Hello,
Yes you can, if you have memory problems, say so and we'll see it then.
In the mean time, there's something you should change, to allow for
several minima but to only return one per combination of TYPE and DATE.
Replace this
x[which(min(a) == a), ]
by this
x[which.min(a), ]
Rui Barradas
Em 19-08-2012 12:00, Francesco escreveu:
Dear Riu, Many thanks for your suggestion
However these are just simplified examples... in reality the dataset A
contains millions of observations and B several thousands of rows...
Could I still use a modified form of your suggestion?
Thanks
On 19 August 2012 12:51, Rui Barradas <ruipbarra...@sapo.pt> wrote:
Hello,
Try the following.
A <- read.table(text="
TYPE DATE
A 2
A 5
A 20
B 10
B 2
", header = TRUE)
B <- read.table(text="
TYPE Special_Date
A 2
A 6
A 20
A 22
B 5
B 6
", header = TRUE)
result <- do.call( rbind, lapply(split(merge(A, B), list(m$DATE, m$TYPE)),
function(x){
a <- abs(x$DATE - x$Special_Date)
if(nrow(x)) x[which(min(a) == a), ] }) )
result$Difference <- result$DATE - result$Special_Date
result$Special_Date <- NULL
rownames(result) <- seq_len(nrow(result))
result
Also, it's a good practice to post data examples using dput(). For instance,
dput(A)
structure(list(TYPE = structure(c(1L, 1L, 1L, 2L, 2L), .Label = c("A",
"B"), class = "factor"), DATE = c(2L, 5L, 20L, 10L, 2L)), .Names = c("TYPE",
"DATE"), class = "data.frame", row.names = c(NA, -5L))
Now all we have to do is run the statement A <- structure(... etc...) to
have an exact copy of the data example.
Anyway, your example with input and the wanted result was very welcome.
Hope this helps,
Rui Barradas
Em 19-08-2012 11:10, Francesco escreveu:
Dear R-help
Î would like to know if there is a short solution in R for this
merging problem...
Let say I have a dataset A as:
TYPE DATE
A 2
A 5
A 20
B 10
B 2
(there can be duplicates for the same type and date)
and I have another dataset B as :
TYPE Special_Date
A 2
A 6
A 20
A 22
B 5
B 6
The question is : I would like to obtain the difference between the
date of each observation in A and the closest special date in B with
the same type. In case of ties I would take the latest date of the
two.
For example I would obtain here
TYPE DATE Difference
A 2 0=2-2
A 5 -1=5-6
A 20 0=20-20
B 10 +4=10-6
B 2 -3=2-5
Do you know how to (simply?) obtain this in R?
Many thanks!
Best Regards
______________________________________________
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PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@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.
______________________________________________
R-help@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.
