[R] Number of digits to display?

[David L Carlson]

Just to elaborate on Marc's comment:

> set.seed(42)
> x <- runif(1)
> dput(x)             # What R is storing as x
0.914806043496355
> print(x)            # Ways to display an approximation of x
[1] 0.914806
> print(x, digits=3)
[1] 0.915
> round(x, 2)
[1] 0.91
> signif(x, 4)
[1] 0.9148
> library(MASS)
> fractions(x)
[1] 7334/8017
> dput(x)             # But x is still the same
0.914806043496355


David L. Carlson
Department of Anthropology
Texas A&M University

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Marc Schwartz
Sent: Monday, October 26, 2015 2:40 PM
To: Judson <judsonblake at msn.com>
Cc: R-help <r-help at r-project.org>
Subject: Re: [R] Number of digits to display?


> On Oct 26, 2015, at 11:43 AM, Judson <judsonblake at msn.com> wrote:
> 
> How do I control the number of digits to display, 
> say, in a matrix, without rounding or losing accuracy
> in subsequent calculations?     
> round() of course reduces accuracy.   
> 
> Also, if all my results
> are really fractions, is there a way to display 
> them as fractions of integers rather than 
> decimal expressions?   
> 
> ................... judson blake


Hi,

You need to differentiate between the way in which R *stores* numeric values and the way in which it *displays* numeric values.

If you want to affect the display of values in routine output, see ?options and note 'digits' and 'scipen'.

Also see ?print.default.

Those approaches do not affect the precision of calculations on the *stored* values.

For fractions, see:

  require(MASS)
  ?fractions

Regards,

Marc Schwartz

______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.