[R] Avoiding FOR loops

dxc13 dxc13 at health.state.ny.us
Mon Jan 7 01:55:31 CET 2008


useR's,

I would like to know if there is a way to avoid using FOR loops to perform
the below calculation. 

Consider the following data:

> x
     [,1] [,2] [,3]
[1,]    4   11    1
[2,]    1    9    2
[3,]    7    3    3
[4,]    3    6    4
[5,]    6    8    5

> xk
     Var1  Var2 Var3
1   -0.25  1.75  0.5
2    0.75  1.75  0.5
3    1.75  1.75  0.5
4    2.75  1.75  0.5
5    3.75  1.75  0.5
6    4.75  1.75  0.5
7    5.75  1.75  0.5
8    6.75  1.75  0.5
9    7.75  1.75  0.5
10  -0.25  2.75  0.5

Here, X is a matrix of 3 variables in which each is of size 5 and XK are
some values that correspond to each variable.  For each variable, I want to
do:

|Xi - xkj|   where i = 1 to 3 and j = 1 to 10

It looks as if a double FOR loop would work, but can the apply function
work?  Or some other function that is shorter than a FOR loop?  Thank you, I
hope this makes sense.

Derek


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