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Randomly picking a column index depending on the weight of its value (MATLAB)
Use randsample (Statistics Toolbox), which allows you to specify weights: col = randsample(1:size(A,2), 1, true, weight); and then your column is A(:,col). If you don't have the Statistics Toolbox: col = sum(rand<cumsum(weight));

Categories : Matlab

Printing simulink model to JPEG image
Check Create a Print Frame in the documentation, you need to use the frameedit function. There is a lot more stuff about printing in the documentation under Print and Export Models, I strongly suggest you have a read.

Categories : Matlab

Convert RGB to Grayscale while keeping maximum quality
The issue here is that your image has a depth of 24 bits but you convert it to an 8 bit grey-scale using the solution you linked. I presume ImageJ does the same thing by default. I think you can fix this by replacing 255 with (2^24)-1 in the line map = [(0:255)' (0:255)' (0:255)']/255; and uint8 to uint32 on the next line.

Categories : Matlab

find a value or the most similar value to an item in an array
You're close. To avoid the problem with the negative values, you can use abs to take the absolute value. You can then get the closest value using the second output of min: value=3; array=[1,2,5,6,9]; cur = abs(array-value); % df is the minimum distance, ind is the index of the minimum distance [df,ind] = min(cur); theneededvalue = array(ind);

Categories : Matlab

How to vectorize a piecewise periodic function in MATLAB?
You need to change your syntax slightly to be able to handle data of any size. I typically use logical filters to vectorise if-statements, as you're trying to do: function v = foo(t) v = zeros(size(t)); t = mod( t, 2 ) ; filt1 = t<0.1; filt2 = ~filt1 & t<0.2; filt3 = ~filt1 & ~filt2; v(filt1) = 0; v(filt2) = 10*t(filt2)-1; v(filt3) = 1; In this code, we've got three logical fil

Categories : Matlab

Calculate average from a series with fixed interval
The number of elements in your original series will always be a multiple of 12, so you can use reshape() to yield an 12 x n matrix. From there using mean() is straightforward to get the vector that you want. nSessions = 20; % Choose an integer to test number of sessions TestData = 1:12; % Dummy data - col 1 = 1, col 2 = 2...to check that our reshaping is correct data = repmat(TestData, 1, nSes

Categories : Matlab

How to remove a scalar structure in MATLAB?
I'm sure this was answered several times but it's just a common one liner in matlab: flat_final = [final{:}] To make the answer more complete you could use horzcat, vertcat and reshape to finetune your results. The technical term for your task is flatten so you might find many more snippets if you search for it.

Categories : Matlab

How can I produce a MATLAB bar graph of categorical responses?
Try this. First I created some sample data, for 10 students answering 5 questions: choices=['A' 'B' 'C' 'D'] %// I'll use this variable later as well for m=1:10 for n=1:5 answers{m,n}=choices(randi(4)); end end answers Then to find the frequency of each answer to each question, freq, I looked at each response individually, and counted up how many students gave that answer to tha

Categories : Matlab

How can a function have multiple return values in Julia (vs. MATLAB)?
How would I define my stat function in Julia? function stat(x) n = length(x) m = sum(x)/n s = sqrt(sum((x-m).^2/n)) return m, s end For more details, see the section entitled Multiple Return Values in the Julia documentation: In Julia, one returns a tuple of values to simulate returning multiple values. [...]

Categories : Matlab

converge values to range [-pi,pi] in matlab, NOT using wraptopi
To expand on @Ben Voight, you could use modulo-style operations this way: To wrap to [0, 2*pi], you'd do this: angle_rad = angle_rad - 2*pi*floor(angle_rad/(2*pi)); To wrap to [-pi, +pi], you'd add another term angle_rad = angle_rad - 2*pi*floor( (angle_rad+pi)/(2*pi) );

Categories : Matlab

Sort complex matrix and vector together in specific order
Answer is also very similar :) negIm = imag(e) < 0; [e1,ie1] = sort(e(~negIm)); [e2,ie2] = sort(e(negIm)); newe = cat(1,e1,e2); v1 = v(:,~negIm); v2 = v(:,negIm); newv = cat(2,v1(:,ie1),v2(:,ie2));

Categories : Matlab

How do I determine the coefficients for a linear regression line in MATLAB?
Judging from the link you provided, and my understanding of your problem, you want to calculate the line of best fit for a set of data points. You also want to do this from first principles. This will require some basic Calculus as well as some linear algebra for solving a 2 x 2 system of equations. If you recall from linear regression theory, we wish to find the best slope m and intercept b su

Categories : Matlab

Normalized cut: what does this code do?
I believe you came across a piece of code written by Prof Stella X Yu. Indeed, when W is positive this code has no effect and this is the usual case for NCuts. However, in a CVPR 2001 paper Yu and Shi extend NCuts to handle negative interactions as well as positive ones. In these circumstances dr (r for "repulsion") plays a significant role. Speaking of negative weights, I must say that personall

Categories : Matlab

How to convert uncompressed (*.LJPGEG.1) images of DDSM database into PNG format for all scanners
I have written a small utility to easily download, convert, view and get annotations from DDSM data, without the need for any manual work. The utility makes getting the DDSM database totally automatic, and is designed to help researchers. You just need to download the required cases and then follow the instructions on how to use my utility to convert the LJPEG files to LJPEG1 and then to other for

Categories : Matlab

Inversion and point subtraction on Elliptic Curve
I can help you in finding negative co-ordinate of y. I am explaining with a toy example: sum = [673 146] % Now to convert 2nd element of sum which is the y coordinate, do the following. sum(1,2) = -sum(1,2) % this will negate the 2nd element of 1st row of sum and store the result into sum. % now to perform subtraction, do the following. Assume that your addend is N1 = [ 6,5] and augend is the s

Categories : Matlab

Plot a figure in which there is an image that moves and rotates
Here is an example to start with, This is the simplified code in here. load topo n = size(topomap1,1); topo = (topo - min(topo(:))) ./ range(topo(:)); I = ind2rgb(round(topo*(n-1)+1), topomap1); [X,Y,Z] = sphere(n); for i = 1 : n [az,el,r] = cart2sph(X,Y,Z); az = az + 2 / n * pi; [X,Y,Z] = sph2cart(az,el,r); warp(X,Y,Z,I) axis equal off pause(.1) end You can change I

Categories : Matlab

Jacobi to Gauss-Seidel
The difference between a Jacobi solver and a Gauss-Seidel solver is that when you're solving for the solution of a variable x_i at the current iteration, you need to use the information from the previous variables (x_1, x_2, ..., x_{i-1}) as part of the solution for the current variable x_i. For Jacobi, you are simply using the previous iteration's solution to formulate the current solution. For

Categories : Matlab

Efficient way of using ssim() function in Matlab for comparing image structures (or any other alternative)
Never mind, here I'm going through all image pairs, twice (switched parameters), which is not needed.So it is possible to reduce the speed by n-1/2. If you want efficiency over accuracy (which in my case, it is), finding the score from the correlation of histograms is one possible way. It took me 55 seconds to process 72 frames with ssim(), while only 1.2 seconds with difference of histograms.

Categories : Matlab

Sum of element in Vector to get the correspond Matrix
You could think about the problem in a different way - essentially what you're calculating is the average of the distance between the start points of each facility and the end points of each facility. i.e. <------start dist------> [ A ][ B ][ C ][ D ] <--------------end dist--------------> You can calculate the start a

Categories : Matlab

How to implement a derivative of a symbolic function by a 'symfun' in Matlab?
In newer versions of Matlab (I'm using R2014b) the error message is clearer: Error using sym/diff (line 26) All arguments, except for the first one, must not be symbolic functions. So, it looks like sym/diff cannot take a derivative with respect to what the documentation calls an abstract or arbitrary symfun, i.e., one without a definition. This limitation is not explicitly mentioned in th

Categories : Matlab

How to find the decision boundary for two set of data for knn classifier
For simply visualizing the decision boundary and decision regions, it is often satisfactory to brute-force test your whole domain of interest. Specifically, you'd define a set of discrete points that span your domain of interest, you'd step through each point evaluating to which class the point belongs, then you'd plot the results. Maybe something like this: %define your domain of interest dx

Categories : Matlab

Spatial cross correlation field of matrix
Simply search for values in pval that are less than 0.001, then use this to index into corelMat and set those values to zero. As such: corelMat(pval < 0.001) = 0; pval < 0.001 generates a logical matrix where true denotes those p-values that are less than 0.001 and false otherwise. By providing a logical matrix that is the same size as corelMat as an argument into corelMat, you are only

Categories : Matlab

Substitute value to Matrices by given a Row Vector and Their Corresponding Location Matrix
Pretty easy. Simply use A to index into B: A = [2 4 1 5 3; 5 2 3 4 1; 1 2 3 4 5]; B = [0.05 0.03 0.06 0.04 0.02]; B(A) ans = 0.0300 0.0400 0.0500 0.0200 0.0600 0.0200 0.0300 0.0600 0.0400 0.0500 0.0500 0.0300 0.0600 0.0400 0.0200 You're probably thinking... woah!... how the heck does this work? Because of how A is structured, eac

Categories : Matlab

image filtering separable matrix speed MATLAB
It seems like an optimization error. I'd use the function conv2 instead. Let's write a sample code: mOutputImage = conv2((vFilterCoeff.' * vFilterCoeff), mInputImage); mOutputImageSep = conv2(vFilterCoeff, vFilterCoeff.', mInputImage); Try those in a loop where the length of vFilterCoeff (Row Vector!!!) is getting bigger. update us what are the result now.

Categories : Matlab

How to assign key to push button on Matlab?
The KeyPressFcn that is called is going to be the one that belongs to the object in focus when the key is pressed. This is probably going to be the last object that was clicked on. Here you set the KeyPressFcn as a property of the pushbutton but this will only be called when the pushbutton is the object in focus. This includes the figure window as well. This example shows how to implement a ke

Categories : Matlab

Getting FFT peaks from data
You can use findpeaks function from octave signal package: http://octave.sourceforge.net/signal/function/findpeaks.html

Categories : Matlab

converting an object to line
You are looking for the morphological skeleton of the image. You can find that with the function bwmorphby: bwmorph(BW,'skel',Inf); See Docs

Categories : Matlab

Plot lines where my data is constant
Something like this works for you? The 2:2:10 sets the level wanted to show. If you want to see better the 10 valued level youcan play a bit with the axis function subplot(121) contour(data,2:2:10,'ShowText','on') subplot(122) contourf(data,2:2:10,'ShowText','on') If you want the plot upside down you can do contour(flipud(data))

Categories : Matlab

Recursive function is only generating half the desired outputs
Solved it function inputArray = inputBuilder(currBuild, allInputs, currIdx) inputArray = []; if currIdx <= length(allInputs) for i = 1:length(allInputs{currIdx}) mybuild = [currBuild allInputs{currIdx}(i)]; inputArray = [inputArray inputBuilder(mybuild,allInputs,currIdx + 1)]; end else if isempty(inputArray) inputArray = {currBuild}; else inp

Categories : Matlab

Variable error rate of SVM Classifier using K-Fold Cross Vaidation Matlab
You can check wiki, In k-fold cross-validation, the original sample is randomly partitioned into k equal size subsamples. and The k results from the folds can then be averaged (or otherwise combined) to produce a single estimation. So no worries about different error rates of randomly selecting folds. Of course the results will be different. However if your error rate is in wide ran

Categories : Matlab

on the use and understanding of pwelch in matlab
Your results are fine. dB can be confusing. A linear plot will get a good view, Fs = 1000; % Sampling frequency T = 1/Fs; % Sample time L = 1000; % Length of signal t = (0:L-1)*T; % Time vector y = sin(2 * pi * 50 * t); % 50Hz signal An fft approach, NFFT = 2^nextpow2(L); % Next power of 2 from length of y Y = fft(y

Categories : Matlab

Matrix dimensions must agree error in Matlab?
You are trying to multiply exp(-a*5) with sin(2*pi*f*t), element-by-element. That's only possible if the two vectors have the same size. In your code, t is 1x320001, while a is 1x101. I guess what you want is: sr = 16000; T = 2; % seconds duration t = 0:(1/sr):T; n = 1; f = ((2^(1/12))^(n-49))*440; a = linspace(0,1,numel(t)); y = exp(-a*5).*sin(2*pi*f*t); plot(t, y); Note that I changed the

Categories : Matlab

svd of a VERY LARGE sparse matrix
The approximate matrix decomposition into a product of three matrices is called CUR. However I'm not sure the matlab contains its implementation.

Categories : Matlab

MATLAB : Alphanumeric character string extraction
Ok I'm not entirely sure about whether you need letters all the time, but here regular expressions would likely perform what you want. Here is a simple example to help you get started; in this case I use regexp to locate the numbers in your entries. clear %// Create dummy entries Case1 = 'NI000166'; Case2 = '12ABC345'; %// Put them in a cell array, like what you have. CasesCell = {Case1;Case2

Categories : Matlab

How to simply downsample a triangular mesh?
You should downsample your data, [x,y]=meshgrid(1:15,1:15); tri = delaunay(x,y); z = peaks(15); trisurf(tri,x,y,z) figure x1 = x(1 : 2 : end,1 : 2 : end); y1 = y(1 : 2 : end,1 : 2 : end); z1 = z(1 : 2 : end,1 : 2 : end); tri1 = delaunay(x1,y1); trisurf(tri1,x1,y1,z1) You could even use downsample function on each data.

Categories : Matlab

Convert binary image to a Gussian points
You could try a hard cap. Either save the locations of the white points before the convolution or find the location of all points > 1 and set them to 1 like this: B(B>1) = 1

Categories : Matlab

How to plot different data in parallel (in continuation of the previous one)
You can still use hold on and plot each day separately (if I understand your question properly, this is what you want, separate plotting). Simply make sure your x-axis values are correct. So e.g. if you have one measurement value per hour, the plot day 1: plot(1:24,valDay1,'k-') then for day 2: plot(25:48,valDay2,'r-') etc. This will line things up correctly. Also, consider using a datetime

Categories : Matlab

In matlab, increment different column element for every row in without using a loop
You can do this by using the linear index to each of the elements you want to address. Compute this using sub2ind: >> A = zeros(4) A = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 >> B = [4 2 3 1] B = 4 2 3 1 >> i=sub2ind(size(A),B,1:4) i = 4 6 11 13 >> A(i) = A(i)+1 A =

Categories : Matlab

MATLAB CLASSES getter and setters
Implementation Since your class is currently a subclass of the default Value class, your setters need to return the modified object: function obj = set.name(obj,name) end function obj = set.age(obj,age) end From the documention: "If you pass [a value class] to a function, the function must return the modified object." And in particular: "In value classes, methods ... that modify the object mu

Categories : Matlab


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converting an object to line
Plot lines where my data is constant
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