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Shoaaib Mehmood

2007-Nov-16 10:21 UTC

[R] sorting factor levels by data frequency of levels

using an example from r online help
> state <- c("tas", "sa", "qld",
"nsw", "nsw", "nt", "wa",
"wa",    "qld", "vic", "nsw", "vic",
"qld", "qld", "sa", "tas",
    "sa", "nt", "wa", "vic",
"qld", "nsw", "nsw", "wa",
    "sa", "act", "nsw", "vic",
"vic", "act")>statefac<-factor(state)
now if i use levels function to print factor levels they are shown
sorted by alphabetical order. the output is shown below
>levels(statefac)[1] "act" "nsw" "nt" "qld"
"sa" "tas" "vic" "wa"

I WANT THE FACTOR LEVELS TO BE SORTED IN ORDER OF DESCENDING DATA
FREQUENCY IN EACH LEVEL. IN OTHER WORDS I WANT THE LEVEL WHICH HAS THE
HIGHEST FREQUENCY IN STATE TO APPEAR FIRST, FOLLOWED BY ONE WHICH HAS
THE SECOND HIGHEST FREQUENCY AND SO ON.

Any help will be appreciated


-- 
Regards,
Rana Shoaaib Mehmood

Dimitris Rizopoulos

2007-Nov-16 10:32 UTC

head link

[R] sorting factor levels by data frequency of levels

one way is the following:

tb <- table(state)
statefac <- factor(state,
    levels = names(tb[order(tb, decreasing = TRUE)]))


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Shoaaib Mehmood" <shoaaib at gmail.com>
To: <r-help at stat.math.ethz.ch>; <r-help at r-project.org>
Sent: Friday, November 16, 2007 11:21 AM
Subject: [R] sorting factor levels by data frequency of levels

> using an example from r online help
>
>> state <- c("tas", "sa", "qld",
"nsw", "nsw", "nt", "wa",
"wa",
>    "qld", "vic", "nsw", "vic",
"qld", "qld", "sa", "tas",
>    "sa", "nt", "wa", "vic",
"qld", "nsw", "nsw", "wa",
>    "sa", "act", "nsw", "vic",
"vic", "act")
>>statefac<-factor(state)
>
> now if i use levels function to print factor levels they are shown
> sorted by alphabetical order. the output is shown below
>
>>levels(statefac)
> [1] "act" "nsw" "nt" "qld"
"sa" "tas" "vic" "wa"
>
> I WANT THE FACTOR LEVELS TO BE SORTED IN ORDER OF DESCENDING DATA
> FREQUENCY IN EACH LEVEL. IN OTHER WORDS I WANT THE LEVEL WHICH HAS 
> THE
> HIGHEST FREQUENCY IN STATE TO APPEAR FIRST, FOLLOWED BY ONE WHICH 
> HAS
> THE SECOND HIGHEST FREQUENCY AND SO ON.
>
> Any help will be appreciated
>
>
> -- 
> Regards,
> Rana Shoaaib Mehmood
>
> ______________________________________________
> R-help at 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.
> 

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

john seers (IFR)

2007-Nov-16 14:20 UTC

head link

[R] Scaling a column in groups

Hello R people

I have a column of numeric values that are grouped in blocks of 25 and
to be centered and scaled within each block. (That is subtract the mean
and divide by the standard deviation.) 

Is there a neater way to do this? i.e not using a loop?

Example looped code:

testdata<-1:100
csvalues<-NULL
for (i in 1:(length(testdata)/25)) {
    st<-(i-1) * 25 + 1
    sel<-st:(st+24)
    selvals<-testdata[sel]
    csvalues<-c(csvalues, scale(selvals, scale=sd(selvals)))  
}

Thanks for any help.


John Seers



 
---

John Seers
Institute of Food Research
Norwich Research Park
Colney
Norwich
NR4 7UA
 

tel +44 (0)1603 251497
fax +44 (0)1603 507723
e-mail john.seers at bbsrc.ac.uk                         
e-disclaimer at http://www.ifr.ac.uk/edisclaimer/ 
 
Web sites:

www.ifr.ac.uk   
www.foodandhealthnetwork.com

Gabor Grothendieck

2007-Nov-16 15:12 UTC

head link

[R] Scaling a column in groups

Try this:

c(apply(matrix(testdata, 25), 2, scale))

On Nov 16, 2007 9:20 AM, john seers (IFR) <john.seers at bbsrc.ac.uk>
wrote:>
> Hello R people
>
> I have a column of numeric values that are grouped in blocks of 25 and
> to be centered and scaled within each block. (That is subtract the mean
> and divide by the standard deviation.)
>
> Is there a neater way to do this? i.e not using a loop?
>
> Example looped code:
>
> testdata<-1:100
> csvalues<-NULL
> for (i in 1:(length(testdata)/25)) {
>    st<-(i-1) * 25 + 1
>    sel<-st:(st+24)
>    selvals<-testdata[sel]
>    csvalues<-c(csvalues, scale(selvals, scale=sd(selvals)))
> }
>
> Thanks for any help.
>
>
> John Seers
>
>
>
>
> ---
>
> John Seers
> Institute of Food Research
> Norwich Research Park
> Colney
> Norwich
> NR4 7UA
>
>
> tel +44 (0)1603 251497
> fax +44 (0)1603 507723
> e-mail john.seers at bbsrc.ac.uk
> e-disclaimer at http://www.ifr.ac.uk/edisclaimer/
>
> Web sites:
>
> www.ifr.ac.uk
> www.foodandhealthnetwork.com
>
> ______________________________________________
> R-help at 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.
>

john seers (IFR)

2007-Nov-16 15:27 UTC

head link

[R] Scaling a column in groups

Ah, that is neat.

Thanks.

JS



 -----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: 16 November 2007 15:12
To: john seers (IFR)
Cc: r-help at r-project.org
Subject: Re: [R] Scaling a column in groups

Try this:

c(apply(matrix(testdata, 25), 2, scale))

On Nov 16, 2007 9:20 AM, john seers (IFR) <john.seers at bbsrc.ac.uk>
wrote:>
> Hello R people
>
> I have a column of numeric values that are grouped in blocks of 25 and
> to be centered and scaled within each block. (That is subtract the 
> mean and divide by the standard deviation.)
>
> Is there a neater way to do this? i.e not using a loop?
>
> Example looped code:
>
> testdata<-1:100
> csvalues<-NULL
> for (i in 1:(length(testdata)/25)) {
>    st<-(i-1) * 25 + 1
>    sel<-st:(st+24)
>    selvals<-testdata[sel]
>    csvalues<-c(csvalues, scale(selvals, scale=sd(selvals))) }
>
> Thanks for any help.
>
>
> John Seers
>
>
>
>
> ---
>
> John Seers
> Institute of Food Research
> Norwich Research Park
> Colney
> Norwich
> NR4 7UA
>
>
> tel +44 (0)1603 251497
> fax +44 (0)1603 507723
> e-mail john.seers at bbsrc.ac.uk
> e-disclaimer at http://www.ifr.ac.uk/edisclaimer/
>
> Web sites:
>
> www.ifr.ac.uk
> www.foodandhealthnetwork.com
>
> ______________________________________________
> R-help at 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.
>

Jim Lemon

2007-Nov-17 09:41 UTC

head link

[R] sorting factor levels by data frequency of levels

Shoaaib Mehmood wrote:> using an example from r online help
> 
> 
>>state <- c("tas", "sa", "qld",
"nsw", "nsw", "nt", "wa",
"wa",
> 
>     "qld", "vic", "nsw", "vic",
"qld", "qld", "sa", "tas",
>     "sa", "nt", "wa", "vic",
"qld", "nsw", "nsw", "wa",
>     "sa", "act", "nsw", "vic",
"vic", "act")
> 
>>statefac<-factor(state)
> 
> 
> now if i use levels function to print factor levels they are shown
> sorted by alphabetical order. the output is shown below
> 
> 
>>levels(statefac)
> 
> [1] "act" "nsw" "nt" "qld"
"sa" "tas" "vic" "wa"
> 
> I WANT THE FACTOR LEVELS TO BE SORTED IN ORDER OF DESCENDING DATA
> FREQUENCY IN EACH LEVEL. IN OTHER WORDS I WANT THE LEVEL WHICH HAS THE
> HIGHEST FREQUENCY IN STATE TO APPEAR FIRST, FOLLOWED BY ONE WHICH HAS
> THE SECOND HIGHEST FREQUENCY AND SO ON.
> 
levels(state)<-levels(state)[rev(order(tabulate(state)))]

Jim

Greg Snow

2007-Nov-19 18:18 UTC

head link

[R] Scaling a column in groups

?ave

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of john seers (IFR)
> Sent: Friday, November 16, 2007 7:21 AM
> To: r-help at r-project.org
> Subject: [R] Scaling a column in groups
> 
> 
>  
> Hello R people
> 
> I have a column of numeric values that are grouped in blocks 
> of 25 and to be centered and scaled within each block. (That 
> is subtract the mean and divide by the standard deviation.) 
> 
> Is there a neater way to do this? i.e not using a loop?
> 
> Example looped code:
> 
> testdata<-1:100
> csvalues<-NULL
> for (i in 1:(length(testdata)/25)) {
>     st<-(i-1) * 25 + 1
>     sel<-st:(st+24)
>     selvals<-testdata[sel]
>     csvalues<-c(csvalues, scale(selvals, scale=sd(selvals))) }
> 
> Thanks for any help.
> 
> 
> John Seers
> 
> 
> 
>  
> ---
> 
> John Seers
> Institute of Food Research
> Norwich Research Park
> Colney
> Norwich
> NR4 7UA
>  
> 
> tel +44 (0)1603 251497
> fax +44 (0)1603 507723
> e-mail john.seers at bbsrc.ac.uk                         
> e-disclaimer at http://www.ifr.ac.uk/edisclaimer/ 
>  
> Web sites:
> 
> www.ifr.ac.uk   
> www.foodandhealthnetwork.com
> 
> ______________________________________________
> R-help at 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.
>

Greg Snow

2007-Nov-19 19:32 UTC

head link

[R] sorting factor levels by data frequency of levels

?reorder

Try:
> newstate <- reorder(state,state, length)
Or
> newstate <- reorder(state,state, function(x) -length(x) )
Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Shoaaib Mehmood
> Sent: Friday, November 16, 2007 3:22 AM
> To: r-help at stat.math.ethz.ch; r-help at r-project.org
> Subject: [R] sorting factor levels by data frequency of levels
> 
> using an example from r online help
> 
> > state <- c("tas", "sa", "qld",
"nsw", "nsw", "nt", "wa",
"wa",
>     "qld", "vic", "nsw", "vic",
"qld", "qld", "sa", "tas",
>     "sa", "nt", "wa", "vic",
"qld", "nsw", "nsw", "wa",
>     "sa", "act", "nsw", "vic",
"vic", "act")
> >statefac<-factor(state)
> 
> now if i use levels function to print factor levels they are 
> shown sorted by alphabetical order. the output is shown below
> 
> >levels(statefac)
> [1] "act" "nsw" "nt" "qld"
"sa" "tas" "vic" "wa"
> 
> I WANT THE FACTOR LEVELS TO BE SORTED IN ORDER OF DESCENDING 
> DATA FREQUENCY IN EACH LEVEL. IN OTHER WORDS I WANT THE LEVEL 
> WHICH HAS THE HIGHEST FREQUENCY IN STATE TO APPEAR FIRST, 
> FOLLOWED BY ONE WHICH HAS THE SECOND HIGHEST FREQUENCY AND SO ON.
> 
> Any help will be appreciated
> 
> 
> --
> Regards,
> Rana Shoaaib Mehmood
> 
> ______________________________________________
> R-help at 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.
>

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