On Dec 11, 2014, at 4:38 PM, Kathryn Lord wrote:
Dear R users,
I'd like to make 4 by 7 matrices as many as possible with natural numbers 1
through 28 such that each matrix have different elements of each column.
I was tempted to respond:
We're very sorry. The Soduko Challenge Contest was closed several years ago.
For example,
simply here is one
a1 - matrix(1:28, 4,7)
a1
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]159 13 17 21 25
[2,]26 10 14 18 22 26
[3,]37 11 15 19 23 27
[4,]48 12 16 20 24 28
another one
a2 - matrix(1:28, 4,7, byrow=T)
a2
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]1234567
[2,]89 10 11 12 13 14
[3,] 15 16 17 18 19 20 21
[4,] 22 23 24 25 26 27 28
What about:
replicate(1000, list(matrix(sample(28), 4,7) ) )
Somebody ( but not me) will probably know the probability that each matrix has
different elements of each column once you explain exactly what that phrase
means to you. At the moment its not clear if a permutation of columns makes a
matrix different.
Matrices a1 and a2 have different columns, and I guess there are such many
matrices.
Any suggestion will be greatly appreciated.
Best,
Kathryn Lord
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David Winsemius
Alameda, CA, USA
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