[R] density plot - beginner's question
kjetil brinchmann halvorsen
kjetil at entelnet.bo
Tue Jan 14 04:09:05 CET 2003
On 13 Jan 2003 at 18:22, Saurav Pathak wrote:
> 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.
> 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.
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