On Mon, Dec 15, 2014 at 10:06 AM, David L Carlson wrote:
> Actually there are not so many matrices as you suggest.
>
> > comb <- combn(28, 4)
> > dim(comb)
> [1] 4 20475
> > sum(comb[1,]==1)
> [1] 2925
> > comb[, 1]
> [1] 1 2 3 4
>
> There are 20,475 combinations, but you cannot choose any fo
ohn McKown
Sent: Monday, December 15, 2014 9:23 AM
To: Kathryn Lord
Cc: r-help
Subject: Re: [R] create matrices with constraint
On Fri, Dec 12, 2014 at 11:00 AM, Kathryn Lord
wrote:
> Dear all,
>
> Suppose that I have natural numbers 1 through 28.
>
> Based on these numbers, choose 4
On Fri, Dec 12, 2014 at 11:00 AM, Kathryn Lord
wrote:
> Dear all,
>
> Suppose that I have natural numbers 1 through 28.
>
> Based on these numbers, choose 4 numbers 7 times without replacement and
> make a 4 by 7 matrix, for example,
>
>
After a relaxing weekend, it came to me that these 4x7 mat
On Sun, Dec 14, 2014 at 9:30 AM, Gerrit Draisma wrote:
> Ha John,
> Sorry I did not follow the discussion but what
> about
> combn(1:28,4)
> ?
> Gerrit.
Very nice! Thanks. The form needed by the OP would be t(combn(1:28,4)) to
swap rows & columns.
I'm cross posting this to the r-help so tha
On Fri, Dec 12, 2014 at 1:45 PM, John McKown
wrote:
>
>
> Hum. Consider the set of all possible unique 4 value vectors in which the
> values in the vectors are taken, without replacement, from the numbers 1
> through 28. This is a mathematical concept called "combination". In this
> case,
I think you might be looking for incomplete block designs. See
Cochran and Cox 1957, page 481
for Plan 11.38
t=28, k=4, r=9, b=63, lambda=1, E=.78. Type I
This design might be the set of 4 x 7 matrices you are looking for.
On Fri, Dec 12, 2014 at 12:00 PM, Kathryn Lord
wrote:
> Dear all,
>
> Su
On Fri, Dec 12, 2014 at 12:17 PM, peter dalgaard wrote:
>
> > On 12 Dec 2014, at 18:00 , Kathryn Lord
> wrote:
> >
> > Dear all,
> >
> > Suppose that I have natural numbers 1 through 28.
> >
> > Based on these numbers, choose 4 numbers 7 times without replacement and
> > make a 4 by 7 matrix, fo
> On 12 Dec 2014, at 18:00 , Kathryn Lord wrote:
>
> Dear all,
>
> Suppose that I have natural numbers 1 through 28.
>
> Based on these numbers, choose 4 numbers 7 times without replacement and
> make a 4 by 7 matrix, for example,
>
>> a1
> [,1] [,2] [,3] [,4] [,5] [,6] [,7]
> [1,]1
Dear all,
Suppose that I have natural numbers 1 through 28.
Based on these numbers, choose 4 numbers 7 times without replacement and
make a 4 by 7 matrix, for example,
> a1
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]159 13 17 21 25
[2,]26 10 14 18 22 26
[3,
9 matches
Mail list logo
