The simplest way is probably to generate them as the columns of a
matrix. Let's suppose you have data from Jan 1991 up to Mar 2008.
> X <- outer(rep(month.abb, length = 16*12+3), month.abb, "==") + 0
> ## the "+ 0" will convert logical to numeric
> dim(X)
[1] 195 12
> dimnames(X)[[2]] <- month.abb
> head(X)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
[1,] 1 0 0 0 0 0 0 0 0 0 0 0
[2,] 0 1 0 0 0 0 0 0 0 0 0 0
[3,] 0 0 1 0 0 0 0 0 0 0 0 0
[4,] 0 0 0 1 0 0 0 0 0 0 0 0
[5,] 0 0 0 0 1 0 0 0 0 0 0 0
[6,] 0 0 0 0 0 1 0 0 0 0 0 0
>
To get the July indicators, use X[, "Jul"], &c
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-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Megh Dal
Sent: Friday, 25 April 2008 5:40 PM
To: [EMAIL PROTECTED]
Subject: [R] Constructing dummy variables for months for a time series
object
I have a TS of monthly observations.
head(data4)
1991(1) 1991(2) 1991(3) 1991(4) 1991(5) 1991(6)
12.00864 11.94203 11.98386 12.01900 12.19226 12.15488
Now I want to make 11 dummy variables indicating months. Therefore I
did followings :
For Jan :
rep(c(rep(0,0), 1, rep(0, 11)), 17)
For Feb :
rep(c(rep(0,1), 1, rep(0, 10)), 17)
........ and so on
But my question is there any way to aumate this? Or I have to do the
above thing for all 11 months?
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