[R] Creating quarterly data

[Allan Engelhardt]

One approach:

d <- data.frame(x1=c(2,3,4,1,5,8), x2=c(4,1,6,4,6,5), time=1:6)
d$quarter <- (d$time-1) %/% 4  #  Or whatever your logic is
aggregate(cbind(x1,x2) ~ quarter, data = d, sum)
#   quarter x1 x2
# 1       0 10 15
# 2       1 13 11


Hope this helps

Allan


On 28/06/10 13:23, Thomas Jensen wrote:
> Dear R Experts,
>
> I have data in the following format
>
> x1    x2    time
> 2    4    1
> 3    1    2
> 4    6    3
> 1    4    4
> 5    6    5
> 8    5    6
> .    .    .
> .    .    .
> .    .    .
> 1    5    399
> 3    4    400
>
> Time represents each month which simply has a number from 1 to 400 
> (i.e. the data covers 400 months). I would like to somehow create two 
> new variables which counts x1 and x2 as quarterly data in stead of 
> monthly. Like this:
>
> x1    x1    Quarter
> 10    12    1
> 12    15    2
> .    .    .
> .    .    .
> .    .    .
> 23    21    100
>
> Can any one tell me how this can be done in R?
>
> With kind regards,
> Thomas Jensen
>
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