[R] Skipping rows and columns in large matrix

[Gabor Grothendieck]

Columns that correspond to NULLs in the colClasses arg of read.table
are ignored.  ?read.table

On 5/8/07, Silvia Lomascolo <slomascolo at zoo.ufl.edu> wrote:
>
> I work on Windows, R version 2.4.1
> I need to leave out many rows and columns when reading a matrix.  The 'skip'
> commands in read.table, seem to be just for skipping rows, if I understand
> well, but I need to skip many columns as well. I tried something very simple
> and left one row and one column out, but I don't know how to do it for many
> rows and columns at a time.
>
> Example:
>
> zzz # euclidean distances matrix
>
>      X1   X2   X3   X4   X5
> X1    0   11   12     1   15
> X2   11    0     5   12     3
> X3   12    5     0     8     4
> X4     1  12     8     0   16
> X5   15    3     4    16    0
>
> skip.data = zzz [-3, -3]   #  gives me the same matrix without row 3 and
> column 3... how can I tell R to skip more than one row and column?  Columns
> and rows to be left out are not contiguous  The matrix I'm using is fairly
> large (335x335), so excel won't read the whole thing, and it's not a
> fixed-width txt file, so I cannot use read.fwf.  I also don't have access to
> Unix, as was suggested to other users to solve this problem.
>
>
> --
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