Re: Working with Tower Data in R Question

Skip to first unread message

john brzustowski

Jun 16, 2016, 9:21:03 PM6/16/16
to Howell, Jessica, Motus Wildlife Tracking System
Hi Jessica,

On Thu, Jun 16, 2016, at 16:23, Howell, Jessica wrote:

> I used a test tag (#401) at each of the towers when we visited on
> Monday, to look at how signal strength and detection on different
> antennae changed as I walked a short distance from the tower at each
> of the cardinal and primary intercardinal directions. Now I have
> the all tags RDS file from Reed W in R, subsetted just the data from
> the test tag 401, and I am trying to subset antenna 1 so I can plot
> time and signal strength of all observations of 401 on this antenna.
> R says column antenna is a factor, but when I try to subset it as a
> factor it gives a data frame with all variables but 0 observations
> (See R code I used below). Would this be something you could help
> me with? No worries if not.
> x401<-subset(x, id == 401) #subsetting Reed W data (x) to only observations of tag 401
> ant1<-subset(x401, ant == 1) #subsetting antenna 1, have tried both with and without parentheses

[I'm taking the liberty of replying to the motus-wts google group]

Factors have 'levels' (i.e. values) that work like strings, rather than numbers.

So this:

ant1 <- subset(x401, ant == "1 ")

is probably what you want. And yes, for no reason that I can remember,
there's a space character after the 1; we'll probably change that at some point.

You can get the possible values of a factor by doing, e.g.:


from which you would see the "1 " as one possible value.

We provide the antenna as a factor to allow for the occasional non-numeric
antenna name in data from Lotek receivers (e.g. "AH0").

Reply all
Reply to author
0 new messages