[R] Problem with <= (less than or equal): not giving the expected result

[Rainer Johannes]

Thanks Adrian and Thierry (from the previous answer).

I was aware of the all.equal function, but there is nothing similar for <= (e.g. all.smallerEqual)?

cheers, jo

On 05 Apr 2016, at 14:31, Adrian Dușa <dusa.adrian at unibuc.ro<mailto:dusa.adrian at unibuc.ro>> wrote:

Yes, that does have to do with floating point representation.
I use this function for these types of comparisons (works with values as well as with vectors):

check.equal <- function(x, y) {
    check.vector <- as.logical(unlist(lapply(x, all.equal, y)))
    check.vector[is.na<http://is.na/>(check.vector)] <- FALSE
    return(check.vector)
}

See:
?all.equal

Hth,
Adrian

On Tue, Apr 5, 2016 at 2:34 PM, Rainer Johannes <Johannes.Rainer at eurac.edu<mailto:Johannes.Rainer at eurac.edu>> wrote:
Dear All,

I have the following problem:

I have a function in which I check if the difference between values is smaller or equal to a certain threshold. I however realized that I might get there some unexpected results:

> abs(1 - 0.95) >= 0.05
[1] TRUE
## So that’s fine, but:
> abs(1 - 0.95) <= 0.05
[1] FALSE

Apparently, abs(1 - 0.95) is not equal to 0.05, which I find however quite disturbing.

Along these lines:
> abs(0.95 - 1) > 0.05
[1] TRUE
> abs(0.95 - 1) < 0.05
[1] FALSE

I guess that has to do with the floating point representation of the data?

Is there something I miss or is there any solution to this?
Thanks for any help!

cheers, jo



I tried this on different R-version (including 3.2.3 and 3.3.0 alpha); The R-version I used for the code above is:

> sessionInfo()
R version 3.0.2 (2013-09-25)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base
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--
Adrian Dusa
University of Bucharest
Romanian Social Data Archive
Soseaua Panduri nr.90
050663 Bucharest sector 5
Romania


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