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# Guillaume

### University of Brighton

7,188 total contributions since 2012

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Select specific number of random ones placed in a zeros matrix
m = zeros(1024, 1024); m(randperm(numel(m), 20)) = 1; %place 20 ones randomly in m.

3 hours ago | 0

split = textscan(tline, '%s%f%f%f'); txt = split{1} numbers = cell2mat(split(2:end))

3 hours ago | 0

How do I track the number of instances of a given handle?
I'm curious what you mean by "inheriting that class appears to put a lot of constraints on what I can do with my existing code i...

3 hours ago | 0

How to get field value from a struct as a variable in order to use in a code?
There's no need to. Creating separate variables is usually not a good idea. Wherever you were going to use X, use yourstruct.X. ...

4 hours ago | 2

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Having trouble finding the mean of array elements between two indices
See my comments to the question. Using a matrix, and assuming you're using R2019b since you haven't indicated a matlab version:...

5 hours ago | 0

Add empty cell inside a cell array considering a single array
Surely, by now, with all the questions you've asked, you should be able to manipulate cell arrays yourself. Anyway: desiredlen...

5 hours ago | 0

Is it possible to use a variable name like this within Matlab?
Confusingly, variable names can mean two different things now in matlab. A generic variable name, e.g. >> A = 5 is limited to ...

11 hours ago | 2

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Why the threshold is 0.90 used to obtain the white component from RGB channels ?
You will have to ask whoever wrote that code why they chose that threshold. Most likely, the answer will be : because it worked...

12 hours ago | 0

How to index something based on numbering order???
Here is one way: %input x = [2; 3; 7; 5; 1] %generate random matrix without worrying about the order A = rand(size(x, 1),...

12 hours ago | 0

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How to assign specific colors to every quiver?
I can't remember if quiver did have children before R2014b (when the graphics system changed drastically) but since R2014b it do...

17 hours ago | 0

Why is my regular expression always greedy?
Matlab regex engine has the odd peculiarity that . also matches \n by default, whereas other engines don't. So your greedy .* in...

1 day ago | 0

Using data from a cell
I need new variables created for each of the character vectors No! As Stephen already told you this would worst way to go about...

1 day ago | 0

How to create a new table array combining the values every n,th element from two different table arrays
In my case I would like to add every 60 values of A to add 59 consecutive values of B So, assuming that A and B are indeed vect...

1 day ago | 0

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mod gives incorrect result
See my comment to Kalyan's answer for why your naive attempt doesn't work, and learn about floating point numbers so that you ca...

2 days ago | 2

How do I get my matrix dimensions correct?
t_loading, v_trailertank, and co. (the random variables) are column vectors 1000 rows by 1 columns. To these you are adding x./...

2 days ago | 0

Use rowfun to sum multiple columns by group
rowfun is not the correct function for this. rowfun applies the function by rows and consider the input variables as separate in...

3 days ago | 0

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"Index exceeds the number of array elements (11)."
You create a variable called disp: disp = 'RLC Circuit' %removed brackets which didn't anything Which shadows the built-in ...

3 days ago | 0

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What is the default varargin in the GUI callbacks? What are the differences between varargin{1} and varargin{2}.Source?
Yes, as Stephen says in his very thorough comment, that advice is utter rubbish. Don't do that it pointlessly obfuscate the code...

6 days ago | 0

I have a Table in MATLAB. In one colum, lots of texts are seperated in comma. I wish to delimate those in seperate colums.
It's not clear what you want as an output since for each row you're going to get a different number of elements after the split....

6 days ago | 0

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For this you should contact Mathworks directly. We're just a bunch of volunteers here.

9 days ago | 0

Create an array iterating on another array
If I understood correctly: out = zeros(size(N)); for row = 1:size(N, 1) [isfound, where] = ismember(SP, G{row}(1, :)); %...

9 days ago | 0

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Create new .wav files around findpeak outputs
Here's how I'd do it: infile = 'C:\somewhere\somefolder\test_100m.wav'; %I'd recommend you use full path instead of relying on...

9 days ago | 1

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calculating the number of days within each month for a range of dates
You've got to learn to work with datetime arrays. There's no need to use datenum to construct datetimes, and adjusting the defau...

10 days ago | 0

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Transformation of the Matrix in a Loop
With your invented notation it's difficult to know what you actually have in matlab. Assuming you have a matrix such as: Z = [...

11 days ago | 1

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Old Matlab script not running on newer version
The equivalent of your wavwrite using audiowrite is: audiowrite(fullfile(subj_name, sprintf('%d.wav', block_num)), recordedaudi...

13 days ago | 1

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Merging matrices by comparison of values of several columns
Nearly right [~, whichArows, whichBrows] = intersect(out1(:, 2:4), out2(:, 2:4), 'rows'); C = [out2(whichBrows, 5), out1(which...

14 days ago | 0

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Using For Loop to get different outcomes
if ismember(psi_value, [0.05, 0.15, 0.25, 0.35]) %maybe use ismembertol s_plot = 0.8; else s_plot = 0.2; end Note ...

14 days ago | 0

Store a group of points (given x, y, and value) into image efficiently
img = zeros(1000, 1000); img(M(:, 2) + 1000 * (M(:, 1) - 1)) = M(:, 3);

14 days ago | 1

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Negative Value when using Trapz
Can someone tell me as to why this is the case Because your x vector is decreasing, so is negative for each trapeze a = trapz...

15 days ago | 0

Create two arrays on the basis of other arrays
%first find which of A or B elements are going into. Only depends on V isA = false(size(V)); %put in A (true) or B (false) lA...

15 days ago | 0

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