[R] equating approximate values
R. Michael Weylandt
michael.weylandt at gmail.com
Mon Dec 5 00:27:56 CET 2011
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:
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>>> Sent from the R help mailing list archive at Nabble.com.
>>>
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>>
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>>
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