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Shubha Vishwanath Karanth

2007-Feb-19 13:36 UTC

[R] categorical column to numeric column

Hi R,

 

Let 'dd' be a data frame given as:

 

dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))

 

Now I want to create a column 'g' such that if dd$aa=a then dd$g=1 else
dd$g= -1 .

 

So, I gave the below syntax:

 

if((dd$aa)=="a") dd$g=1 else dd$g= -1

 

But I get the error message as:

Warning message: 

the condition has length > 1 and only the first element will be used in:
if ((dd$aa) == "a") dd$g = 1 else dd$g = -1 

 

and dd
 
> dd
  aa bb g

1  a  1 1

2  a  1 1

3  b  1 1

4  a  2 1

5  b  3 1

6  b  4 1
> 
 

Please let me know what is the error I am doing?

 

 

 

 


	[[alternative HTML version deleted]]

ONKELINX, Thierry

2007-Feb-19 14:09 UTC

head link

[R] categorical column to numeric column

Maybe this isn't the most elegant way, but it should work.
dd$g <- -1
dd$g[dd$aa == "a"] <- 1

Cheers,

Thierry
------------------------------------------------------------------------
----

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 Shubha Vishwanath
Karanth
Verzonden: maandag 19 februari 2007 14:36
Aan: r-help
Onderwerp: [R] categorical column to numeric column

Hi R,

 

Let 'dd' be a data frame given as:

 

dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))

 

Now I want to create a column 'g' such that if dd$aa=a then dd$g=1 else
dd$g= -1 .

 

So, I gave the below syntax:

 

if((dd$aa)=="a") dd$g=1 else dd$g= -1

 

But I get the error message as:

Warning message: 

the condition has length > 1 and only the first element will be used in:
if ((dd$aa) == "a") dd$g = 1 else dd$g = -1 

 

and dd
 
> dd
  aa bb g

1  a  1 1

2  a  1 1

3  b  1 1

4  a  2 1

5  b  3 1

6  b  4 1
> 
 

Please let me know what is the error I am doing?

 

 

 

 


	[[alternative HTML version deleted]]

______________________________________________
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.

Duncan Murdoch

2007-Feb-19 14:11 UTC

head link

[R] categorical column to numeric column

On 2/19/2007 8:36 AM, Shubha Vishwanath Karanth wrote:> Hi R,
> 
>  
> 
> Let 'dd' be a data frame given as:
> 
>  
> 
>
dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))
> 
>  
> 
> Now I want to create a column 'g' such that if dd$aa=a then dd$g=1
else
> dd$g= -1 .
> 
>  
> 
> So, I gave the below syntax:
> 
>  
> 
> if((dd$aa)=="a") dd$g=1 else dd$g= -1
if() looks at just the first entry; it's designed for flow of control 
rather than vectorized calculations.  You want ifelse():

ifelse( dd$aa == "a", 1, -1)

Duncan Murdoch>  
> 
> But I get the error message as:
> 
> Warning message: 
> 
> the condition has length > 1 and only the first element will be used in:
> if ((dd$aa) == "a") dd$g = 1 else dd$g = -1 
> 
>  
> 
> and dd> 
>  
> 
>> dd
> 
>   aa bb g
> 
> 1  a  1 1
> 
> 2  a  1 1
> 
> 3  b  1 1
> 
> 4  a  2 1
> 
> 5  b  3 1
> 
> 6  b  4 1
> 
>> 
> 
>  
> 
> Please let me know what is the error I am doing?
> 
>  
> 
>  
> 
>  
> 
>  
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.

Stephen Tucker

2007-Feb-19 14:26 UTC

head link

[R] categorical column to numeric column

try

dd$g <- ifelse(dd$aa=="a",1,-1)

and in general, you can convert categorical data (factors) into integers with
as.integer(), though the values will be positive:

dd$f <- as.integer(factor(dd$aa))


--- Shubha Vishwanath Karanth <shubhak at ambaresearch.com> wrote:
> Hi R,
> 
>  
> 
> Let 'dd' be a data frame given as:
> 
>  
> 
>
dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))
> 
>  
> 
> Now I want to create a column 'g' such that if dd$aa=a then dd$g=1
else
> dd$g= -1 .
> 
>  
> 
> So, I gave the below syntax:
> 
>  
> 
> if((dd$aa)=="a") dd$g=1 else dd$g= -1
> 
>  
> 
> But I get the error message as:
> 
> Warning message: 
> 
> the condition has length > 1 and only the first element will be used in:
> if ((dd$aa) == "a") dd$g = 1 else dd$g = -1 
> 
>  
> 
> and dd> 
>  
> 
> > dd
> 
>   aa bb g
> 
> 1  a  1 1
> 
> 2  a  1 1
> 
> 3  b  1 1
> 
> 4  a  2 1
> 
> 5  b  3 1
> 
> 6  b  4 1
> 
> > 
> 
>  
> 
> Please let me know what is the error I am doing?
> 
>  
> 
>  
> 
>  
> 
>  
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.
> 



 
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Philipp Pagel

2007-Feb-19 14:56 UTC

head link

[R] categorical column to numeric column

> Let 'dd' be a data frame given as:
> 
>
dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))
> 
> Now I want to create a column 'g' such that if dd$aa=a then dd$g=1
else
> dd$g= -1 .
You need to use ifelse instead of the if ... else construction:

dd$g = ifelse(dd$a=='a', 1, -1)

cu
	Philipp

-- 
Dr. Philipp Pagel                            Tel.  +49-8161-71 2131
Dept. of Genome Oriented Bioinformatics      Fax.  +49-8161-71 2186
Technical University of Munich
Science Center Weihenstephan
85350 Freising, Germany

 and

Institute for Bioinformatics / MIPS          Tel.  +49-89-3187 3675
GSF - National Research Center               Fax.  +49-89-3187 3585
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http://mips.gsf.de/staff/pagel

Petr Pikal

2007-Feb-20 06:00 UTC

head link

[R] categorical column to numeric column

Hi

On 19 Feb 2007 at 9:11, Duncan Murdoch wrote:

Date sent:      	Mon, 19 Feb 2007 09:11:52 -0500
From:           	Duncan Murdoch <murdoch at stats.uwo.ca>
To:             	Shubha Vishwanath Karanth <shubhak at ambaresearch.com>
Copies to:      	r-help <R-help at stat.math.ethz.ch>
Subject:        	Re: [R] categorical column to numeric column
> On 2/19/2007 8:36 AM, Shubha Vishwanath Karanth wrote:
> > Hi R,
> > 
> >  
> > 
> > Let 'dd' be a data frame given as:
> > 
> >  
> > 
> >
dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))
> > 
> >  
> > 
> > Now I want to create a column 'g' such that if dd$aa=a then
dd$g=1
> > else dd$g= -1 .
> > 
> >  
> > 
> > So, I gave the below syntax:
> > 
> >  
> > 
> > if((dd$aa)=="a") dd$g=1 else dd$g= -1
> 
> if() looks at just the first entry; it's designed for flow of control
> rather than vectorized calculations.  You want ifelse():
> 
> ifelse( dd$aa == "a", 1, -1)
Another approach is to use the fact that logical vector can be 
interpreted as 1 and 0 vector

(dd$a=="a")*2-1

HTH
Petr

> 
> Duncan Murdoch
> >  
> > 
> > But I get the error message as:
> > 
> > Warning message: 
> > 
> > the condition has length > 1 and only the first element will be
used
> > in: if ((dd$aa) == "a") dd$g = 1 else dd$g = -1 
> > 
> >  
> > 
> > and dd> > 
> >  
> > 
> >> dd
> > 
> >   aa bb g
> > 
> > 1  a  1 1
> > 
> > 2  a  1 1
> > 
> > 3  b  1 1
> > 
> > 4  a  2 1
> > 
> > 5  b  3 1
> > 
> > 6  b  4 1
> > 
> >> 
> > 
> >  
> > 
> > Please let me know what is the error I am doing?
> > 
> >  
> > 
> >  
> > 
> >  
> > 
> >  
> > 
> > 
> > 	[[alternative HTML version deleted]]
> > 
> > ______________________________________________
> > 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.
> 
> ______________________________________________
> 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.
Petr Pikal
petr.pikal at precheza.cz

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