[R] Rounding fractional numbers to nearest fraction

[Liaw, Andy]

> From: Ken Termiso
> 
> Thx for the help...
> 
> mdiv <- function(dec)
> {
> 	dec <- dec * 4
> 	dec <- round(dec, 0)
> 	dec <- dec / 4
> 	dec
> }
> 
> where m is a matrix --
> 
> m1 <- apply(m, 1, mdiv)

You don't need the apply():

> m <- matrix(runif(6), 2, 3)
> m
          [,1]      [,2]      [,3]
[1,] 0.6885473 0.4598892 0.2738169
[2,] 0.2393461 0.8863284 0.7891100
> round(m * 4) / 4
     [,1] [,2] [,3]
[1,] 0.75  0.5 0.25
[2,] 0.25  1.0 0.75
 
> ...but it looks like as.integer(x.1*4)/4 or 
> (round(x.1*4,0))/4 might be 
> easier...

Be careful: as.integer() trucate the fractional part (so as.integer(1.999)
is 1 intead of 2), which may not be what you want.

Andy

 
> thx again,
> ken
> 
> >From: james.holtman at convergys.com
> >To: "Ken Termiso" <jerk_alert at hotmail.com>
> >Subject: Re: [R] Rounding fractional numbers to nearest fraction
> >Date: Wed, 25 May 2005 14:30:44 -0400
> >
> >
> >
> >
> >
> > > x.1
> >  [1] 1.07 1.11 1.27 1.59 0.97 0.76 2.23 0.98 0.71 0.88 1.19 1.02
> > > as.integer(x.1*4)/4
> >  [1] 1.00 1.00 1.25 1.50 0.75 0.75 2.00 0.75 0.50 0.75 1.00 1.00
> > >
> >
> >Jim
> >__________________________________________________________
> >James Holtman        "What is the problem you are trying to solve?"
> >Executive Technical Consultant  --  Convergys Labs
> >james.holtman at convergys.com
> >+1 (513) 723-2929
> >
> >
> >
> >                       "Ken Termiso"
> >                       <jerk_alert at hotmail.c        To:       
> >r-help at stat.math.ethz.ch
> >                       om>                          cc:
> >                       Sent by:                     Subject: 
>  [R] Rounding 
> >fractional numbers to nearest fraction
> >                       r-help-bounces at stat.m
> >                       ath.ethz.ch
> >
> >
> >                       05/25/2005 13:27
> >
> >
> >
> >
> >
> >Hi all,
> >
> >I've got a matrix of fractional data that is all positive 
> and greater than
> >zero that I would like to "loosely" classify, for lack of a 
> better word. It
> >
> >looks something like this :
> >
> >1.07   1.11   1.27   1.59   0.97   0.76
> >2.23   0.98   0.71   0.88   1.19   1.02
> >
> >
> >What I'm looking for is a way to round these numbers to the 
> nearest 0.25,
> >i.e. the above matrix would be transformed to :
> >
> >1.00   1.00   1.25   1.50   1.00   0.75
> >2.25   1.00   0.75   1.00   1.25   1.00
> >
> >
> >Anyone have a clever way to do this??
> >
> >Thanks in advance,
> >Ken
> >
> >______________________________________________
> >R-help at stat.math.ethz.ch mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help
> >PLEASE do read the posting guide!
> >http://www.R-project.org/posting-guide.html
> >
> >
> 
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