[R] unique and precision of long integers

[Christophe Declercq]

Hi, Michael

> De : owner-r-help at stat.math.ethz.ch
> [mailto:owner-r-help at stat.math.ethz.ch]De la part de Michael Herron
> Envoyé : lundi 14 mai 2001 17:09
> À : r-help at stat.math.ethz.ch
> Objet : [R] unique and precision of long integers
>
>
>
> Hello.
>
> I have a dataset with about 500,000 observations, most of which are
> not unique.  The first 10 observations look like
>
> 901000000000100000010100101011002
> 901101101110100000010100101011002
[...]
> I read in the data with scan(), and then use unique() to get the
> unique observations.  But, when I print these elements to a file I
> lose precision.

If you have long strings of digits, you can 'scan' them as character
(actually, they are not exactly numbers) and manipulate them afterwards:

> x<-scan("foo.dat", what="")
> x
 [1] "901000000000100000010100101011002"
"901101101110100000010100101011002"
 [3] "901000000000100000010100000001002"
"901000000000100000010101001011002"
 [5] "901000000000100000010101010011002"
"901000000000100000010100110101002"
 [7] "901000000000100000010100101011002"
"900000000000100000010010101011002"
 [9] "901000000000100000010100101101002"
"901000000000100000010100101011002"
> write(x,"",ncol=1)
901000000000100000010100101011002
901101101110100000010100101011002
901000000000100000010100000001002
901000000000100000010101001011002
901000000000100000010101010011002
901000000000100000010100110101002
901000000000100000010100101011002
900000000000100000010010101011002
901000000000100000010100101101002
901000000000100000010100101011002

I hope it helps.

Christophe

--
Christophe DECLERCQ, MD
Observatoire Régional de la Santé Nord-Pas-de-Calais
13, rue Faidherbe 59046 LILLE Cedex FRANCE
Phone +33 3 20 15 49 24
Fax   +33 3 20 55 92 30
E-mail c.declercq at orsnpdc.org


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