dimensional grid. My
> > data is in the an external file, and is arranged in three
> columns: x,
> > y, density
> >
> > how may i get a plot of this? i would like to get (1) a three
> > dimensional plot and (2) a color coded two dimensional plot.
> >
> > I have tried using
> >
> > image(x, y, density)
>
> You have here x, y, density vectors of the same length, which is not
> what image expects. The help page for image tells you that x and y
> should be vectors (each in ascending order), and z a matrix
> with dimensions length(x) and length(y). See the example on
> the help page
> for image. If your data are not a rectangular grid, you must probably
> interpolate before you can use image.
The code example at http://www.maths.lth.se/help/R/image/ might also
shine some light on the image() function, especially on how the coloring
is done.
Henrik Bengtsson
> Kjetil Halvorsen
>
>
> >
> > but i am asked to put the data in ascending order. i am
> not sure how
> > i may put grid points in an ascending order.
> >
> > I would also like to know if i could use any other function, other
> > than image.
> >
> > thank you in advance.
> >
> > --
> > saurav
> >
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