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Student Support Forum: 'Help with creating matrix from another matrix' topicStudent Support Forum > General > Archives > "Help with creating matrix from another matrix"

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Author Comment/Response
Bill Simpson
04/12/13 00:35am

In Response To 'Re: Re: Re: Re: Re: Re: Re: Re: Help with creat...'
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I will only compute two rows here to show.

In[2]:= c = Table[
xp = Map[Last, Position[a[[y]], x]];
yp = Map[Last, Position[a[[y]], y]];
m = Min[Length[xp], Length[yp]];
xp = Take[xp, m]; yp = Take[yp, m];
If[xp=={} || yp=={} || Length[xp]!=Length[yp], 0,
Plus@@Map[b[[Sequence@@#]]&, Transpose[{yp, xp}]]], {y, 2}, {x, 150}]

Out[2]= {{b[[1, 1]], b[[1, 2]], b[[1, 3]], b[[1, 4]], b[[1, 5]], b[[1, 6]], b[[1, 10]], b[[1, 11]], b[[1, 12]], b[[1, 7]], b[[1, 8]], b[[1, 9]], 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, b[[1, 13]], b[[1, 14]], b[[1, 15]], b[[1, 16]], b[[1, 17]], b[[1, 18]], b[[1, 22]], b[[1, 23]], b[[1, 24]], b[[1, 19]], b[[1, 20]], b[[1, 21]], 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}

To compute the first row of matrix c I will look for 1 and x in the first row of matrix a.

There is a 1 in the first row of matrix a and so I can compute matrix c[1,x].

Is the first row of matrix c correct now?

To compute the second row of matrix c I will look for 2 and x in the second row of matrix a.

There is no 2 in the second row of matrix a and so I cannot compute c[2,x] for matrix c and the result is all zero for the second row of matrix c. This is in error.

I will guess a change.

To compute the second row of matrix c I will look for 2 and x in the first and second row of matrix a.

In[3]:= c = Table[
xp = Map[Last, Position[Take[a, y], x]];
yp = Map[Last, Position[Take[a, y], y]];
m = Min[Length[xp], Length[yp]];
xp = Take[xp, m]; yp = Take[yp, m];
If[xp=={} || yp=={} || Length[xp]!=Length[yp], 0,
Plus@@Map[b[[Sequence@@#]]&, Transpose[{yp, xp}]]], {y, 2}, {x, 150}]

Out[3]= {{b[[1, 1]], b[[1, 2]], b[[1, 3]], b[[1, 4]], b[[1, 5]], b[[1, 6]], b[[1, 10]], b[[1, 11]], b[[1, 12]], b[[1, 7]], b[[1, 8]], b[[1, 9]], 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, b[[1, 13]], b[[1, 14]], b[[1, 15]], b[[1, 16]], b[[1, 17]], b[[1, 18]], b[[1, 22]], b[[1, 23]], b[[1, 24]], b[[1, 19]], b[[1, 20]], b[[1, 21]], 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{b[[2, 1]], b[[2, 2]], b[[2, 3]], b[[2, 4]], b[[2, 5]], b[[2, 6]], b[[2, 10]], b[[2, 11]], b[[2, 12]], b[[2, 7]], b[[2, 8]], b[[2, 9]], b[[2, 10]], b[[2, 11]], b[[2, 12]], b[[2, 7]], b[[2, 8]], b[[2, 9]], 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, b[[2, 13]], b[[2, 14]], b[[2, 15]], b[[2, 16]], b[[2, 17]], b[[2, 18]], b[[2, 22]], b[[2, 23]], b[[2, 24]], b[[2, 19]], b[[2, 20]], b[[2, 21]], b[[2, 22]], b[[2, 23]], b[[2, 24]], b[[2, 19]], b[[2, 20]], b[[2, 21]], 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}

This second row is not all zero and I believe some is correct, but it is still in error.

I do not know how to ask you a question that you will understand. You do not know how to tell me an answer that I will understand.

For your last question to transform code into Mathematica I do not know what S[k] is.

Perhaps this will help you

B = Table[0, {150}, {150}];
For[k = 1, k <= 16, k++,
Table[If[i <= j,
B[[i, j]] = B[[i, j]] + A[[Position[S[k], i], Position[S[k], j]]]], {i, S[k]}, {j, S[k]}]
]

but I cannot test this for you because I do not have information to understand this.

URL: ,

Subject (listing for 'Help with creating matrix from another matrix')
Author Date Posted
Help with creating matrix from another matrix Anton Siswo 03/24/13 01:15am
Re: Help with creating matrix from another matrix Bill Simpson 03/24/13 11:53pm
Re: Re: Help with creating matrix from another ... Anton Siswo 03/25/13 11:35am
Re: Re: Re: Help with creating matrix from anot... Bill Simpson 03/25/13 7:32pm
Re: Re: Re: Help with creating matrix from anot... Bill Simpson 03/25/13 10:20pm
Re: Re: Re: Re: Help with creating matrix from ... Anton Siswo 03/31/13 7:22pm
Re: Re: Re: Re: Re: Help with creating matrix f... Bill Simpson 04/01/13 00:06am
Re: Re: Re: Re: Re: Re: Help with creating matr... Anton Siswo 04/01/13 5:52pm
Re: Re: Re: Re: Re: Help with creating matrix f... Bill Simpson 04/01/13 10:44am
Re: Re: Re: Re: Re: Re: Help with creating matr... Anton Siswo 04/08/13 04:52am
Re: Re: Re: Re: Re: Re: Re: Help with creating ... Bill Simpson 04/09/13 8:35pm
Re: Re: Re: Re: Re: Re: Re: Re: Help with creat... Anton Siswo 04/11/13 10:58am
Re: Re: Re: Re: Re: Re: Re: Help with creating ... Bill Simpson 04/09/13 9:54pm
Re: Re: Re: Re: Re: Re: Re: Re: Help with creat... Anton Siswo 04/10/13 9:41pm
Re: Re: Re: Re: Re: Re: Re: Re: Re: Help with c... Bill Simpson 04/12/13 00:35am
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Help wi... Anton Siswo 04/16/13 07:19am
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Hel... Bill Simpson 04/16/13 7:48pm
Re: Help with creating matrix from another matrix Anton Siswo 03/26/13 11:29pm
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