[R] column of dates into time series

[David Winsemius]

On Nov 29, 2009, at 7:52 AM, Linlin Yan wrote:

> There is no year() function. Maybe you can try format() instead.
>
> On Sun, Nov 29, 2009 at 8:44 PM, DispersionMap <frenchcr at btinternet.com 
> > wrote:
>>
>> i have a column of dates in this format:
>>
>> data[,"Raised.Date"] <- as.Date(data[,"Raised.Date"], "%d/%m/%Y");
>> data[1:10,"Raised.Date"]
>> [1] "2006-07-07" "2006-07-07" "2006-04-03" "2006-04-03" "2006-04-03"
>> "2006-04-03" "2006-04-03" "2006-04-03" "2006-04-03" "2006-04-03"
>>
>> I can turn them into months like this...
>>
>> Month<-months(data[,"Raised.Date"])
>> Month[1:10]
>> [1] "July"  "July"  "April" "April" "April" "April" "April" "April"  
>> "April"
>> "April"
>>
>>
>> But i also want to turn them into years (and also weeks later on),  
>> so tried
>> this...

library(chron)
?cut.dates

The argument breaks has several options including one of  c("days",  
"weeks", "months", "year")

 > dts <- Sys.Date() - 1:20

 > cut(dts, breaks="weeks")
  [1] 2009-11-23 2009-11-23 2009-11-23 2009-11-23 2009-11-23  
2009-11-23 2009-11-16 2009-11-16 2009-11-16 2009-11-16
[11] 2009-11-16 2009-11-16 2009-11-16 2009-11-09 2009-11-09 2009-11-09  
2009-11-09 2009-11-09 2009-11-09 2009-11-09
Levels: 2009-11-09 2009-11-16 2009-11-23

I was a bit puzzled when I tried cut.dates as the function which  
throws a function not found error.


>>
>> Year<-year(data[,"Raised.Date"])
>> Error: could not find function "year"
>


David Winsemius, MD
Heritage Laboratories
West Hartford, CT