[R] using its to import time series data with uneven dates

[Gabor Grothendieck]

On 7/12/05, Sheri Conner Gausepohl <sheri at atmos.colostate.edu> wrote:
> Good day:
> 
> I am trying to use
> readcsvIts("nwr_data_qc.txt",informat=its.format("%Y%m%d%h%M
> %Y"),header=TRUE,sep="",skip=0,row.names=NULL,as.is=TRUE,dec=".")
> 
> to read in a file (nwr_data_qc.txt)  that looks like this:
> 
> Time         Y      M   D  H   Min    CO2
> 2000.18790   2000.  3.  9. 18. 30.    373.60
> 2000.20156   2000.  3. 14. 18. 30.    373.34
> 2000.22609   2000.  3. 23. 18.  0.    373.01
> 
> and  R returns this:
> 
>         Y  M  D  H Min    CO2
> <NA> 2000  3  9 18  30 373.60
> <NA> 2000  3 14 18  30 373.34
> <NA> 2000  3 23 18   0 373.01
> 
> I have tried every format option on the help page.  How can I read in
> my decimal dates (e.g., 2000.18790)?
> 
> Note that these data (CO2) are irregularly spaced in time (Time).
> 
> Ultimately I would like to fit a trigonometric polynomial (first
> harmonic) to these data in order to smooth them and obtain values
> between measurements.  Any suggestions you can provide on how to do
> this would be much appreciated.
> 
> Thank you for your help.
> 
> Sheri
> 
> Sheri L. Conner Gausepohl
> Graduate Research Assistant
> Department of Atmospheric Science
> Colorado State University

Try this:

library(its)
dd <- read.table(myfile, header = TRUE)
tt <- paste(dd$Y, "-", dd$M, "-", dd$D, " ", dd$H, ":", dd$Min, sep = "")
co2 <- its(dd$CO2, as.POSIXct(tt))
co2 # display co2