[R-sig-Geo] several 'if' conditions with 'apply'

[Michal Gallay]

Dear R Users,

I am trying to apply a function to each cell of a data frame, which can 
contain NAs, or values between -360 to +360.

The function should test if each value fullfils one of the conditions and 
converts this value accordingly.
 
As can be seen from the outputs it seems that only the last 'if' condition 
in the 'else' block is applied so that only some values were correctly 
transformed.

I cannot really get my head around this, what I am doing wrong. I tried 
several versions. I feel I am missing something very simple but I just 
can't see it.

Would some be able to help please?

Thank you very much for any directions of how to approach it.

Michal

> resid
       a   b  c   d    e    f
7325 270  10  0   4    7  107
7326  NA  NA NA  NA   NA   NA
7327  NA  NA NA  NA   NA   NA
7328 212 330  0 321   -1   -1
7329   3   5  0  22 -292 -215
7330 353 345  0 317  359  126
> 
> my.fun <- function(xx)
+  {
+ 
+   if(is.na(xx)) # if the value at xx is NA, let it be otherwise ...
+    {
+     xx=xx
+    } else 
+    {
+ if(xx < 180 & xx > 0 || xx == 180 || xx == -180 || xx ==0) xx=abs(xx);
+ if(xx > -180 & xx <0) xx=xx;
+ if(xx > 180 & xx < 360) xx=xx-360;
+ if(xx < -180 & xx > -360) xx=xx+360
+    }
+  }
> 
> 
> bb <- apply(resid, c(1,2), my.fun)
> bb
     a    b    c    d    e    f   
7325 NULL NULL NULL NULL NULL NULL
7326 NA   NA   NA   NA   NA   NA  
7327 NA   NA   NA   NA   NA   NA  
7328 NULL NULL NULL NULL NULL NULL
7329 NULL NULL NULL NULL 68   145 
7330 NULL NULL NULL NULL NULL NULL
> 

PS:
> sessionInfo()
R version 2.6.2 (2008-02-08) 
i386-pc-mingw32 

locale: 
LC_COLLATE=Slovak_Slovakia.1250;LC_CTYPE=Slovak_Slovakia.1250;LC_MONETARY=Slovak_Slovakia.1250;LC_NUMERIC=C;LC_TIME=Slovak_Slovakia.1250 
attached base packages: [1] stats graphics grDevices utils datasets methods 
base other attached packages: [1] circular_0.3-8 boot_1.2-31 rgdal_0.5-24 
sp_0.9-23 loaded via a namespace (and not attached): [1] grid_2.6.2 
lattice_0.17-6 rcompgen_0.1-17 tools_2.6.2
> 

-- 
Michal Gallay

Postgraduate Research Student
School of Geography, Archaeology and Palaeoecology
Queen's University
Belfast BT7 1NN
Northern Ireland

Tel: +44(0)2890 273929
Fax: +44(0)2890 973212
email: mgallay01 at qub.ac.uk
www: www.qub.ac.uk/geog