R help - May 2005 - a more elegant approach to getting the majority level

Hi, I have a factor and I would like to find the most frequent level.

I think my current approach is a bit long winded and I was wondering if
there was a more elegant way to do it:

x <- factor(sample(1:0, 5,replace=TRUE))

levels(x)[ which( as.logical((table(x) == max(table(x)))) == TRUE ) ]

(The length of x will always be an odd number, so I wont get a tie in
max())

Thanks,

-------------------------------------------------------------------
Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
-------------------------------------------------------------------
Alcohol, an alternative to your self
- 'Alcohol' by the Bare Naked Ladies

Don't know if this is more elegant:

names(which.max(table(x)))

Andy
> From: Rajarshi Guha
> 
> Hi, I have a factor and I would like to find the most frequent level.
> 
> I think my current approach is a bit long winded and I was 
> wondering if
> there was a more elegant way to do it:
> 
> x <- factor(sample(1:0, 5,replace=TRUE))
> 
> levels(x)[ which( as.logical((table(x) == max(table(x)))) == TRUE ) ]
> 
> (The length of x will always be an odd number, so I wont get a tie in
> max())
> 
> Thanks,
> 
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
> GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
> -------------------------------------------------------------------
> Alcohol, an alternative to your self
> - 'Alcohol' by the Bare Naked Ladies
> 
> ______________________________________________
> 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
> 
> 
>

Rajarshi Guha wrote:
> Hi, I have a factor and I would like to find the most frequent level.
> 
> I think my current approach is a bit long winded and I was wondering if
> there was a more elegant way to do it:
> 
> x <- factor(sample(1:0, 5,replace=TRUE))
> 
> levels(x)[ which( as.logical((table(x) == max(table(x)))) == TRUE ) ]
(== TRUE) can ALWAYS be omitted, see also:
  library(fortunes)
  fortune("TRUE")

x == max(x) should be replaced by which.max(x)

as.logical() is superfluous


Hence we get:
   names(which.max(table(x)))

Uwe Ligges


> (The length of x will always be an odd number, so I wont get a tie in
> max())
> 
> Thanks,
> 
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
> GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
> -------------------------------------------------------------------
> Alcohol, an alternative to your self
> - 'Alcohol' by the Bare Naked Ladies
> 
> ______________________________________________
> 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

you could try this:

x <- factor(sample(letters[1:3], 20, TRUE))
#######
tab <- table(x)
names(tab)[tab == max(tab)]


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: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Rajarshi Guha" <rxg218 at psu.edu>
To: "R" <r-help at stat.math.ethz.ch>
Sent: Thursday, May 26, 2005 4:36 PM
Subject: [R] a more elegant approach to getting the majority level

> Hi, I have a factor and I would like to find the most frequent 
> level.
>
> I think my current approach is a bit long winded and I was wondering 
> if
> there was a more elegant way to do it:
>
> x <- factor(sample(1:0, 5,replace=TRUE))
>
> levels(x)[ which( as.logical((table(x) == max(table(x)))) == 
> TRUE ) ]
>
> (The length of x will always be an odd number, so I wont get a tie 
> in
> max())
>
> Thanks,
>
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
> GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
> -------------------------------------------------------------------
> Alcohol, an alternative to your self
> - 'Alcohol' by the Bare Naked Ladies
>
> ______________________________________________
> 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
>

You could also use:
> names(rev(sort(table(x))))[1]
There is nonetheless a difference if there are several levels which
provides this maximum.
This method will only return one, yours would return all those levels
(which may not be desirable for some others processing).

HTH,

Eric

Eric Lecoutre
UCL /  Institut de Statistique
Voie du Roman Pays, 20
1348 Louvain-la-Neuve
Belgium

tel: (+32)(0)10473050
lecoutre at stat.ucl.ac.be
http://www.stat.ucl.ac.be/ISpersonnel/lecoutre

If the statistics are boring, then you've got the wrong numbers. -Edward
Tufte   

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Rajarshi Guha
> Sent: jeudi 26 mai 2005 16:37
> To: R
> Subject: [R] a more elegant approach to getting the majority level
> 
> 
> Hi, I have a factor and I would like to find the most frequent level.
> 
> I think my current approach is a bit long winded and I was 
> wondering if there was a more elegant way to do it:
> 
> x <- factor(sample(1:0, 5,replace=TRUE))
> 
> levels(x)[ which( as.logical((table(x) == max(table(x)))) == TRUE ) ]
> 
> (The length of x will always be an odd number, so I wont get a tie in
> max())
> 
> Thanks,
> 
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
> GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
> -------------------------------------------------------------------
> Alcohol, an alternative to your self
> - 'Alcohol' by the Bare Naked Ladies
> 
> ______________________________________________
> 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
>

The which.max solution is fine as long as the maximum is always unique.
Otherwise, which.max will give you the first maximum.

So using the "x == max(x) " version will have an advantage if there
can be
ties.

Regards,

Matt Wiener

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Uwe Ligges
Sent: Thursday, May 26, 2005 10:57 AM
To: rxg218 at psu.edu
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] a more elegant approach to getting the majority level


Rajarshi Guha wrote:
> Hi, I have a factor and I would like to find the most frequent level.
> 
> I think my current approach is a bit long winded and I was wondering if
> there was a more elegant way to do it:
> 
> x <- factor(sample(1:0, 5,replace=TRUE))
> 
> levels(x)[ which( as.logical((table(x) == max(table(x)))) == TRUE ) ]
(== TRUE) can ALWAYS be omitted, see also:
  library(fortunes)
  fortune("TRUE")

x == max(x) should be replaced by which.max(x)

as.logical() is superfluous


Hence we get:
   names(which.max(table(x)))

Uwe Ligges


> (The length of x will always be an odd number, so I wont get a tie in
> max())
> 
> Thanks,
> 
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
> GPG Fingerprint: 0CCA 8EE2 2EEB 25E2 AB04 06F7 1BB9 E634 9B87 56EE
> -------------------------------------------------------------------
> Alcohol, an alternative to your self
> - 'Alcohol' by the Bare Naked Ladies
> 
> ______________________________________________
> 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

______________________________________________
R-help at stat.math.ethz.ch mailing list
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PLEASE do read the posting guide!
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