Using R cut function on dates

Question

I have a dataframe giving attendances at sports events

Crowd    matchDate
2345      1993-01-26
4567      1993-08-01
8888      1994-03-02
1298      1994-11-07         


        

Answer 1

An example of my comment.

x <- as.Date(1:1000, origin = "2000-01-01")
x <- cut(x, breaks = "quarter") 

And then relabel as you please, if necessary.

labs <- paste(substr(levels(x),1,4), "/", 1:4, sep="")
x <- factor(x, labels = labs)

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?cut.POSIXct

breaks
a vector of cut points or number giving the number of intervals which x is to be cut into or an interval specification, one of "sec", "min", "hour", "day", "DSTday", "week", "month", "quarter" or "year", optionally preceded by an integer and a space, or followed by "s". (For "Date" objects only interval specifications using "day", "week", "month", "quarter" and "year" are allowed.)

Answer 2

If your question is more related to how you automatically generate the breaks and labels, maybe this will help

DF <- data.frame(matchDate = as.POSIXct(as.Date(sample(5000,100,replace=TRUE), origin="1993-01-01")))

years <- 1992:2011
DF$season <- cut(DF$matchDate, 
  breaks=as.POSIXct(paste(years,"-08-01",sep="")),
  labels=paste(years[-length(years)],years[-length(years)]+1,sep="/"))