[R] merging and obtaining the nearest value

[Rui Barradas]

Hello,

Em 19-08-2012 17:33, William Dunlap escreveu:
> Did you omit
>    m <- merge(A, B)
> from your code?

Yes, completely forgot! It should be before the split/lapply.

Rui Barradas
>
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
>> Of Rui Barradas
>> Sent: Sunday, August 19, 2012 3:52 AM
>> To: Francesco
>> Cc: r-help
>> Subject: Re: [R] merging and obtaining the nearest value
>>
>> 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
>>>
>>> ______________________________________________
>>> 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.
>> ______________________________________________
>> 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.