[R] Counting dates in arbitrary ranges

Simon Kiss simonjkiss at yahoo.ca
Tue Jan 18 08:16:37 CET 2011

Dear Colleagues,
I have a data set that looks as below. I'd like to count the number of dates in a series of arbitrary ranges (breaks) i.e. not pre-defined breaks such as months, quarters or years. table(format()) produces ideally formatted output, but table() does not appear to accept arbitrary ranges.
I also tried converting the dates to numeric and using histogram to try to get the data, but that doesn't work either.  Cut appears to accept an arbitrary range, but I could only get it to produce NAs.

Any suggestions? Yours, Simon Kiss

mydata<-list(x=seq(as.Date("2007-05-01"), as.Date("2009-09-10"),"days"), y=seq(as.Date("2007-06-16"), as.Date("2009-11-12"),"days"))
table(format(mydata[[1]], "%Y")) 
t_1<-hist(as.numeric(mydata[[1]], breaks=c("14056", "14421")))$counts
cut(mydata[[1]], breaks=c(as.Date("2008-06-26"), ("2009=06-26")))

Simon J. Kiss, PhD
Assistant Professor, Wilfrid Laurier University
73 George Street
Brantford, Ontario, Canada
N3T 2C9
Cell: +1 519 761 7606

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