Re: simple question

[David L Lorenz <lorenz@usgs.gov>]

Eric,
  A combination of the quarters()
and years() functions should work for you. Each would create a factor,
but if you extract the integer value, you could produce the desired sequence
as months + (years - 1) * 4.
Dave

Eric yang <yang_eric9@yahoo.com>
Sent by: s-news-owner@lists.biostat.wustl.edu

03/24/2006 10:18 AM

To	s-news@wubios.wustl.edu
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Subject	[S] simple question

Dear all,
 
Can someone help me with a very simple
question. Suppose I have the dates
 
 
my.dates <- c("03/01/05",
"04/01/05", "05/01/05", "06/01/05", "07/01/05",
"08/01/05", "09/01/05", "10/01/05", "11/01/05",
"12/01/05", "01/01/06", "02/01/06", "03/01/06",
"04/01/06", "05/01/06", "06/01/06", "07/01/06",
"08/01/06", "09/01/06", "10/01/06", "11/01/06")
 
 
and I want to split the my.dates into a
sequence related to the quarterly period, i.e. grouping into ("01",
"02", "03"), ("04", "05", "06"),
("07", "08", "09") and ("10", "11",
"12")
 
to give
> my.sequence
[1] 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7
7 8 8
Thanks in advance for any help.
 
Regards
Eric

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