[R-sig-Geo] Changing values of raster pixels to NA

[Zia Uddin Ahmed]

You can try this:

files <- list.files(pattern='.tif$')
s <- stack(files)
names(s)
nl <- nlayers(s)

# Create Raster: values <1:
rc1<-function(x){
  ifelse(x>1.000,0,
    ifelse(x<=1.000,1,NA))}

r1.rc1<-calc(s,fun=rc1)
plot(r1.rc1)
r1<-r1.rc1*s
plot(r1)

# Create raster: values >=-1 and <=1
rc2<-function(x){
  ifelse(x< -1.000,0,
    ifelse(x>= -1.000,1,NA))}

r2.rc2<-calc(r1,fun=rc2)
r2<-r1*r2.rc2
plot(r2)

Zia
-----Original Message-----
From: r-sig-geo-bounces at r-project.org [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Carlos Vázquez
Sent: Tuesday, August 06, 2013 4:54 AM
To: r-sig-geo at r-project.org
Subject: [R-sig-Geo] Changing values of raster pixels to NA

Hi to all,
I have a problem using raster stacks in R.
I have a set of raster layers with pixel reliability information for NDVI with pixel values of 0,1,2, and 3 Since i am not interested in values 2 and 3, I want to change all 2 and 3 values in the raster layers to NA's I am using the following formula:

 NDVI[NDVI==3|NDVI==2]<-NA


It works fine for single rasters but when applying to a raster stack, it gives strange results, converting some 0 and 1 values to NA as well.

Any ideas of what might be wrong?
Any help will be appreciated.

Thanks in advance!

MSc. student

Carlos  Vázquez 
 		 	   		  
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