Re: [R] Data length mismatch.

From: Don MacQueen <macq_at_llnl.gov>
Date: Sat, 26 Jul 2008 18:33:37 -0700

I think the

     merge()
function should be adequate for this task. Here is an example.

> A <- data.frame(day=1:5, x=runif(5))
> B <- data.frame(day=3:7, x=runif(5))
> A

   day x

1   1 0.9764534
2   2 0.9693998
3   3 0.1324933
4   4 0.8311153
5   5 0.3264465

> B <- data.frame(day=3:8, x=runif(6))
> B

   day x

1   3 0.5096328
2   4 0.6043132
3   5 0.7947639
4   6 0.7619096
5   7 0.1571041
6   8 0.3473159

> D <- merge(A,B, by='day',all=TRUE)
> D$diff <- D$x.x - D$x.y

> D

   day       x.x       x.y       diff
1   1 0.9764534        NA         NA
2   2 0.9693998        NA         NA
3   3 0.1324933 0.5096328 -0.3771395
4   4 0.8311153 0.6043132  0.2268022
5   5 0.3264465 0.7947639 -0.4683174
6   6        NA 0.7619096         NA
7   7        NA 0.1571041         NA
8   8        NA 0.3473159         NA

-Don

At 2:26 PM -0700 7/26/08, <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
>
>______________________________________________
>R-help_at_r-project.org mailing list
>https:// stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide http:// www. R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

-- 
---------------------------------
Don MacQueen
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
macq_at_llnl.gov

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Received on Sun 27 Jul 2008 - 01:37:38 GMT

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