CODEWITHSUNDEEP
rfunctionstructure
wen
wen

Reputation: 1935

So confused over structure() in R

I was looking at R-help on structure(). The example given by the help file is this:

structure(1:6, dim=2:3)
     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6

which creates a very nice 2 by 3 matrix. However, when I tried 

structure(1:8, dim=2:4)

It won't work. Why? Another question is when should I use this structure() function? I don't understand why we need it, since we have matrix() and data.frame() etc.

Upvotes: 1

Views: 64

Answers (2)

codeola
codeola

Reputation: 838

The reason your code doesn't work is because 2:4 yields (2,3,4). You want c(2,4) if you want a 2x4 matrix. That said, using structure to set attributes on a vector to turn in into a matrix is a really odd way of doing that. structure does nothing more than return a copy of the object with additional/modified attributes, in your case exploiting the fact that R represents matrices as vectors with a dim attribute.

Upvotes: 4

IRTFM
IRTFM

Reputation: 263441

If you want an array then use the 'array' function.

array(1:8, dim=2:4)

There are not many times when a beginner in R needs 'structure'.

Upvotes: 0

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