MATLAB: Convert two array to a sparse matrix

Posted by CziX on Stack Overflow See other posts from Stack Overflow or by CziX
Published on 2010-04-27T20:31:53Z Indexed on 2010/04/27 20:33 UTC
Read the original article Hit count: 406

Filed under:

matlab

|

sparse-matrix

I'm looking for an a command or trick to convert two arrays to a sparse matrix. The two arrays contain x-values and y-values, which gives a coordinate in the cartesian coordinate system. I want to group the coordinates, which if the value is between some value on the x-axes and the y-axes.

% MATLAB
x_i = find(x > 0.1 & x < 0.9);
y_i = find(y > 0.4 & y < 0.8);

%Then I want to find indicies which are located in both x_i and y_i

Is there an easy way to this little trick?

© Stack Overflow or respective owner

Related posts about matlab

Importing matlab functions in matlab

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have some Matlab functions defined in .m files and I'd like to import them into Matlab (as in I'd like them to form part of the commands). Is this possible please and how can I do this? Thank you very much and regards, Krt_Malta >>> More
c# with matlab dll should be running on pc without matlab

as seen on Stack Overflow - Search for 'Stack Overflow'
hi, i have a very big problem. ich wrote a programm which is using a matlab dll. i build some classes with the matlab .net builder. it runs on my pc :) the problem is, i want to use ist on a pc without matlab. so i installed mcr, but it dont run :( what are the steps i should do? the system variable… >>> More
Matlab and .NET Interaction

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi All! I'm having an issue interacting between Matlab and .NET. I've managed to call .NET methods from Matlab code and vice versa. However, if I call a .NET method that, in turn, instantiates a Matlab object, it crashes (with a type initialization exception). Think about this scenario: a .NET… >>> More
Matlab matrix replacement assignment gives error

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, when i tried to update some part of a matrix, i got the following error message: ??? Assignment has fewer non-singleton rhs dimensions than non-singleton subscripts My code tries to update some values of a matrix that represent a binary image. My code is as follows: outImage(3:5,2:4,1) =… >>> More
MATLAB matrix replacement assignment gives error

as seen on Stack Overflow - Search for 'Stack Overflow'
I tried to update some part of a matrix, I got the following error message: ??? Assignment has fewer non-singleton rhs dimensions than non-singleton subscripts My code tries to update some values of a matrix that represent a binary image. My code is as follows: outImage(3:5,2:4,1) = max(imBinary(3:5… >>> More

Related posts about sparse-matrix

In R, when using named rows, can a sparse matrix column be added to another sparse matrix?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have two sparse matrices, m1 and m2: > m1 <- Matrix(data=0,nrow=2, ncol=1, sparse=TRUE, dimnames=list(c("b","d"),NULL)) > m2 <- Matrix(data=0,nrow=2, ncol=1, sparse=TRUE, dimnames=list(c("a","b"),NULL)) > m1["b",1]<- 4 > m2["a",1]<- 5 > m1 2 x 1 sparse Matrix of class… >>> More
Find the "largest" dense sub matrix in a large sparse matrix

as seen on Stack Overflow - Search for 'Stack Overflow'
Given a large sparse matrix (say 10k+ by 1M+) I need to find a subset, not necessarily continuous, of the rows and columns that form a dense matrix (all non-zero elements). I want this sub matrix to be as large as possible (not the largest sum, but the largest number of elements) within some aspect… >>> More
MATLAB: Convert two array to a sparse matrix

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm looking for an a command or trick to convert two arrays to a sparse matrix. The two arrays contain x-values and y-values, which gives a coordinate in the cartesian coordinate system. I want to group the coordinates, which if the value is between some value on the x-axes and the y-axes. % MATLAB x_i… >>> More
best way to get a vector from sparse matrix

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have a m x n matrix where each row consists of zeros and same values for each row. an example would be: M = -0.6 1.8 -2.3 0 0 0; 0 0 0 3.4 -3.8 -4.3; -0.6 0 0 3.4 0 0 In this example the first column consists of 0s and -0.6, second 0 and 1.8, third -2.3 and so on. In such case I would like… >>> More
Vectorizatoin of index operation for a scipy.sparse matrix

as seen on Stack Overflow - Search for 'Stack Overflow'
The following code runs too slowly even though everything seems to be vectorized. from numpy import * from scipy.sparse import * n = 100000; i = xrange(n); j = xrange(n); data = ones(n); A=csr_matrix((data,(i,j))); x = A[i,j] The problem seems to be that the indexing operation is implemented… >>> More