Counting the number of non-NA values per day
Try tempFun <- function(x) sum(!is.na(x)) nonZeros <- aggregate(pollution["pol"],format(pollution["date"],"%Y-%j"), FUN = tempFun)
--- On Wed, 12/8/09, Tim Chatterton <tim.chatterton at uwe.ac.uk> wrote:
From: Tim Chatterton <tim.chatterton at uwe.ac.uk>
Subject: [R] Counting the number of non-NA values per day
To: r-help at r-project.org
Received: Wednesday, 12 August, 2009, 3:26 AM
I have a long dataframe ("pollution")
that contains a column of hourly date information ("date")
and? a column of? pollution? measurements
("pol")
I have been happily calculating daily means and daily
maximums using the aggregate function
DMEANpollution =? aggregate(pollution["pol"],
format(pollution["date"],"%Y-%j"), mean, na.rm = TRUE)
DMAXpollution =? aggregate(pollution["pol"],
format(pollution["date"],"%Y-%j"), max, na.rm = TRUE)
However, I also need to count the number of valid
measurements for each day to check that the mean and max are
likely to be valid (for example I need at least 18 hourly
measurements to calculate a valid daily mean)
Try as I might I have not found a simple way of doing
this.
Can anybody help please?
Many thanks,
Tim.
--
__________________________________________ Dr Tim Chatterton Senior Research Fellow Air Quality Management Resource Centre Faculty of Environment and Technology University of the West of England Frenchay Campus Bristol BS16 1QY Tel: 0117 328 2929 Fax: 0117 328 3360 Email: Tim.Chatterton at uwe.ac.uk ______________________________________________ R-help at 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.