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Thomas Preuth

2007-Feb-23 13:38 UTC

[R] TRUE/FALSE as numeric values

Hello,

I want to select in a column of a dataframe all numbers smaller than a 
value x
but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
 > test
 [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE 
FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
[18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  
TRUE  TRUE FALSE  TRUE  TRUE  TRUE
[35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE  
TRUE  TRUE FALSE FALSE  TRUE FALSE
[52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE

How can i get the values smaller than x and not the TRUE/FALSE reply?

Thanks in advance,
Thomas

Ranjan Maitra

2007-Feb-23 13:45 UTC

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[R] TRUE/FALSE as numeric values

On Fri, 23 Feb 2007 14:38:56 +0100 Thomas Preuth <preuth at slf.ch> wrote:
> Hello,
> 
> I want to select in a column of a dataframe all numbers smaller than a 
> value x
> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
>  > test
>  [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE 
> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  
> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE  
> TRUE  TRUE FALSE FALSE  TRUE FALSE
> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
> 
> How can i get the values smaller than x and not the TRUE/FALSE reply?
if the dataframe is called RSF_EU, and you want the entire dataframe for those
rows, then

RSF_EU [ (RSF_EU$AREA <= x ), ]

if you want to get only that column vector and nothing else

RSF_EU$AREA [ ( RSF_EU$AREA <= x ) ]

Such concepts are very well-explained in "An Introduction to R" which
you would benefit by reading at the earliest.

Ranjan

> Thanks in advance,
> Thomas
> 
> ______________________________________________
> 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
> and provide commented, minimal, self-contained, reproducible code.
>

ONKELINX, Thierry

2007-Feb-23 13:46 UTC

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[R] TRUE/FALSE as numeric values

RSF_EU$AREA[RSF_EU$AREA<=x]

------------------------------------------------------------------------
----

ir. Thierry Onkelinx

Instituut voor natuur- en bosonderzoek / Reseach Institute for Nature
and Forest

Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance

Gaverstraat 4

9500 Geraardsbergen

Belgium

tel. + 32 54/436 185

Thierry.Onkelinx op inbo.be

www.inbo.be 

 

Do not put your faith in what statistics say until you have carefully
considered what they do not say.  ~William W. Watt

A statistical analysis, properly conducted, is a delicate dissection of
uncertainties, a surgery of suppositions. ~M.J.Moroney
> -----Oorspronkelijk bericht-----
> Van: r-help-bounces op stat.math.ethz.ch [mailto:r-help-
> bounces op stat.math.ethz.ch] Namens Thomas Preuth
> Verzonden: vrijdag 23 februari 2007 14:39
> Aan: r-help op stat.math.ethz.ch
> Onderwerp: [R] TRUE/FALSE as numeric values
> 
> Hello,
> 
> I want to select in a column of a dataframe all numbers smaller than a
> value x
> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
>  > test
>  [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE
> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE
> TRUE  TRUE FALSE FALSE  TRUE FALSE
> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
> 
> How can i get the values smaller than x and not the TRUE/FALSE reply?
> 
> Thanks in advance,
> Thomas
> 
> ______________________________________________
> R-help op 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
> and provide commented, minimal, self-contained, reproducible code.

Henrique Dallazuanna

2007-Feb-23 13:49 UTC

head link

[R] TRUE/FALSE as numeric values

You can also:

test <- RSF_EU[which(RSF_EU$AREA<=x),]

On 23/02/07, Thomas Preuth <preuth@slf.ch> wrote:>
> Hello,
>
> I want to select in a column of a dataframe all numbers smaller than a
> value x
> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
> > test
> [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE
> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE
> TRUE  TRUE FALSE FALSE  TRUE FALSE
> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
>
> How can i get the values smaller than x and not the TRUE/FALSE reply?
>
> Thanks in advance,
> Thomas
>
> ______________________________________________
> R-help@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
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná
Brasil

	[[alternative HTML version deleted]]

Chuck Cleland

2007-Feb-23 13:50 UTC

head link

[R] TRUE/FALSE as numeric values

Thomas Preuth wrote:> Hello,
> 
> I want to select in a column of a dataframe all numbers smaller than a 
> value x
> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
>  > test
>  [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE 
> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  
> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE  
> TRUE  TRUE FALSE FALSE  TRUE FALSE
> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
> 
> How can i get the values smaller than x and not the TRUE/FALSE reply?
  This is covered in

http://cran.r-project.org/doc/manuals/R-intro.html

(Section 2.7; Index vectors; selecting and modifying subsets of a data set)

RSF_EU$AREA[RSF_EU$AREA <= x]

or to retain other columns in the data frame

subset(RSF_EU, AREA <= x)
> Thanks in advance,
> Thomas
> 
> ______________________________________________
> 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
> and provide commented, minimal, self-contained, reproducible code.
-- 
Chuck Cleland, Ph.D.
NDRI, Inc.
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
tel: (732) 512-0171 (M, W, F)
fax: (917) 438-0894

Gavin Simpson

2007-Feb-23 13:55 UTC

head link

[R] TRUE/FALSE as numeric values

On Fri, 2007-02-23 at 14:38 +0100, Thomas Preuth wrote:> Hello,
> 
> I want to select in a column of a dataframe all numbers smaller than a 
> value x
> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
>  > test
>  [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE 
> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  
> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE  
> TRUE  TRUE FALSE FALSE  TRUE FALSE
> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
> 
> How can i get the values smaller than x and not the TRUE/FALSE reply?
> 
> Thanks in advance,
> Thomas
You need to subset your object based on the results you achieved above.
What you did was only half the job. See this example, with a number of
ways to get what you want:

## some dummy data to work with
dat <- 10 * runif(100)
dat <- data.frame(AREA = dat, FOO = dat + rnorm(100))

## select values of AREA less than mean AREA
mn <- mean(dat$AREA)
want1 <- with(dat, AREA[AREA <= mn])
## or
want2 <- dat$AREA[dat$AREA <= mn]
## or
want3 <- subset(dat$AREA, dat$AREA <= mn)
## or
want4 <- subset(dat, AREA <= mn)$AREA
## check they all do same thing
all.equal(want1, want2, want3, want4) ## TRUE

want2 is closest to how you tried to do it:

dat$AREA[dat$AREA <= mn]
         ^^^^^^^^^^^^^^
Notice that you only did the inner bit marked, which as you found
returns TRUE/FALSE depending on whether that element of AREA met the
criterion of being less than or equal to your x. This information is
used to select elements from AREA using the subsetting functions for
objects.

HTH

G
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Prof Brian Ripley

2007-Feb-23 17:57 UTC

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[R] TRUE/FALSE as numeric values

It is inefficient to use which() rather than a logical index, since you 
allocate two numeric index vectors (one the length of the original 
vector) and use an interpreted function rather than optimized C code.
Also, in this usage which() handles NAs incorrectly.

I think the clearest answer is probably

    with(RSF_EU, AREA[AREA <= x])

On Fri, 23 Feb 2007, Henrique Dallazuanna wrote:
> You can also:
>
> test <- RSF_EU[which(RSF_EU$AREA<=x),]
>
> On 23/02/07, Thomas Preuth <preuth at slf.ch> wrote:
>>
>> Hello,
>>
>> I want to select in a column of a dataframe all numbers smaller than a
>> value x
>> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
>>> test
>> [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE
>> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
>> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
>> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
>> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE
>> TRUE  TRUE FALSE FALSE  TRUE FALSE
>> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
>>
>> How can i get the values smaller than x and not the TRUE/FALSE reply?
>>
>> Thanks in advance,
>> Thomas
>>
>> ______________________________________________
>> 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
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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