I will try to explain my problem. There are 600 (global map)files (1440
sample * 720 lines)in two directories dir1 and dir2, which have the same
format ,byte,extend,etc. I computed the `bias` between two datasets
using the function and code given below as follows:
Function:
bias <-function(pred,obs,na.rm=TRUE){
mean((pred - obs), na.rm = na.rm)}
read files:
dir1 <- list.files("/donnees/notghi", "*.img",
full.names = TRUE)
dir2 <- list.files("/donnees/baieSt", "*.img",
full.names = TRUE)
for each x,y location, I would read it into a multi-dimensional array
with dimensions:
file_tot<-array(dim=c(1440,720,600,2))
Apply the code:
for(i in 1:length(dir1)){
file_tot[,,i,1] <- readBin(dir1[i], double(), size = 4 ,n = 1440*
720 , signed = T)
file_tot[,,i,2] <- readBin(dir2[i], double(), size = 4 ,n = 1440
* 720, signed = T)
}
calculate the `bias`:
result<-apply(file_tot,c(1,2),function(x){bias(x[,1],x[,2])})
This worked correctly and no problem with that.
now I want to modify the function and add third part(mod in the function
which should come from different data (dir3) other than dir1 and dir2):
function:
err<-function(pred,obs,mod,na.rm=TRUE){
sqrt(mean(((pred-obs)*(pred-mod)), na.rm = na.rm))}
read the files(note that now dir3 is added and files have the same
attributes):
dir1 <- list.files("/donnees/notghi", "*.img",
full.names = TRUE)
dir2 <- list.files("/donnees/baieSt", "*.img",
full.names = TRUE)
dir3 <- list.files("/donnees/modt", "*.img",
full.names = TRUE)
code:
I tried to do this,I put `3` instead of `2`:
file_tot<-array(dim=c(1440,720,600,3))## worked well
and then change this line accordingly:
from:
result<-apply(file_tot,c(1,2),function(x){bias(x[,1],x[,2])})
to :
result<-apply(file_tot,c(1,3),function(x){err(x[,1],x[,2],x[,3])})
## not 3 instead of 2 and I added x[,3]
Is that right?
This worked without errors but I checked the results and they were crap.
--
Amen Alyaari, UPMC
PhD student
Unit of Functional Ecology& Environmental Physics [EPHYSE]
National Institute of Agricultural Research [INRA].
71, Avenue Edouard Bourlaux
33140 Villenave d'Ornon
T?l?phone : +33(0) 5 57 12 24 27
Fax : +33 (0)5 57 12 24 20
FRANCE