R help - Jun 2005 - DEM calculation

Hello R-World,

i am trying to calculate data for a DEM (Digital Elavation Model) which i
also want to plot in R. i have the coordinates for the lower left corner
which look something like this:

x<-42,2
y<-50,5

besides i have the cellsize of the grid, which is:

z<-1,1

what i do is to calculate the corrdinates of the cells to the right and top,
what i can do by specifying the number of rows and columns. these are
j<-1:805 (columns)
i<-1:616 (rows)

well, to calculate them seperatly is easy:

r<-x+(i-1)*z
h<-y+(j-1)*z

but i can't get it straight how to create a data frame with two rows, one
for the x- the other for the y-coordinate. The problem is, that lots of
values have to be repeated as every  first row x-coordinate has the same
y-coordinate and so on.

finally it should look like this:

x            y
42,2   50,5
43,3   50,5
44,4   50,5
45,5   50,5
 .         .
 .         .
42,2   51,5
43,3   51,5
44,3   51,5

any suggestion? thanks in advance, Lars Claussen

You can use ??expand.grid'

?? expand.grid(x=seq(42.2,45.2,by=1),y=seq(50.5,51.5,by=1))
     x    y
1 42.2 50.5
2 43.2 50.5
3 44.2 50.5
4 45.2 50.5
5 42.2 51.5
6 43.2 51.5
7 44.2 51.5
8 45.2 51.5


Eric

Eric Lecoutre
UCL /  Institut de Statistique
Voie du Roman Pays, 20
1348 Louvain-la-Neuve
Belgium

tel: (+32)(0)10473050
lecoutre at stat.ucl.ac.be
http://www.stat.ucl.ac.be/ISpersonnel/lecoutre

If the statistics are boring, then you've got the wrong numbers. -Edward
Tufte   

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Lars Claussen
> Sent: jeudi 2 juin 2005 10:56
> To: R-help at stat.math.ethz.ch
> Subject: [R] DEM calculation
> 
> 
> Hello R-World,
> 
> i am trying to calculate data for a DEM (Digital Elavation 
> Model) which i also want to plot in R. i have the coordinates 
> for the lower left corner which look something like this:
> 
> x<-42,2
> y<-50,5
> 
> besides i have the cellsize of the grid, which is:
> 
> z<-1,1
> 
> what i do is to calculate the corrdinates of the cells to the 
> right and top, what i can do by specifying the number of rows 
> and columns. these are j<-1:805 (columns) i<-1:616 (rows)
> 
> well, to calculate them seperatly is easy:
> 
> r<-x+(i-1)*z
> h<-y+(j-1)*z
> 
> but i can't get it straight how to create a data frame with 
> two rows, one for the x- the other for the y-coordinate. The 
> problem is, that lots of values have to be repeated as every  
> first row x-coordinate has the same y-coordinate and so on.
> 
> finally it should look like this:
> 
> x            y
> 42,2   50,5
> 43,3   50,5
> 44,4   50,5
> 45,5   50,5
>  .         .
>  .         .
> 42,2   51,5
> 43,3   51,5
> 44,3   51,5
> 
> any suggestion? thanks in advance, Lars Claussen
> 
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