Hello all,
I would like to count the number of events that occur per minute for
some measurements I have taken. I would eventually like to look at
the sums of some of the measurements for the grouped events. I think
I am not understanding how to use the returned value from the trunc
function correctly, or I am having some sort of fundamental confusion
about the POSIX classes or how to use R to best accomplish this. I
was planning to try and create a factor from the truncated times then
use table(). I'm open to any advice or recommendations about packages
I can use.
What I have looks something like:
event.times event.values
1 2009-04-10 12:00:01 1.0378239
2 2009-04-10 12:00:02 0.1466919
3 2009-04-10 12:00:03 -1.5960907
4 2009-04-10 12:01:01 -0.1722599
5 2009-04-10 12:01:02 0.1030427
6 2009-04-10 12:02:02 0.5252564
7 2009-04-10 12:02:15 0.4551200
8 2009-04-10 12:03:20 -1.4248654
What I would like is something like:
Count
2009-04-10 12:00:00 3
2009-04-10 12:01:00 2
2009-04-10 12:02:00 2
2009-04-10 12:03:00 1
Here is some sample code of where I am at.
###################################################
# Create a mock of my data frame
start.time <- as.POSIXct("2009-04-10 12:00:00")
event.times <- start.time + c(1,2,3,61,62,122,135,200)
event.values <- rnorm(length(event.times))
et <- data.frame(event.times,event.values)
# This seems to give me part of what I want, the event times truncated
to the minute
trunc(event.times, units="mins")
# However, this line gives an error of "replacement has 9 rows, data has 8"
et$trunc.times <- trunc(event.times, units="mins")
###################################################
I'm also confused why this works as I would expect:
> factor(event.times)
However, the following fails with the error 'x' must be atomic for 'sort.list'
> factor(trunc(event.times,units="mins"))
Thanks in advance,
Jason
> sessionInfo()
R version 2.8.1 (2008-12-22)
x86_64-pc-linux-gnu
locale:
LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
