R help - Feb 2008 - counts of each column that are not NA, and/or greater than column means

Hi,

Given a test matrix, test <- matrix(c(1,2,3,NA,2,3,NA,NA,2), 3,3)

A) How to compute the counts of each column (excluding the NA) i.e., 3, 2, 1

B) How to compute the counts of each column (excluding the NA) that are
greater than the column means ? i.e., 1, 1, 0

I could write a for loop, but hope to use better alternative.

	[[alternative HTML version deleted]]

On Mon, Feb 04, 2008 at 03:21:10PM +0800, Ng Stanley
wrote:
> Hi,
> 
> Given a test matrix, test <- matrix(c(1,2,3,NA,2,3,NA,NA,2), 3,3)
> 
> A) How to compute the counts of each column (excluding the NA) i.e., 3, 2,
1
apply(test, 2, function(x) sum(!is.na(x)))
> B) How to compute the counts of each column (excluding the NA) that are
> greater than the column means ? i.e., 1, 1, 0
apply(test, 2, function(x) sum(x > mean(x, na.rm=TRUE), na.rm=TRUE))

In general, you need ?apply to calculate something for each row/column
of a matrix.

Gabor
> I could write a for loop, but hope to use better alternative.
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.
-- 
Csardi Gabor <csardi at rmki.kfki.hu>    UNIL DGM

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check the following options:

test <- matrix(c(1,2,3,NA,2,3,NA,NA,2), 3, 3)

# A
colSums(!is.na(test))

# B
mat <- test > rep(colMeans(test, na.rm = TRUE), each = nrow(test))
colSums(!is.na(mat) & mat)

apply(test, 2, function(x) {
     mus <- mean(x, na.rm = TRUE)
     sum(x > mus, na.rm = 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


Quoting Ng Stanley <stanleyngkl at gmail.com>:
> Hi,
>
> Given a test matrix, test <- matrix(c(1,2,3,NA,2,3,NA,NA,2), 3,3)
>
> A) How to compute the counts of each column (excluding the NA) i.e., 3, 2,
1
>
> B) How to compute the counts of each column (excluding the NA) that are
> greater than the column means ? i.e., 1, 1, 0
>
> I could write a for loop, but hope to use better alternative.
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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

Gabor Csardi wrote:
>On Mon, Feb 04, 2008 at 03:21:10PM +0800, Ng Stanley wrote:
>  
>
>>Hi,
>>
>>Given a test matrix, test <- matrix(c(1,2,3,NA,2,3,NA,NA,2), 3,3)
>>
>>A) How to compute the counts of each column (excluding the NA) i.e., 3,
2, 1
>>    
>>
>
>apply(test, 2, function(x) sum(!is.na(x)))
>  
>
or more efficiently:

colSums(!is.na(test))

Patrick Burns
patrick at burns-stat.com
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")
>  
>
>>B) How to compute the counts of each column (excluding the NA) that are
>>greater than the column means ? i.e., 1, 1, 0
>>    
>>
>
>apply(test, 2, function(x) sum(x > mean(x, na.rm=TRUE), na.rm=TRUE))
>
>In general, you need ?apply to calculate something for each row/column
>of a matrix.
>
>Gabor
>
>  
>
>>I could write a for loop, but hope to use better alternative.
>>
>>	[[alternative HTML version deleted]]
>>
>>______________________________________________
>>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.
>>    
>>
>
>  
>