Not in the direction I was looking, but your function "fff" really speed
up the process, and using it along with "fff3" is fine for me.
Thanks
Petr PIKAL wrote:
> Hi
>
> r-help-boun...@r-project.org napsal dne 16.06.2009 14:31:21:
>
>
>> Hi Jim,
>>
>> What you are saying is correct. Although, my computer might not have
>> same speed and I am getting the following for 10M entries:
>>
>> user system elapsed
>> 0.559 0.038 0.607
>>
>
> With numbers you may speed it a bit by
>
>
>> x = c(1,2,rep(1,10000000))
>> system.time(print(all(x[1] == x)))
>>
> [1] FALSE
> user system elapsed
> 0.13 0.01 0.14
>
>> fff<-function(x) {lx<-length(x); (x[1]*lx)==sum(x)}
>> system.time(print(fff(x)))
>>
> [1] FALSE
> user system elapsed
> 0.03 0.00 0.03
>
> and with character vector I would try this
>
>
>> x<-c("a", "b", rep("a", 10000000))
>>
>
>
>> fff2<-function(x) length(unique(x))==1
>> system.time(print(fff2(x)))
>>
> [1] FALSE
> user system elapsed
> 0.39 0.08 0.47
>
> If you are sure that first let say 1000 can be representative try
>
>
>> fff2<-function(x) length(unique(x[1:1000]))==1
>> system.time(print(fff2(x)))
>>
> [1] FALSE
> user system elapsed
> 0 0 0
>
> or put a double check, try first 1000 and if there is no difference check
> the rest
>
> fff3<-function(x) if (length(unique(x[1:1000]))==1) length(unique(x))==1
> else FALSE
>
> Regards
> Petr
>
>
>
>> Moreover, in the case of character vectors, it gets more than double.
>>
>> In my modeling, which is already highly time consuming, I need to do
>> check this for few thousand vectors and the entries can easily be 10M in
>>
>
>
>> each vector. So I am just looking for any possibilities of time saving.
>> I am pretty sure that whenever elements are not all equal, it can be
>> concluded from any few entries (most of the times). It will be worth if
>> I can find a way which stops checking further the moment it find two
>> distinct elements.
>>
>> Regards
>> Utkarsh
>>
>>
>> jim holtman wrote:
>>
>>> Just check that the first (or any other element) is equal to all the
>>>
> rest:
>
>>>> x = c(1,2,rep(1,10000000)) # 10,000,000
>>>> system.time(print(all(x[1] == x)))
>>>>
>>> [1] FALSE
>>> user system elapsed
>>> 0.18 0.00 0.19
>>>
>>>
>>> This was for 10M entries.
>>>
>>> On Tue, Jun 16, 2009 at 7:42 AM, utkarshsinghal
>>> <utkarsh.sing...@global-analytics.com
>>> <mailto:utkarsh.sing...@global-analytics.com>> wrote:
>>>
>>>
>>> Hi All,
>>>
>>> There are several replies to the question below, but I think there
>>> must
>>> exist a better way of doing so.
>>> I just want to check whether all the elements of a vector are
>>>
> same. My
>
>>> vector has one million elements and it is highly likely that there
>>>
> are
>
>>> distinct elements in the first few itself. For example:
>>>
>>> > x = c(1,2,rep(1,100000))
>>>
>>> I want the answer as FALSE, which is clear from the first two
>>> observations itself and we don't need to check for the rest.
>>>
>>> Does anybody know the most efficient way of doing this?
>>>
>>> Regards
>>> Utkarsh
>>>
>>>
>>>
>>> From: Francisco J. Zagmutt <gerifalte28_at_hotmail.com
>>> <http://gerifalte28_at_hotmail.com/>
>>> <mailto:gerifalte28_at_hotmail.com
>>> <mailto:gerifalte28_at_hotmail.com
>>>
>> ?Subject=Re:%20%5BR%5D%20Testing%
>> 20if%20all%20elements%20are%20equal%20in%20a%20vector/matrix>>
>>
>>> Date: Tue 30 Aug 2005 - 06:05:20 EST
>>>
>>>
>>> Hi Doran
>>>
>>> The documentation for isTRUE reads 'isTRUE(x)' is an abbreviation
>>>
> of
>
>>> 'identical(TRUE,x)' so actually Vincent's solutions is "cleaner"
>>>
> than
>
>>> using identical :)
>>>
>>> Cheers
>>>
>>> Francisco
>>>
>>> />From: "Doran, Harold" <hdo...@air.org <mailto:hdo...@air.org>> /
>>> />To: <vincent.gou...@act.ulaval.ca
>>> <mailto:vincent.gou...@act.ulaval.ca>>, <r-h...@stat.math.ethz.ch
>>> <mailto:r-h...@stat.math.ethz.ch>> /
>>> />Subject: Re: [R] Testing if all elements are equal in a
>>> vector/matrix /
>>> />Date: Mon, 29 Aug 2005 15:49:20 -0400 /
>>> /> /
>>> >See ?identical
>>> <
>>>
> http://tolstoy.newcastle.edu.au/R/help/05/08/11201.html#11202qlink1>
>
>>> /> /
>>> />-----Original Message----- /
>>> />From: r-help-boun...@stat.math.ethz.ch
>>> <mailto:r-help-boun...@stat.math.ethz.ch> /
>>> />[mailto:r-help-boun...@stat.math.ethz.ch
>>> <mailto:r-help-boun...@stat.math.ethz.ch>] On Behalf Of Vincent
>>> Goulet /
>>> />Sent: Monday, August 29, 2005 3:35 PM /
>>> />To: r-h...@stat.math.ethz.ch <mailto:r-h...@stat.math.ethz.ch> /
>>> />Subject: [R] Testing if all elements are equal in a
>>>
> vector/matrix /
>
>>> /> /
>>> /> /
>>> />Is there a canonical way to check if all elements of a vector or
>>> matrix are /
>>> />the same? Solutions below work, but look hackish to me. /
>>> /> /
>>> /> > x <- rep(1, 10) /
>>> /> > all(x == x[1]) # == operator does not provide for small
>>> differences /
>>> */>[1] TRUE /
>>> */> > isTRUE(all.equal(x, rep(x[1], length(x)))) # ugly /
>>> */>[1] TRUE /
>>> */> /
>>> />Best, /
>>> /> /
>>> />Vincent /
>>> />-- /
>>> /> Vincent Goulet, Associate Professor /
>>> /> École d'actuariat /
>>> /> Université Laval, Québec /
>>> /> Vincent.Goulet_at_act.ulaval.ca
>>> <http://vincent.goulet_at_act.ulaval.ca/>
>>> <mailto:Vincent.Goulet_at_act.ulaval.ca
>>> <mailto:Vincent.Goulet_at_act.ulaval.ca>?Subject=Re:%20%5BR%5D%
>>>
>> 20Testing%20if%20all%20elements%20are%20equal%20in%20a%20vector/matrix>
>>
>>> http://vgoulet.act.ulaval.ca <http://vgoulet.act.ulaval.ca/> /
>>> /> /
>>> />______________________________________________ /
>>> />r-h...@stat.math.ethz.ch <mailto:r-h...@stat.math.ethz.ch>
>>> mailing list /
>>> />https://stat.ethz.ch/mailman/listinfo/r-help /
>>> />PLEASE do read the posting guide! /
>>> />http://www.R-project.org/posting-guide.html
>>> <http://www.r-project.org/posting-guide.html> /
>>> /> /
>>> />______________________________________________ /
>>> />r-h...@stat.math.ethz.ch <mailto:r-h...@stat.math.ethz.ch>
>>> mailing list /
>>> />https://stat.ethz.ch/mailman/listinfo/r-help /
>>> />PLEASE do read the posting guide! /
>>> />http://www.R-project.org/posting-guide.html
>>> <http://www.r-project.org/posting-guide.html> /
>>>
>>> [[alternative HTML version deleted]]
>>>
>>>
>>> ______________________________________________
>>> R-help@r-project.org <mailto: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
>>> <http://www.r-project.org/posting-guide.html>
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>>
>>>
>>> --
>>> Jim Holtman
>>> Cincinnati, OH
>>> +1 513 646 9390
>>>
>>> What is the problem that you are trying to solve?
>>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>
>
>
>
>
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