Thank you for the difference between print() and round().

I have never noticed that!!

Best,

KK


On Tue, Mar 25, 2014 at 3:17 PM, William Dunlap <wdunlap@tibco.com> wrote:

> > The round() function lets you specify the number of decimal
> > places directly:
> >
> > round(vars, 4)
>
> round() and print() don't always agree on meaning of "the
> number of digits".  In addition, rounding is not a transitive
> operation - rounding a rounded number does not always
> give you a rounding of the original number.
> E.g., with R-3.0.2 on Windows:
>    >  print(round(9/11, digits=3), digits=16)
>    [1] 0.8179999999999999
>    > print(round(1.11111146, digits=7), digits=7)
>    [1] 1.111112
>
> If you want to control the number of printed digits it is better to
> control print() itself, not use round().
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> > -----Original Message-----
> > From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org]
> On Behalf
> > Of David Carlson
> > Sent: Tuesday, March 25, 2014 7:02 AM
> > To: 'Qiang Kou'; 'Pavneet Arora'
> > Cc: 'R help'
> > Subject: Re: [R] Digits in R
> >
> > The digits option gives you the number of significant digits
> > (ignoring leading zeros after the decimal) and it operates on a
> > column by column basis. The first and second columns have values
> > with a leading zero after the decimal (-0.04074 in both columns)
> > so R prints five decimal places to get four significant digits
> > (4074). In the third and fourth columns four decimals are enough
> > so R uses that.
> >
> > The round() function lets you specify the number of decimal
> > places directly:
> >
> > round(vars, 4)
> >
> > To set and reset the "digits" option:
> >
> > oldpar <- options(digits=4) # Set digits and save the default
> > value
> >
> > # Commands using digits=4
> >
> > options(oldpar) # Resets to the default value
> >
> > -------------------------------------
> > David L Carlson
> > Department of Anthropology
> > Texas A&M University
> > College Station, TX 77840-4352
> >
> >
> > -----Original Message-----
> > From: r-help-bounces@r-project.org
> > [mailto:r-help-bounces@r-project.org] On Behalf Of Qiang Kou
> > Sent: Tuesday, March 25, 2014 8:45 AM
> > To: Pavneet Arora
> > Cc: R help
> > Subject: Re: [R] Digits in R
> >
> > Have you tried "round(vars, digits = 4)" ?
> >
> > KK
> >
> >
> > On Tue, Mar 25, 2014 at 7:17 AM, Pavneet Arora <
> > pavneet.arora@uk.rsagroup.com> wrote:
> >
> > > Hello All,
> > >
> > > I am new in R, so please excuse the basic questions.
> > > But how do you change the number of digits to be displayed?
> > >
> > > I have done the following, hoping I will get 4 decimal places
> > in my
> > > answer:
> > >
> > > vars <- var(cbind(Sepal.l,Sepal.w,Petal.l,Petal.w))
> > > print(vars,digits=4)
> > >
> > > But as seen below from the output, that is not the case
> > >
> > > > print(vars,digits=4)
> > >          Sepal.l  Sepal.w Petal.l Petal.w
> > > Sepal.l  0.68569 -0.04074  1.2743  0.5163
> > > Sepal.w -0.04074  0.19363 -0.3287 -0.1212
> > > Petal.l  1.27432 -0.32873  3.1163  1.2956
> > > Petal.w  0.51627 -0.12124  1.2956  0.5810
> > >
> > > How come the Sepal.l and Sepal.w does not come with only 4
> > decimal places.
> > > Can someone tell me where I am going wrong?
> > >
> > > Also if I use the "options(digits=4)"- How do I make it to go
> > back to
> > > Normal or default, which is 7 in this case.?
> > >
> > >
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> >
> > --
> > Qiang Kou
> > qkou@umail.iu.edu
> > School of Informatics and Computing, Indiana University
> >
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> >
> > ______________________________________________
> > 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.
> >
> > ______________________________________________
> > 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.
>



-- 
Qiang Kou
qkou@umail.iu.edu
School of Informatics and Computing, Indiana University

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