[R] equating approximate values

[R. Michael Weylandt]

My apologies: you need an abs() call as well:

which(abs(outer(x, y, "-")) < threshold, arr.ind = TRUE)

Michael

On Sun, Dec 4, 2011 at 6:25 PM, R. Michael Weylandt
<michael.weylandt at gmail.com> wrote:
> Not sure what to make of the fact that your x, y are of different
> lengths: if you mean to check all possible pairings, this is probably
> what you need:
>
> which(outer(x, y, "-") < threshold, arr.ind = TRUE)
>
> Michael
>
> On Sun, Dec 4, 2011 at 2:24 PM, andrija djurovic <djandrija at gmail.com> wrote:
>> Hi. Maybe this can help you (you can try additionally to incorporate
>> threshold):
>>
>>> set.seed(1)
>>> x<-rnorm(10,10,1)
>>> values <- sample(1:10,10)  #values that we are looking for
>>> mat <- matrix(c(x,values),ncol=2)
>>>
>>> closest<-function(x,values)    #function is an example from The R book
>> (Crawley)
>> + {
>> + x[which(abs(x-values)==min(abs(x-values)))]
>> + }
>>>
>>> apply(mat[,2,drop=FALSE],1,function(y) closest(mat[,1],y))
>>  [1] 10.183643  9.164371  9.164371  9.164371  9.164371  9.164371  9.164371
>>  9.164371
>>  [9]  9.164371  9.164371
>>
>>
>> On Sun, Dec 4, 2011 at 7:00 PM, vamshi999 <vamshi999 at gmail.com> wrote:
>>
>>> Hello List,
>>>
>>> I am having trouble finding the command for my problem.
>>>
>>> I have two arrays x and y. now i would like to compare the values of x and
>>> y
>>> and then get the index of x which is exactly or approximately equal(+/-
>>> some
>>> value ) to the values in y.
>>>  x <- runif(100,min=0,max=5)
>>>  y <- runif(10,min=0,max=5)
>>>
>>>
>>> the threshold value(+/-) value can vary. for this example lets take it to
>>> be
>>> .5
>>>
>>> I know the regular method of doing this by writing different if and for
>>> loops. But i have very big dataframe the computation time is very high for
>>> this method. can anyone please tell me if there any functions to do this.
>>>
>>> thank you for your help.
>>>
>>> --
>>> View this message in context:
>>> http://r.789695.n4.nabble.com/equating-approximate-values-tp4157551p4157551.html
>>> Sent from the R help mailing list archive at Nabble.com.
>>>
>>> ______________________________________________
>>> 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.
>>>
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.