Use a symfun as index of a matrix matlab answers matlab. Oct 07, 2009 the min and max functions in matlab return the index of the minimum and maximum values, respectively, as an optional second output argument. Matrix indexing of a 3d matrix, one by one each 3d. The min and max functions in matlab return the index of the minimum and maximum values, respectively, as an optional second output argument.
Creating a matrix is as easy as making a vector, using semicolons. Jul 17, 2018 i have a 3d matrix 40x181x361, i want to find the index for the maximum value for each of the 40. My question is that if there is a way to extract or find out one specific column vector from the 3d matrix if i have the index number between 1 and 100. As most of us will agree, an easy to use environment is a must for integrating tasks of computing, visualizing and finally programming. How do i find the indices of the maximum or minimum. These masks are for 10 respective slices, so i want to combine them and make a 3d array 256x256x10. Efficiently converting a 3d matrix to a 2d matrix matlab. Extracting a column vector from a 3d matrix matlab answers.
Indexing a 3d matrix with a 2d matrix matlab answers. I have a 3d array of temperature data that looks like this. A multidimensional array in matlab is an array with more than two dimensions. The color of the line between each two points is related to the index of the end point. A matlab user recently posed this question in the comp. I would like to change the linear index to a 2d array index d x e called a to group the data in a more meaningful way, thereby creating a 4d array. Generally, though, i think youve correctly identified the issue as my mixing cells and normal matrices, and i should probably just stop trying to use cells and work out how to stick a 3d matrix in a table. Create a 3by4by2 array and permute it so that the first and third dimensions are switched, resulting in a 2by4by3 array. These matrices have several slices of zero only matrices, which i need to remove.
So that makes a dictionary a 3d matrix a set of the 2d matrix. Get max value and index of multidimensional array matlab. Essentially you are specifying a rectangular block in the 3d matrix a chunk out of the larger full 3d block. Ill assume you want to remove the first and last 100 leaving the middle 200. For example, first define a 3by3 matrix as the first page in a 3d array. Learn more about image analysis, image processing, mask. Matlab allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages. So i want to store these matrices in a 3d matrix with third dimension as index of each 7x7 matrix which makes a 3d matrix of size 7x7x72. What the algorithm is doing is to build the indexes of the matrix.
Now assume you have one bookshelf of 5 rows full with different dictionaries. I can create a video in matlab by putting the imshow or imagesc command in a for loop but i want to extract something equivalent from matlab to put in youtube or imbed in a. This matlab function fills threedimensional polygons. Regular newsgroup contributor peter acklam posted this solution that uses sub2ind and linear. These pixels are given as a 2d array determined from a threshold in greyscale.
It was originally designed for solving linear algebra type problems using matrices. Learn more about matlab, code, indexing, index, for loop, loops, loop, 3d matlab. Mathworks is the leading developer of mathematical computing software for. Representing data as a surface functions for plotting data grids. Hi, id like to set several pixels in a base image to a color. I need to generate a 2d sparse matrix of n3xn3, the elements of 3d matrix elements to get stored in the diagonal and off diagonal elements of 3d matrix. Note that in matlab the first index of a vector or matrix starts at 1, not 0 as is common with other programming languages. The matrix dimensions indicate frame height, width and frame number. I want the 3rd dimension to be concatenated along dimension 1 in the 2d matrix. Each element is defined by two subscripts, the row index and the column index.
In other word, i want to get a 371 matrix matrix b from matrix a, using index vector v to get the value corresponding to the column of index specifying by vector v. This content is being served through the afs servers hera. Follow 97 views last 30 days erfaneh on 6 sep 2014. Matlab is a highlevel language and interactive environment that enables you to perform computationally intensive tasks faster than with traditional programming languages such. What if i want to create a matrix of dimension 4x4x3. In the code below, the variable desired illustrates what i want to achieve, but i want to do it more efficiently than via a for a loop.
It will go through every possible permutation of x, y, and z and then will expect to set it to a single value. Adding values to 3d matrix matlab answers matlab central. There are ways to create random 2d matrices using randint function. Matlab matrix laboratory is a multiparadigm numerical computing environment and proprietary programming language developed by mathworks. Learn more about symfun, matrix manipulation, index. Aug 20, 2016 i have a logical mask of locations i want to image. What i cant figure out is how to take this information and pull out the 3 dimensional vector for each of these pixels from my larger 3d matrix. Remove slices of 3d matrix matlab answers matlab central. Oct 24, 2018 the index refers to which column in 3d matrix i want to get the value for each 1st and 3rd dimension. The inputs for the planoconvex lens function are the height of the ray, refractive index, thickness of lens, radius of spherical surface, and resolution for computations in the zaxis. I want matlab to only consider the row and coloumn when taking the mean not the third dimension take the mean of i and j. How can i concatenate a 2d matrix to a 3d cell array. Finding indices of array elements in 3d matrix matlab answers.
What i have are three 1d vector lenght10, say x1,1,2,3,4 y55. The code is generated is using for loop and if condition, but the eigen value calculation becomes difficult if n becomes large. Hello, i need the sizes of two 3d matrices to match. Learn more about 3d, matrix, matrices, indexing, index matlab. How do you catalogueindex a matrix to be concatenated into a 3d matrix. Is there anyone having an idea how to solve it prefer not using loop.
Preferably, this would be done within a for loop, however i dont understand how to catalogue or is the term index. Matlab 3d matrix same index condition matlab answers. Now, we need to find the indices of all the column values of v in m row wise that appear all together. If you want to define a 3d matrix containing all zeros, you write. Indexing a 3d matrix with another 3d matrix matlab answers. Op did note, however, it will take too long to run in the actual data so i presume the real case is quite a lot larger. So what i would like to do is pull all 3 columns of my data and create a new matrix that only has the data items where the logical vector is true row 1, row 10, row. Mar 18, 2014 i have a 3d matrix a with dimension of 10,10,320. I would like to convert a 3d matrix into a 2d matrix.
Indexing is a key to the effectiveness of matlab at capturing matrix oriented ideas in understandable computer programs. If you have any questions about this content, please contact the administrators of this directory, who made it publicly available. Certain commercial products are cited within these web pages in order to document the matrix market and its repository contents. Sep, 2018 i want to stitch together a series of images 2d matrices into a 3d image 3d matrix.
Matlab has several indexing styles that are not only powerful and flexible, but also readable and expressive. Extracting a column vector from a 3d matrix matlab. I have a 3d matrix 40x181x361, i want to find the index for the maximum value for each of the 40. With your answer you then used this index on the third column only c and then applied that to exampledata. Indexing a 3d matrix with another 3d matrix matlab. Feb 03, 2011 using find in a 3d matrix in matlab learn more about 3d, matrix, array, find, 3d matrix, 3d array, 2d.
I tried using the limit, and the modified function works perfectly from the range 200 300 including index for floating point in the column matrix. Taking the mean of a 3d matrix matlab answers matlab central. How do i find the indices of the maximum or minimum value. The matrix market is a service of the mathematical and computational sciences division of the information technology laboratory of the national institute of standards and technology. Matlab matlab is a software package for doing numerical computation. Indexing 3d matrix with three 1d vector matlab answers. That matrix has all the information necessary to perform different analyses. Is there anyone having an idea how to work with this, not using for loop the dimension is very huge. Indexing a 3d array with a vector matlab answers matlab.
How to create a 3d matrix using the 2d matrices matlab. If i label the column vectors320,1 with 1 100, i will get 100 column vectors with dimension of 320,1. Get exact indices of max value in 3d matrix matlab. I know this question was originally asked several years ago, but i know others have this same belief.
Heres how you can find the position of 8 in your 3d matrix. I am using bwconncomp to get the indices of the pixels in each of these objects. Multidimensional arrays are an extension of 2d matrices and use additional subscripts for indexing. Given a large number of 3d coordinates xyz with all intensities are the same, say 1 or 255. If x, y, and z are matrices of the same size, fill3 forms a vertex from the corresponding elements of x, y, and z all from the same matrix location, and creates one polygon from the data in each column if x, y, or z is a matrix, fill3 replicates any column vector argument to produce matrices of the required size. How to index a matrix in matlab matlab answers matlab. Cropping a 3d matrix matlab answers matlab central. Creating a 3d array out of multiple 2d arrays matlab. Matlab has since been expanded and now has builtin functions for. Surface plots are useful for visualizing matrices that are too large to display in numerical form and for graphing functions of two variables. In a matrix, the two dimensions are represented by rows and columns. It means that in output matrix a, we should have three set numbers 1,2,3. Get exact indices of max value in 3d matrix matlab answers. My question is that if there is a way to extract or find out one specific column vector from the 3d.
Apr 30, 20 yes, you are correct, the actual data is similar to 1498. I want to draw a 3d xyz plot as shown in the fig attached,each two neighbour points are connected with an arrow line. Mathworks is the leading developer of mathematical computing software. Feb, 2012 creating a 3d array out of multiple 2d arrays. If i want to shift the rows of an mbyn matrix a by k places, i use a. Mar 14, 2018 get exact indices of max value in 3d matrix. If the matrices or vectors which are special cases of a matrices are of the same dimensions then matrix addition, matrix subtraction and. One area in which matlab excels is matrix computation. Oct 24, 2018 in other word, i want to get a 371 matrix matrix b from matrix a, using index vector v to get the value corresponding to the column of index specifying by vector v. All ones uses ones, all nans uses nan, all false uses false instead of zeros if you have an existing 2d matrix, you can assign an element in the 3rd dimension and the matrix is augmented to contain the new element.
Ive done this separately but the final 3d matrices mismatch, so i have written a code that will count how many slices are cut at the beginning and at the end for each dimension xmin, xmax, ymin, ymax, zmin, zmax of the first. The element values are what is being used to form images with commands such as imagesc or imshow. Logical indexing into 2d matrix matlab answers matlab. Find index in 3d matrix for maximum value matlab answers.
Run the command by entering it in the matlab command window. I have a 3dimensional matrix c of size m, n, k, and i have an index array id of size m,n that indexes into the last dimension. Permute array dimensions matlab permute mathworks france. As noted in my original answer, if preallocate, id agree. Z rand3,4,8 it contains 8 slices of data on a 3x4 grid. And i dont know how to concatenate the cataloguedindexed images within the for loop. Learn more about image stack, image import, digital image processing matlab. I would like to have a plot wich shows the index in 3 dimentions and the value e. How do you catalogueindex a matrix to be concatenated into a. Matlab is the language of technical computing at leading engineering and science companies and the standard software at more than 5000 universities worldwide. Matlab sort 2d and 3d matrix and access through index. Learn more about matrix manipulation, matrix array, matrices, matrix, cell arrays, image processing.
1477 1158 1031 1239 1490 1182 301 302 1489 930 91 447 317 1193 54 451 788 1512 884 387 398 1218 716 1393 1413 821 1308 1454 533 528 265 203 561 1143 1246 1416 850 867 1238