[R] extracting rows and columns from a big matrix

Petr Savicky savicky at cs.cas.cz
Mon Jul 16 17:14:56 CEST 2012

On Mon, Jul 16, 2012 at 03:10:22PM +0200, A J wrote:
> Yes, I have tried it and this works.
> Indeed, if I use a small number of colums, all the methods proposed here are working. Following the previous mail I have splited the number of colums in 4 parts of 447 colums each one. The first and the second ones work weel, but this doesn't occur with third and fourth parts. I am convinced it's not a problem with quotes, because I tried to remove them, and again the code in first and second part worked well. Now I have copied all labels directly from original matrix in txt file not to have any other mistakes. I will inform you about the enigmatic problem when I find it (I hope so...).


According to your first email, the matrices are read from a text file.
If the column/row names work in some parts, but not in other, then
a possible cause can be that the text file contains the names in a form,
which you do not expect. There may be a difference in case of the
letters (names are case sensitive) or there may be white space in the
names. Look at these names, they may be extracted using ?dimnames.

Hope this helps.

Petr Savicky.

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