Not at a computer to test this but perhaps rle(is.na(x))
might help. Michael On Feb 12, 2012, at 7:36 PM, "Durant, James T. (ATSDR/DTEM/PRMSB)" <h...@cdc.gov> wrote: > Hi - > > I am trying to find and describe missing data in a time series. For instance, > in the library openair, there is a data frame called "mydata": > library(openair) > head(mydata) > > date ws wd nox no2 o3 pm10 so2 co pm25 > 1 1998-01-01 00:00:00 0.60 280 285 39 1 29 4.7225 3.3725 NA > 2 1998-01-01 01:00:00 2.16 230 NA NA NA 37 NA NA NA > 3 1998-01-01 02:00:00 2.76 190 NA NA 3 34 6.8300 9.6025 NA > 4 1998-01-01 03:00:00 2.16 170 493 52 3 35 7.6625 10.2175 NA > 5 1998-01-01 04:00:00 2.40 180 468 78 2 34 8.0700 8.9125 NA > 6 1998-01-01 05:00:00 3.00 190 264 42 0 16 5.5050 3.0525 NA > > > So for example, I would like to be able to detect for pm25, I would like to > be able to detect that there are NA's starting at 1998-01-01 0:00:00 and runs > for 2887 hourly observations. Then I would be able to know that there is an > NA at 2910 and so on. The key information I am looking for is when the NA's > start and their length. The closest thing I can use that I know about is > timePlot in the openair package with statistic="frequency" but it only gives > monthly summary data, and does not tell me if the missing data are clumped > together or are dispersed. > > VR > > Jim > > > James T. Durant, MSPH CIH > Emergency Response Coordinator > US Agency for Toxic Substances and Disease Registry > Atlanta, GA 30341 > 770-378-1695 > > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. ______________________________________________ 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.
