Help splitting a matrix based on a specified column.
显示 更早的评论
I have matrix(A) with 13x3 like this:
No. value1 value2
1 12 0
2 4 0
3 8 0
4 1 0
5 9 0
6 5 0
7 3 0
8 1 0
9 1 2
10 12 0
11 11 12
12 10 0
13 3 4
And I want to split it to two matrix B and C like this:
B=
No. value1 value2
1 12 0
2 4 0
3 8 0
4 1 0
5 9 0
6 5 0
7 3 0
8 1 0
10 12 0
12 10 0
which is only colum of value2=0
And matrix C=
No. value1 value2
9 1 2
11 11 12
13 3 4
which is only colum of values2 not zeros
I did :
nonzeros(A)
but it gave me a one colum matrix which is not I want. I need to keep up the relation between value1 and value2.
find(shearingedges(:,1)>0) & (shearingedges(:,2)>0):
But it gave me a colum matrix with 1 and 0.
Could anyone help please?
1 个评论
Walter Roberson
2011-1-22
Unfortunately the formatting of this question makes it difficult to figure out what you are asking. It would help to edit the question so that the different rows of the examples were on different lines.
采纳的回答
Paulo Silva
2011-1-22
A=[1 12 0 2 4 0 3 8 0 4 1 0 5 9 0 6 5 0 7 3 0 8 1 0 9 1 2 10 12 0 11 11 12 12 10 0 13 3 4]
B=A(find(A==0))
C=A(find(A))
3 个评论
Sean de Wolski
2011-1-25
No need for the call to find()
Todd Flanagan
2011-1-25
Worravit says, "Thank you so much paulo and Rob
your answers very helpfull."
Paulo Silva
2011-1-26
Sean I know that find wasn't required, I use find often just for the code to be more readable by new users.
更多回答（2 个）
Rob Graessle
2011-1-22
Try this:
B=A(A(:,3) == 0, :)
C=A(A(:,3) ~= 0, :)
Hy
2011-1-25
There seem to be 3 questions here.
1. How to select rows from a matrix according to a criterion?
2. How to select rows from a matrix according to two criteria?
Answers:
myCriteria = A(:,3) == 0;
B = A(myCriteria,:);
C = A(not(myCriteria));
2. The answer-seeker then poses the code
find(shearingedges(:,1)>0) & (shearingedges(:,2)>0):
if we remove the find(), a parenthesis, and end the line with a semicolon, we get
myCriteria = shearingedges(:,1)>0) & shearingedges(:,2)>0;
This is valid syntax for logical indexing, and the rest of the syntax from question 1 can be used. The "column matrix with 1 and 0" is the vector used for logical indexing. MATLAB treats a 1 as equivalent to true and a 0 as equivalent to false, and so uses them when displaying logical arrays.
3. The link above gives a full explanation, but simply, nonzeros is not directly helpful for indexing because it returns only the values of an array that are nonzero.
类别
在 帮助中心 和 File Exchange 中查找有关 Matrix Indexing 的更多信息
产品
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
