library(gdxrrw)

data1 <- rgdx("allData.gdx", list(name="x", field="all"))
dataX <- rgdx("justX.gdx", list(name="x", field="all"))
str(data1)
str(dataX)

# important facts: "the UEL universe" is all the UELs available at one
# time or to one environment. With GDX, the universe is all the UELs in the GDX.
# To see it, do from a command prompt:
# gdxdump justX.gdx uelTable=theUniverse
# the * is used to represent the universe

# dataX contains limited domain information, so we get the data back as
# if it were declared over the universe, i.e. S(*,*)
# if we want it another way, we can provide a UEL filter.
# We can call this method 2:

filter2 <- list(c('a','b','c'),c('1','2','3'))  
data2 <- rgdx("justX.gdx", list(name="x", field="all", uels=filter2))


# method 2 is pretty lame: we would not want to bake the uel filter into the
# script itself.  We can read the UELS from a GDX file, for example:


s <- rgdx('allData.gdx',list(name='s',compress=T))
suels <- s$uels[[1]]
t <- rgdx('allData.gdx',list(name='t',compress=T))
tuels <- t$uels[[1]]
filter3 <- list(suels,tuels)  
data3 <- rgdx("justX.gdx", list(name="x", field="all", uels=filter3))