Re: [R] Logical operations or selecting data from data.frames

From: Roger Bivand <Roger.Bivand_at_nhh.no>
Date: Tue 09 Jan 2007 - 18:05:25 GMT


On Tue, 9 Jan 2007, Benjamin Dickgiesser wrote:

> I suppose this doesn't work for the same reason as
> sdata$VaR < sdata$DdtdAbs && sdata$DdtdDuration >= 1
>
> does only return FALSE and not a vector of TRUE and FALSE as

See ?"&":

     '&' and '&&' indicate logical AND and '|' and '||' indicate
     logical OR.  The shorter form performs elementwise comparisons in
     much the same way as arithmetic operators.  The longer form
     evaluates left to right examining only the first element of each
     vector...

a <- rep(c(1,2), 5)
b <- rep(1,10)
a > 1 && b <= 1
a > 1 & b <= 1

>
> sdata$VaR < sdata$DdtdAbs
>
> would return.
>
> Is there a ways around this?
> Benjamin
>
> On 1/9/07, Benjamin Dickgiesser <dickgiesser@gmail.com> wrote:
> > Hi all,
> >
> > why doesn't something like this does not work?
> >
> > speedy <-
> > (sdata$VaR < sdata$DdtdAbs) && sdata$DdtdDuration >= qpois(pct,lambda) &&
> > sdata$Ddtd > MinDD
> >
> > or sdata$Ddtd[sdata$Ddtd > 0 && sdata$VaR < sdata$DdtdAbs]
> >
> > sdata looks like this:
> >
> > dataId date value Ddtd VaR DdtdAbs DdtdDuration
> > 18948 79637 2004-07-27 10085.10 NA NA 0.00 0
> > 18949 79638 2004-07-28 10117.10 NA NA 0.00 0
> > 18950 79639 2004-07-29 10129.20 NA NA 0.00 0
> > 18951 79640 2004-07-30 10139.70 NA NA 0.00 0
> > 18952 79641 2004-08-02 10179.20 NA NA 0.00 0
> > 18953 79642 2004-08-03 10120.20 0.579613329 336.060090 59.00 1
> > 18954 79643 2004-08-04 10126.50 NA NA 0.00 0
> > 18955 79644 2004-08-05 9963.03 1.614279366 334.306978 163.47 1
> > 18956 79645 2004-08-06 9815.33 3.072828717 386.173057 311.17 2
> > 18957 79646 2004-08-09 9814.66 3.079445020 420.167049 311.84 3
> > 18958 79647 2004-08-10 9944.67 NA NA 0.00 0
> > 18959 79648 2004-08-11 9938.32 0.063853300 328.315992 6.35 1
> > 18960 79649 2004-08-12 9814.59 1.308037371 379.182568 130.08 2
> >
> > I am trying to select rows from the data.frame which have Ddtd > x,
> > VaR < DdtdAbs and DdtdDuration > z.
> >
> > Thank you,
> > Benjamin
> >

>
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>

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand@nhh.no

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Received on Wed Jan 10 08:46:59 2007

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