[R-sig-Finance] Problems subsetting zoo objects

[icosa atropa]

Hello,

After 6 months of using both the its and the zoo packages, I've grown
fond of the zoo package, but I still struggle with subsetting
zoo objects.

I'm trying to remove outliers from my records by setting them to NA; I
can do some dataframe-type subsetting with "its" objects, but I'm
still confused about zoo's rules.

###An example -------------------
require(zoo); require(its)
my.data = data.frame(depth=c(5, 6, 30), temp=c(20, 21, 100))
my.index = as.POSIXct(c("1999-02-10", "1999-02-11", "1999-02-12"))
my.zoo = zoo(my.data, order.by=my.index)
my.its = as.its(my.zoo)

#Questions
#1 -   Not supposed to work?
my.zoo$depth  #NULL
my.its$zoo   #NULL
dynlm(depth ~ temp, data=my.zoo)  #works
my.data$depth  # works

#2 - I expected the following line to return values
my.zoo[my.zoo[,1] > 10]    # returns column names but no values
my.zoo[my.zoo[,1] > 10]  = NA   # Still, this _does_ work
my.its[my.its[,1] > 10 ]               #  And this returns values

my.zoo = zoo(my.data, order.by=my.index)  # reset my.zoo

#3 - I try to isolate my confusion:
my.zoo[c(T,F,F),1]  == 5 # True
my.zoo[c(T,F,F),2] == 20 # True
my.zoo[c(T,F,F),1:2]  == 5 # True.  Why not ==c(5,20)?
#i.e.
my.zoo[c(T,F,F),1:2] == my.zoo[c(T,F,F),c(T,F)]   #True
my.zoo[c(T,F,F),1:2] == my.zoo[c(T,F,F),c(F,T)]  #False
my.zoo[c(F,F,T), c(T,F)] ==  my.zoo[c(F,F,T), c(T,T)]  #True

#End of Example---------------------------------

I'd greatly appreciate any insights or suggests.
Thanks in advance,

Christian Gunning
Masters Student
University of New Mexico
Dept of Water Resources