[R] seeking advice about rounding error and %%

[Uwe Ligges]

Actually
   sapply(x %% 1, function(x) isTRUE(all.equal(x, 0)))
seems to be the way to go.

Uwe Ligges



On 14.08.2011 07:17, Ken wrote:
> How about something like:
> If(round(x)!=x){zap} not exactly working code but might help
>
>    Ken
> On Aug 13, 2554 BE, at 3:42 PM, Paul Johnson<pauljohn32 at gmail.com>  wrote:
>
>> A client came into our consulting center with some data that had been
>> damaged by somebody who opened it in MS Excel.  The columns were
>> supposed to be integer valued, 0 through 5, but some of the values
>> were mysteriously damaged. There were scores like 1.18329322 and such
>> in there.  Until he tracks down the original data and finds out what
>> went wrong, he wants to take all fractional valued scores and convert
>> to NA.
>>
>> As a quick hack, I suggest an approach using %%
>>
>>> x<- c(1,2,3,1.1,2.12131, 2.001)
>>> x %% 1
>> [1] 0.00000 0.00000 0.00000 0.10000 0.12131 0.00100
>>> which(x %% 1>  0)
>> [1] 4 5 6
>>> xbad<- which(x %% 1>  0)
>>> x[xbad]<- NA
>>> x
>> [1]  1  2  3 NA NA NA
>>
>> I worry about whether x %% 1 may ever return a non zero result for an
>> integer because of rounding error.
>>
>> Is there a recommended approach?
>>
>> What about zapsmall on the left, but what on the right of>?
>>
>> which( zapsmall(x %% 1)>   0 )
>>
>>
>> Thanks in advance
>>
>> --
>> Paul E. Johnson
>> Professor, Political Science
>> 1541 Lilac Lane, Room 504
>> University of Kansas
>>
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>
> ______________________________________________
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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.