R help - May 2010 - sum of certain length

Hi r-users,
 
I have this data below.  I would like to obtain the weekly rainfall sum.  That
is I would like to find sum for day 1 to day 7, day 8 - day15, and so on.
   year month day rain
1  1922     1   1  0.0
2  1922     1   2  0.0
3  1922     1   3  0.0
4  1922     1   4  0.0
5  1922     1   5  0.0
6  1922     1   6  0.0
7  1922     1   7  0.0
8  1922     1   8  6.6
9  1922     1   9  1.5
10 1922     1  10  0.0
11 1922     1  11  0.0
12 1922     1  12  4.8
13 1922     1  13 14.7
14 1922     1  14  0.0
15 1922     1  15  0.0
16 1922     1  16  0.0
17 1922     1  17  0.0
18 1922     1  18  0.0
19 1922     1  19  0.0
20 1922     1  20  0.8
21 1922     1  21  0.0
22 1922     1  22  0.0
23 1922     1  23  0.0
24 1922     1  24  0.0
25 1922     1  25  0.0
26 1922     1  26  0.0
27 1922     1  27  0.0
28 1922     1  28  0.0
29 1922     1  29  0.0
30 1922     1  30  0.0
31 1922     1  31  0.0
32 1922     2   1  0.0
33 1922     2   2  0.0
34 1922     2   3  0.0
35 1922     2   4  0.0
36 1922     2   5  0.0
37 1922     2   6  0.0
38 1922     2   7  0.0
39 1922     2   8  0.0
40 1922     2   9  0.0

Thank you.


      
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This is one way to do it.  Suppose your data is in the file
"rainfall.txt", as set out below.  Then
> dat <- read.table("rainfall.txt", header = TRUE)
> dat <- within(dat, {
+   date <- as.Date(paste(year, month, day, sep="-"))
+   week <- factor(as.numeric(date - date[1]) %/% 7)
+ })
> wRain <- with(dat, tapply(rain, week, sum))
> wRain
   0    1    2    3    4    5 
 0.0 27.6  0.8  0.0  0.0  0.0 
> 
 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Roslina Zakaria
Sent: Monday, 24 May 2010 10:09 AM
To: r-help at r-project.org
Subject: [R] sum of certain length

Hi r-users,
?
I have this data below.? I would like to obtain?the weekly?rainfall sum.? That
is I would like to find sum for day 1 to day 7, day 8 - day15, and so on.
?? year month day rain
1? 1922???? 1?? 1? 0.0
2? 1922???? 1?? 2? 0.0
3? 1922???? 1?? 3? 0.0
4? 1922???? 1?? 4? 0.0
5? 1922???? 1?? 5? 0.0
6? 1922???? 1?? 6? 0.0
7? 1922???? 1?? 7? 0.0
8? 1922???? 1?? 8? 6.6
9? 1922???? 1?? 9? 1.5
10 1922???? 1? 10? 0.0
11 1922???? 1? 11? 0.0
12 1922???? 1? 12? 4.8
13 1922???? 1? 13 14.7
14 1922???? 1? 14? 0.0
15 1922???? 1? 15? 0.0
16 1922???? 1? 16? 0.0
17 1922???? 1? 17? 0.0
18 1922???? 1? 18? 0.0
19 1922???? 1? 19? 0.0
20 1922???? 1? 20? 0.8
21 1922???? 1? 21? 0.0
22 1922???? 1? 22? 0.0
23 1922???? 1? 23? 0.0
24 1922???? 1? 24? 0.0
25 1922???? 1? 25? 0.0
26 1922???? 1? 26? 0.0
27 1922???? 1? 27? 0.0
28 1922???? 1? 28? 0.0
29 1922???? 1? 29? 0.0
30 1922???? 1? 30? 0.0
31 1922???? 1? 31? 0.0
32 1922???? 2?? 1? 0.0
33 1922???? 2?? 2? 0.0
34 1922???? 2?? 3? 0.0
35 1922???? 2?? 4? 0.0
36 1922???? 2?? 5? 0.0
37 1922???? 2?? 6? 0.0
38 1922???? 2?? 7? 0.0
39 1922???? 2?? 8? 0.0
40 1922???? 2?? 9? 0.0

Thank you.


      
	[[alternative HTML version deleted]]

If the days are consecutive with no missing rows then the dates don't
need to be calculated and it could be represented as a ts series with
a frequency of 7.  Just aggregate it down to a frequency of 1:

   rain <- ts(dat$rain, freq = 7)
   aggregate(rain, 1)

If there are missing rows (or even there are none missing) you could
use zoo.  This time lets use dates:

   library(zoo)
   rain <- with(dat, zoo(rain, as.Date(paste(year, month, day, sep =
"-"))))
   week <- 7 * (as.numeric(time(rain)-start(rain)) %/% 7) + start(rain) + 6
   aggregate(rain, week)

Each point in the aggregated series is associated with the date of the
end of its week.


On Sun, May 23, 2010 at 8:09 PM, Roslina Zakaria <zroslina at yahoo.com>
wrote:
> Hi r-users,
>
> I have this data below.? I would like to obtain?the weekly?rainfall sum.?
That is I would like to find sum for day 1 to day 7, day 8 - day15, and so on.
> ?? year month day rain
> 1? 1922???? 1?? 1? 0.0
> 2? 1922???? 1?? 2? 0.0
> 3? 1922???? 1?? 3? 0.0
> 4? 1922???? 1?? 4? 0.0
> 5? 1922???? 1?? 5? 0.0
> 6? 1922???? 1?? 6? 0.0
> 7? 1922???? 1?? 7? 0.0
> 8? 1922???? 1?? 8? 6.6
> 9? 1922???? 1?? 9? 1.5
> 10 1922???? 1? 10? 0.0
> 11 1922???? 1? 11? 0.0
> 12 1922???? 1? 12? 4.8
> 13 1922???? 1? 13 14.7
> 14 1922???? 1? 14? 0.0
> 15 1922???? 1? 15? 0.0
> 16 1922???? 1? 16? 0.0
> 17 1922???? 1? 17? 0.0
> 18 1922???? 1? 18? 0.0
> 19 1922???? 1? 19? 0.0
> 20 1922???? 1? 20? 0.8
> 21 1922???? 1? 21? 0.0
> 22 1922???? 1? 22? 0.0
> 23 1922???? 1? 23? 0.0
> 24 1922???? 1? 24? 0.0
> 25 1922???? 1? 25? 0.0
> 26 1922???? 1? 26? 0.0
> 27 1922???? 1? 27? 0.0
> 28 1922???? 1? 28? 0.0
> 29 1922???? 1? 29? 0.0
> 30 1922???? 1? 30? 0.0
> 31 1922???? 1? 31? 0.0
> 32 1922???? 2?? 1? 0.0
> 33 1922???? 2?? 2? 0.0
> 34 1922???? 2?? 3? 0.0
> 35 1922???? 2?? 4? 0.0
> 36 1922???? 2?? 5? 0.0
> 37 1922???? 2?? 6? 0.0
> 38 1922???? 2?? 7? 0.0
> 39 1922???? 2?? 8? 0.0
> 40 1922???? 2?? 9? 0.0
>
> Thank you.
>
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
>
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