# [R] "apply" question

Dimitris Rizopoulos dimitris.rizopoulos at med.kuleuven.ac.be
Mon May 2 17:13:32 CEST 2005

```you could try something like this:

dat <- rbind(c(1, 2, 5, 2, 3, NA, 5, NA, 1, 4),
c(3, 1, 4, 5, 2, 6, NA, 4, NA, 1))
##########
# (1)
rowSums(is.na(dat[, 6:10]))

## (2)
dat. <- dat[, 1:5]
dat.[is.na(dat[, 6:10])] <- NA
rowSums(dat., na.rm=TRUE)
rowMeans(dat., na.rm=TRUE)

I hope it helps.

Best,
Dimitris

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

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: "Christoph Scherber" <Christoph.Scherber at uni-jena.de>
To: <r-help at stat.math.ethz.ch>
Sent: Monday, May 02, 2005 4:52 PM
Subject: [R] "apply" question

> Dear R users,
>
> I´ve got a simple question but somehow I can´t find the solution:
>
> I have a data frame with columns 1-5 containing one set of integer
> values, and columns 6-10 containing another set of integer values.
> Columns 6-10 contain NA´s at some places.
>
> I now want to calculate
> (1) the number of values in each row of columns 6-10 that were NA´s
> (2) the sum of all values on columns 1-5 for which there were no
> missing values in the corresponding cells of columns 6-10.
>
>
> Example: (let´s call the data frame "data")
>
> Col1   Col2   Col3   Col4   Col5   Col6   Col7   Col8   Col9   Col10
> 1      2      5      2      3      NA      5      NA    1      4
> 3      1      4      5      2      6      NA      4     NA     1
>
> The result would then be (for the first row)
> (1) "There were 2 NA´s in columns 6-10."
> (2) The mean of Columns 1-5 was 2+2+3=7" (because there were NA´s in
> the 1st and 3rd position in rows 6-10)
>
> So far, I know how to calculate the rowSums for the data.frame, but
> I don´t know how to condition these on the values of columns 6-10
>
> rowSums(data[,1:5]) #that´s straightforward
> apply(data[,6:19],1,function(x)sum(is.na(x))) #this also works fine
>
> But I don´t know how to select just the desired values of columns
> 1-5 (as described above)
>
>
> Can anyone help me? Thanks a lot in advance!
>
> Best regards
> Christoph
>
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