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Author Comment/Response
Bill Simpson
03/25/13 7:32pm

In Response To 'Re: Re: Help with creating matrix from another ...'
---------
I need an answer to a question.

I now understand how to do this.

In[1]:= x=49;y=50;
{Map[Last,Position[a,x]],Map[Last,Position[a,y]]}

Out[2]= {{22,13,10,1},{23,14,11,2}}

That lets me calculate this.

In[3]:= Plus@@Map[Part[b,Sequence@@#]&,Transpose[%]]

Out[3]= b[[1,2]]+b[[10,11]]+b[[13,14]]+b[[22,23]]

But if I do this.

In[4]:= x=1;y=7;
{Map[Last,Position[a,x]],Map[Last,Position[a,y]]}

Out[5]= {{1},{10,1}}

then I do not know what to do. 1 appears one time and 7 appears two times.

I understand if the x value or the y value appears zero times then the result is zero. But what do I do if the x and y values appear more than zero times but not the same number of times? Your post does not tell me what to do.

If the result should be zero when the x value and y value appear more than zero times, but not the same number of times then this may be your code.

In[6]:= Table[
If[
(xp = Map[Last, Position[a, x]]) == {} ||
(yp = Map[Last, Position[a, y]]) == {} ||
Length[xp] ≠ Length[yp],
0,
Plus @@ Map[Part[b, Sequence @@ #] &, Transpose[{xp, yp}]]
],
{x, 1, 150}, {y, 1, 150}]


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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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