why there is no quarters?

Mon, Dec 16, 2013 5:12 AM

That will only work if your starting date happens to be the first day of the year:

x <- seq(as.Date("2001/1/1"), as.Date("2010/1/1"), "3 months")

[1] "2001-01-01" "2001-04-01" "2001-07-01" "2001-10-01" "2002-01-01"
[6] "2002-04-01"


Compare that to:

x2 <- seq(as.Date("2001/2/3"), as.Date("2010/1/1"), "3 months")

[1] "2001-02-03" "2001-05-03" "2001-08-03" "2001-11-03" "2002-02-03"
 [6] "2002-05-03" "2002-08-03" "2002-11-03" "2003-02-03" "2003-05-03"


The "3 months" is literally 3 months from the defined start date, not 3 months from the first of the year. So you are not going to get calendar quarter starting dates in that case.


On the other hand:

[1] 2001-01-01 2001-04-01 2001-07-01 2001-10-01 2002-01-01 2002-04-01
 [7] 2002-07-01 2002-10-01 2003-01-01 2003-04-01 2003-07-01 2003-10-01
[13] 2004-01-01 2004-04-01 2004-07-01 2004-10-01 2005-01-01 2005-04-01
[19] 2005-07-01 2005-10-01 2006-01-01 2006-04-01 2006-07-01 2006-10-01
[25] 2007-01-01 2007-04-01 2007-07-01 2007-10-01 2008-01-01 2008-04-01
[31] 2008-07-01 2008-10-01 2009-01-01 2009-04-01 2009-07-01 2009-10-01
36 Levels: 2001-01-01 2001-04-01 2001-07-01 2001-10-01 ... 2009-10-01


Regards,

Marc Schwartz

On Dec 16, 2013, at 6:35 AM, D?niel Kehl <kehld at ktk.pte.hu> wrote:

________________________________________
Felad?: r-help-bounces at r-project.org [r-help-bounces at r-project.org] ; meghatalmaz&#243;: Pancho Mulongeni [p.mulongeni at namibia.pharmaccess.org]
K?ldve: 2013. december 16. 13:05
To: 1248283536 at qq.com
Cc: r-help at r-project.org
T?rgy: Re: [R] why there is no quarters?

Hi,
I also would like to use quarters. I think a work around would be to just label each record in the dataframe by its quarter.
i.e. you add a factor called 'Quarter' with four levels (Q1 to Q4) for each row and you assign the level based on the month of the date.
You can easily do this with as.Date and as.character.

Pancho Mulongeni
Research Assistant
PharmAccess Foundation
1 Fouch? Street
Windhoek West
Windhoek
Namibia

Tel:   +264 61 419 000
Fax:  +264 61 419 001/2
Mob: +264 81 4456 286

why there is no quarters?

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