-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Iasonas Lamprianou
Sent: Wednesday, December 01, 2010 4:52 AM
To: Michael Bedward; ivan.calandra at uni-hamburg.de; Rhelp
Subject: Re: [R] missing values
thank you, I'll have a go and let you know if i have problems
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
----- Original Message ----
From: Michael Bedward <michael.bedward at gmail.com>
To: ivan.calandra at uni-hamburg.de; lamprianou at yahoo.com; Rhelp
<r-help at r-project.org>
Sent: Wed, 1 December, 2010 11:40:13
Subject: Re: [R] missing values
And just to add to Ivan's comment, if you are using the rowSums or
colSums functions with a matrix or data.frame they also have the na.rm
argument.
Michael
On 1 December 2010 20:16, Ivan Calandra <ivan.calandra at uni-hamburg.de> wrote:
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 ?crit :
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