[R] Data length mismatch.
Gabor Grothendieck
ggrothendieck at gmail.com
Sat Jul 26 23:53:37 CEST 2008
Look at merge.zoo
> library(zoo)
> dput(A)
structure(list(DayOfYear = 1:5, x = c(1429L, 3952L, 3049L, 2844L,
2219L)), .Names = c("DayOfYear", "x"), class = "data.frame", row.names = c("1",
"2", "3", "4", "5"))
> B <- A[c(2,4),]
> Az <- zoo(A$x, A$DayOfYear)
> Bz <- zoo(B$x, B$DayOfYear)
> merge(Az, Bz, fill = 0)
Az Bz
1 1429 0
2 3952 3952
3 3049 0
4 2844 2844
5 2219 0
> merge(Az, Bz, fill = 0) %*% c(1, -1)
[,1]
[1,] 1429
[2,] 0
[3,] 3049
[4,] 0
[5,] 2219
On Sat, Jul 26, 2008 at 5:26 PM, <rkevinburton at charter.net> wrote:
> I have two vectos (list) that represent a years of data. Each "row" is represented by the day of year and the quantity that was sold for that day. I would like to form a new vector that is the difference between the two years of data. A sample of A (and similarly B) looks like:
>
>> A[1:5,]
> DayOfYear x
> 1 1 1429
> 2 2 3952
> 3 3 3049
> 4 4 2844
> 5 5 2219
>>
>
> D <- A - B
>
> This works just fine if A and B are both the same length. How is the best way to handle the situation where A and B are of different lengths? If the day of year exists in both vectors (lists) then I just want the coorespondng "row" in D to be the difference btween A and B values. If the "row" doesn't exist in either A or B then the difference should be treated as if the missing "row" was zero. Is this feasible?
>
> Thank you.
>
> Kevin
>
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