I try to utilize some operations on rows in a matrix using command 'apply'
but find a problem.
First I write a simple function to normalize a vector (ignore error
handling) as follows:
normalize = function( v ) {
return( ( v-min(v) ) / ( max(v) - min(v) ) )
}
The function works fine for a vector:
> normalize( 1:5 )
[1] 0.00 0.25 0.50 0.75 1.00
Then I generate a matrix:
> a = c(1:5) %*% t(1:5)
> a
[,1] [,2] [,3] [,4] [,5]
[1,] 1 2 3 4 5
[2,] 2 4 6 8 10
[3,] 3 6 9 12 15
[4,] 4 8 12 16 20
[5,] 5 10 15 20 25
The function works fine upon the columns:
> apply( a, 2, normalize )
[,1] [,2] [,3] [,4] [,5]
[1,] 0.00 0.00 0.00 0.00 0.00
[2,] 0.25 0.25 0.25 0.25 0.25
[3,] 0.50 0.50 0.50 0.50 0.50
[4,] 0.75 0.75 0.75 0.75 0.75
[5,] 1.00 1.00 1.00 1.00 1.00
BUT it does not work upon the rows:
> apply( a, 1, normalize )
[,1] [,2] [,3] [,4] [,5]
[1,] 0.00 0.00 0.00 0.00 0.00
[2,] 0.25 0.25 0.25 0.25 0.25
[3,] 0.50 0.50 0.50 0.50 0.50
[4,] 0.75 0.75 0.75 0.75 0.75
[5,] 1.00 1.00 1.00 1.00 1.00
Can anyone help me to solve this problem? Thanks in advance!
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