[R-sig-Geo] replace values in spacetime (STFDF) object

[Roth, M.]

Hi,

thank you very much. But actually that is not exactly what I want to do. I want to select a specific time 
range and spatial points and manipulate the corresponding data. When I subset the dataframe I must do
the selection manually and that is not that nice.

Any idea how I could do this?
Cheers, Martin
________________________________________
From: Aman Verma [aman.verma at mcgill.ca]
Sent: Friday, March 11, 2011 7:16 PM
To: Roth, M.; r-sig-geo at r-project.org
Subject: RE: replace values in spacetime (STFDF) object

Hi Martin,
You put the brackets in the wrong place. You want to subset the dataframe, right, not the stfdf object, so:

stfdf at data$values[1] <- stfdf at data$values[1] + 1

would increase the "value" in the first row of the stfdf at data data frame.

stfdf at data[,1]

would get you the first column of the data frame. If you wanted to increase the whole column by one:

stfdf at data[,1] = stfdf at data[,1] + 1

aman

-----Original Message-----
From: r-sig-geo-bounces at r-project.org [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Roth, M.
Sent: March 11, 2011 10:00 AM
To: r-sig-geo at r-project.org
Subject: [R-sig-Geo] replace values in spacetime (STFDF) object

Hello,

I want to replace specific values in a STFDF object from the spacetime package.
As example consider the following stfdf object out of the vignette.

sp = cbind(x = c(0,0,1), y = c(0,1,1))
row.names(sp) = paste("point", 1:nrow(sp), sep="")
sp = SpatialPoints(sp)
time = xts(1:4, as.POSIXct("2010-08-05", tz = "GMT")+3600*(10:13))
m = c(10,20,30) # means for each of the 3 point locations
mydata = rnorm(length(sp)*length(time),mean=rep(m, 4))
IDs = paste("ID",1:length(mydata), sep = "_")
mydata = data.frame(values = signif(mydata,3), ID=IDs)
stfdf = STFDF(sp, time, mydata)

Now I want to do something like this:

stfdf[ , 1]@data$values <- stfdf[ , 1]@data$values + 1

I get the following error:

Error in stfdf[, 1]@data$values <- stfdf[, 1]@data$values + 1 :
  object of type 'S4' is not subsettable

Does anybody know how to do that in a correct way?
Thanks a lot,
Martin Roth
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