Info

此问题已关闭。 请重新打开它进行编辑或回答。

Link the 2th column of a matrix to the first depending on another matrix.

1 次查看（过去 30 天）
Klaas
Klaas 2015-2-9
关闭： MATLAB Answer Bot 2021-8-20
Hello,
I'll just give a simple example to show what I want:
I have a matrix
A=[1,4;
2,5;
3,6];
And a long vector B with values 1,2 and 3 in an undefined order.
B = [1;3;1;2;1;3...];
From A and B I want to make one matrix C in which the first column is vector B and for the second column I want to let the values depend of the value of B. So if the value of B is 1 I want to get a 4, if 2 I want 5, if 3 I want to get 6. So each time the according value defined in matrix A.
Thanks in advance!

此问题已关闭。

回答（2 个）

Image Analyst
Image Analyst 2015-2-9
How about this:
A=[1,4;
2,5;
3,6];
B = [1;3;1;2;1;3];
C = [B, A(B,2)]
C =
1 4
3 6
1 4
2 5
1 4
3 6
  3 个评论
显示 1更早的评论
Klaas
Klaas 2015-2-10
编辑：Klaas 2015-2-10
I still have a problem. This works for my example but in my script the numbers 1,2 and 3 from the example are decimal fraction. So I always get the 'Subscript indices must either be real positive integers or logicals.' error.
Someone who has a different solution?
Image Analyst
Image Analyst 2015-2-10
Let's say the number is 2.37. So you want row #2.37 from A. Can you explain exactly what it means to you to get the 2.37'th row from the second column of A?
Roger Stafford
Roger Stafford 2015-2-10
Perhaps what you need is
[~,ix] = ismember(B,A(:,1));
C = A(ix,:);
This assumes that every value in B is to be found somewhere in the first column of A. If not, you will receive an error message.
  1 个评论
Image Analyst
Image Analyst 2015-2-10
Oh, is that what he meant? I thought the B was the row numbers of A that he wanted to extract. I guess it's ambiguous but you might be right. Of course having the first column of A be row numbers didn't help clarify it, in fact it made it more ambiguous.

此问题已关闭。

标签

尚未输入任何标签。

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by