[R] sorting a matrix by a different colnames order

[jim holtman]

> mx = matrix(rnorm(1:20),5,4)
> colnames(mx) = letters[1:4]
> rownames(mx) = letters[1:5]
> mx
           a          b          c           d
a -0.6264538 -0.8204684  1.5117812 -0.04493361
b  0.1836433  0.4874291  0.3898432 -0.01619026
c -0.8356286  0.7383247 -0.6212406  0.94383621
d  1.5952808  0.5757814 -2.2146999  0.82122120
e  0.3295078 -0.3053884  1.1249309  0.59390132
> (new.col.names = sample(letters[1:4]))
[1] "d" "b" "c" "a"
> mx[, new.col.names]
            d          b          c          a
a -0.04493361 -0.8204684  1.5117812 -0.6264538
b -0.01619026  0.4874291  0.3898432  0.1836433
c  0.94383621  0.7383247 -0.6212406 -0.8356286
d  0.82122120  0.5757814 -2.2146999  1.5952808
e  0.59390132 -0.3053884  1.1249309  0.3295078
>


On 2/7/07, portnoy at supereva.it <portnoy at supereva.it> wrote:
> Hi R users,
> I would like to know how to sort a matrix according a different order of
> colnames (or rownames) ,e.g.,
> mx = matrix(rnorm(1:20),5,4)
> colnames(mx) = letters[1:4]
> rownames(mx) = letters[1:5]
> mx
>             a          b          c           d
> a  0.02362598 -0.7033460  0.8106089 -1.03456219
> b -0.45021522 -1.5769522  0.1770634  0.27997249
> c  1.34732392  0.2956623  2.0027231 -0.85321627
> d  0.82314457  1.2698347 -0.5468151  0.05806375
> e -0.18668401 -0.4210383  0.6263465 -0.18889031
>
> (new.col.names = sample(letters[1:4]))
> [1] "a" "b" "d" "c"
>
> so the new matrix has to be ordered according the new.col.names,i.e.,
>             a          b           d          c
> a  0.02362598 -0.7033460        -1.03456219  0.8106089
> b -0.45021522 -1.5769522         0.27997249  0.1770634
> c  1.34732392  0.2956623        -0.85321627  2.0027231
> d  0.82314457  1.2698347         0.05806375 -0.5468151
> e -0.18668401 -0.4210383        -0.18889031  0.6263465
>
> Hope this is not a "basic question"
>
> Thank you for your help.
>
> Paolo
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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