On Aug 28, 2011, at 5:09 PM, marco wrote:
Hi everyone,
have a small problem trying to converting a dataset in matrix form
to an
array.
Specifically: data include 3D measurement -x,y,z of 59 points in 36
objects.
They are stored as a matrix (x) of 2124 rows and 3 columns.
What I want to do is to extract each subject's dataset using an
array (b).
Accordingly, I tried the following command:
b<-array(a,c(59,3,36)).
The problem is that the resulting array for some strange reason
change the
order of the original data.
Not for a "strange reason". The 59 elements in b in column-1 would be
the same in both , but you don't seem to realize that the 60th through
the 118th elements in your original matrix were also all in the x-
column. You have now effectively moved those values to what you were
thinking to use as the y-column.
Specifically, I noticed that, for example, in the first subject, the
x y z
values of the first point are the x values of the first 3 subjects.
You should have kept the last dimension the same and redimension the
object/points indexing by factoring the 2124 rows into what will
become columns and row and leave the xyz coordinates "at the end". I
think that redimensioning as b<-array(a,c(59, 36, 3)) would have re-
folded it sensiblyly. So the b[n,m,] call would retrieve xyz-
coordinates from the n-th point of the m-th object.
Did I perhaps missed something?
Thanks in advance
--
View this message in context:
http://r.789695.n4.nabble.com/converting-matrix-in-array-tp3775025p3775025.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@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.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@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.
