[R] Repeating grey scale in graph?

[Sander Oom]

Aaaah...the inner workings of R! Now I also see why the colours are not 
only repeated, but also 'wrongly' allocated to the facets! Very clear 
example!

Indeed a warning or error would have been more helpful!

Cheers,

Sander.

PS: I hope that after all this, I can still convince the creator of the 
original data that it is a good idea to plot his graphs in R instead of 
excel.  ;-)


Duncan Murdoch wrote:

>On Wed, 16 Feb 2005 15:44:00 +0200, Sander Oom
><slist at oomvanlieshout.net> wrote :
>
>  
>
>>Thanks Peter!
>>
>>Of course I only have (nx-1)(ny-1) facets in a x*y plot!
>>
>>The help page line:
>>...
>>col 	the color(s) of the surface facets. Transparent colours are 
>>ignored. This is recycled to the (nx-1)(ny-1) facets.
>>...
>>just did not ring a bell.
>>
>>In fact, it is still not clear to me why it recycles the ramp even 
>>though it has a surplus of colours (grey levels)! Why not just ignore 
>>the surplus colours?
>>    
>>
>
>Your z array is 6 by 7.  Your cols will be mapped to a 5 by 6 array.
>They don't look like an array, because the grey() function stripped
>off the dimension attribute.
>
>The problem is that if you pass the entries from a 6 by 7 array to
>something that expects the entries from a 5 by 6 array, you get things
>in the wrong order.   You see the same effect here:
>
>  
>
>>rownum <- as.vector(row(matrix(NA, 6, 7)))
>>matrix(rownum, 6, 7)
>>    
>>
>     [,1] [,2] [,3] [,4] [,5] [,6] [,7]
>[1,]    1    1    1    1    1    1    1
>[2,]    2    2    2    2    2    2    2
>[3,]    3    3    3    3    3    3    3
>[4,]    4    4    4    4    4    4    4
>[5,]    5    5    5    5    5    5    5
>[6,]    6    6    6    6    6    6    6
>  
>
>>matrix(rownum, 5, 6)
>>    
>>
>     [,1] [,2] [,3] [,4] [,5] [,6]
>[1,]    1    6    5    4    3    2
>[2,]    2    1    6    5    4    3
>[3,]    3    2    1    6    5    4
>[4,]    4    3    2    1    6    5
>[5,]    5    4    3    2    1    6
>Warning message:
>data length [42] is not a sub-multiple or multiple of the number of
>rows [5] in matrix 
>
>except that in this case you get a warning about the wrong length;
>persp doesn't give you the warning.  Maybe it should?
>
>Duncan Murdoch
>
>
>  
>

-- 
---------------------------------------------------------
Dr. Sander P. Oom
Animal, Plant and Environmental Sciences
University of the Witwatersrand
Private Bag 3
Wits 2050
South Africa

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