[R] missing values

[Ivan Calandra]

Hi,

(a) sum() and mean() have a na.rm argument that should be set to TRUE.

(b) let's try with an example:
x <- c(1:5, NA, NA, 6:10, NA)
x[is.na(x)] <- 0  ## replace NAs by 0

HTH,
Ivan


Le 12/1/2010 10:00, Iasonas Lamprianou a écrit :
> Dear all,
> i have spent a lot of time trying to solve this problem, but I am sure that
> there must be a simple solution. So, as a last resort, I am coming back to you
> again. I have a dataset with some (almost random) values in many variables. Lets
> say that the dataset represents the scores of students to test questions. What I
> need to do is to sum the scores for each student. However, wherever there is a
> missing (NA) value, I cannot get the total score.  How can I compute the total
> score and the average per question (a) by ignoring the missing responses, (b) by
> assuming that a missing response is a zero?
> Thank you for the response
>
>
>   Dr. Iasonas Lamprianou
>
>
>
>
> Assistant Professor (Educational Research and Evaluation)
> Department of Education Sciences
> European University-Cyprus
> P.O. Box 22006
> 1516 Nicosia
> Cyprus
> Tel.: +357-22-713178
> Fax: +357-22-590539
>
>
>
>
> Honorary Research Fellow
> Department of Education
> The University of Manchester
> Oxford Road, Manchester M13 9PL, UK
> Tel. 0044  161 275 3485
> iasonas.lamprianou at manchester.ac.uk
>
>
>
>
>
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>

-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra at uni-hamburg.de

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