MATLAB – extracting rows of a matrix
Like this: a([1,3],:) The comma separates the dimensions, : means “entire range”, and square brackets make a list.
matlab
Align already captured rgb and depth images
prologue This answer is based on mine previous answer: Does Kinect Infrared View Have an offset with the Kinect Depth View I manually crop your input image so I separate colors and depth images (as my program need them separated. This could cause minor offset change by few pixels. Also as I do not have … Read more
Neural network in MATLAB
I wrote a simple example of an XOR network. I used newpr, which defaults to tansig transfer function for both hidden and output layers. input = [0 0 1 1; 0 1 0 1]; %# each column is an input vector ouputActual = [0 1 1 0]; net = newpr(input, ouputActual, 2); %# 1 hidden … Read more
How to plot inequalities
Try this: The red area is where both inequalities are satisfied. [X,Y]=meshgrid(0:0.01:1,0:0.01:1); % Make a grid of points between 0 and 1 p1=0.1; p2=0.2; % Choose some parameters ineq1 = Y<p2*(1-p1); ineq2 = X<p1*(1-(Y./(1-p1))); colors = zeros(size(X))+ineq1+ineq2; scatter(X(:),Y(:),3,colors(:),’filled’)
Declaring a global variable in MATLAB
You need to declare x as a global variable in every scope (i.e. function/workspace) that you want it to be shared across. So, you need to write test1 as: function test1() global x; x = 5; end
Suppress exponential formatting in figure ticks
EDIT According to this technical solution page, the recommended way of formatting the tick labels is this (you can use any of the number formatting functions like NUM2STR, SPRINTF, MAT2STR, or any other..) y = cool(7); bar(y(:,1)*1e6) set(gca, ‘YTickMode’,’manual’) set(gca, ‘YTickLabel’,num2str(get(gca,’YTick’)’)) However there seems to be a bug when it comes to the Z-axis (the … Read more
What does operator “dot” (.) mean?
The dot itself is not an operator, .^ is. The .^ is a pointwise¹ (i.e. element-wise) power, as .* is the pointwise product. .^ Array power. A.^B is the matrix with elements A(i,j) to the B(i,j) power. The sizes of A and B must be the same or be compatible. C.f. “Array vs. Matrix Operations”: … Read more
How does subplot work and what is the difference between subplot(121) and subplot(1,2,1) in MATLAB?
Long story short, there is no difference. How subplot works is the following: subplot(m,n,p); %//or subplot(mnp); You have three numbers that are used within subplot. subplot places multiple figures within the same window. You can place plots within a m x n grid, where m contains the number of rows and n contains the number … Read more
resizing 3D matrix (image) in MATLAB
You could use interp3 (since you want to interpolate 3D data): im=rand(2,3,4); %% input image ny=3;nx=3;nz=5; %% desired output dimensions [y x z]=… ndgrid(linspace(1,size(im,1),ny),… linspace(1,size(im,2),nx),… linspace(1,size(im,3),nz)); imOut=interp3(im,x,y,z);
Multiply a 3D matrix with a 2D matrix
As a personal preference, I like my code to be as succinct and readable as possible. Here’s what I would have done, though it doesn’t meet your ‘no-loops’ requirement: for m = 1:C Z(:,:,m) = X(:,:,m)*Y; end This results in an A x D x C matrix Z. And of course, you can always pre-allocate … Read more