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matrix with fix number columns but variable number rows

6 messages · Francisco J Molina, Uwe Ligges, Sven Garbade +2 more

#
I have to store a number of vectors of the same length. I know the
length but I do not know the number of vectors.

How can I store them as they are created (they are created one by one)?
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#
Francisco J Molina wrote:
*Please* read "An Introduction to R"!

rbind() and indexing a matrix M[i, j] are possible solutions.

Uwe Ligges
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#
Francisco J Molina wrote:

            
Maybe

data <- vector(mode="numeric")
# and here functions, loops  or whatever to read the data
newdata <- datafromanywhere
data <- rbind(data, newdata)

Regards, Sven




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#
If the vectors are created within a loop,

matriz <- NULL
for(...){
 ...
 matriz <- cbind(matriz,vector)
}
matriz

but I think that it's better to define matriz with a large
number of cols and avoid growing the matrix within the
loop:

matriz <- matrix(NULL,nrow=numlineas,ncol=maxnumcols)
col <- 0
for(...){ 
 col <- col+1
 ... 
 matriz[,col] <- vector
}
matriz <- matriz[,1:col] #keep only the used cols
matriz

..and even better if you can avoid the loop, R offers
many opportunities for that.



Dr. Agustin Lobo
Instituto de Ciencias de la Tierra (CSIC)
Lluis Sole Sabaris s/n
08028 Barcelona SPAIN
tel 34 93409 5410
fax 34 93411 0012
alobo at ija.csic.es
On Mon, 18 Mar 2002, Francisco J Molina wrote:

            
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#
On Tue, 19 Mar 2002, Agustin Lobo wrote:

            
Actually I had not tried it, it should be, i.e.

matriz <- matrix(0,nrow=numlineas,ncol=maxnumcols)

as with NULL we cannot fill a matrix

Agus


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8 days later
#
Is that you mean?

X<-cbind(c(10,12,13,11),c(20,25,24,22),c(50,45,54,58))
[1] 4 3

Best, isaia.
Francisco J Molina wrote:

            
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