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Matt Kindig

Northwestern University Chicago

355 total contributions since 2011

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How to classify shapes of this image as square, rectangle, triangle and circle?
Another approach is to calculate the best-fit bounding rectangle of each object, such that the bounding rectangle can be oriente...

7 years ago | 6

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Question

Determine which function was used to generate hggroup?
Hello everyone, Is there a way to determine which function (e.g., quiver(), scatter(), contour(), etc.) was used to generate ...

7 years ago | 1 answer | 0

1

How to average a column based on another column?
This is a good use of accumarray(): [ud,ix,iy]=unique( data(:,1)); output = [ud, accumarray(iy,data(:,2),[],@mean)...

7 years ago | 0

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How can I write a program to investigate whether a number belongs to matrix?
I think ismember() should do the trick: A=[1 2 3 5 21 2 4 0 11 3]; B = 11; C = ismember(B, A); %returns 1 B =...

7 years ago | 2

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Creating an array of datenum(s)
If I understand you correctly, this should do it: [~, time_index] = ismember( datenum(tv), second_tv);

7 years ago | 0

How to convert an image from rgb to lab by pixel by pixel matrix???
You can convert rgb to L*A*B colorspace using the makecform() and applycform() functions. From the documentation: cform...

7 years ago | 0

Is there a way to disconnect lines between data points while utilizing the plot function?
Another way is to insert a NaN between the dis-connected points, such as: x = [1;2;3;4;5;6;7;8;6]; y = [10;20;30;40;50;6...

7 years ago | 5

How to calculate the median for each day of the year in 91 years?
I think this is a good use of accumarray(). %some sample data, to illustrate approach Data = [1915 1 1 1000 1010; ...

7 years ago | 0

Finding minimum point from any function file input.
I would check out the documentation for fminsearch() and fminbnd(), or if you have the Optimization Toolbox, fminunc(): doc...

7 years ago | 0

How do I find values in a matrix which are closest to an integer which is the product of a given value?
I think I get what you are trying to do. I think the easiest way might be to use interpolation to fill in the missing values, as...

7 years ago | 1

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Read data from text file
You should be able to do it with textscan fid = fopen('/path/to/your/file.txt', 'rt'); output = textscan(fid, '%s %s %f ...

7 years ago | 3

and another "if" statement question
How long is the vector? Would this work? if all(A>3) %do something else %do other thing end

7 years ago | 1

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how to get some values from many text files and put them into the calculation ( please help)
One approach using regular expressions: %variables to average over AveVariables = {'Area', 'xbar', 'ybar', 'IXXw', 'IYY...

8 years ago | 0

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how to write program for following problem
I'm not going to given you the entire code, but to get you started, here's how you can do the parse: a = 'AD''BA''C'''; %...

8 years ago | 0

levenberg-marquardt in lsqcurvefit
Pass in an options structure: opts = optimset('Algorithm', 'levenberg-marquardt'); [parameters,resnorm,residual,exitflag...

8 years ago | 0

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Updating bounds in fmincon
You can implement the constraints on psi as a linear inequality constraint. If you check the documentation for your solver (e.g....

8 years ago | 1

How do I create variable names from string variables
If you can, avoid doing this. This explains why: <http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA...

8 years ago | 2

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Creating a matrix using a loop
[xx,yy]=ndgrid( -2:1:2, -2:1:2); xy = [xx(:), yy(:)]; x = xy(:,1); y = xy(:,2);

8 years ago | 1

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How to Multiply value in adjacent cell by cell above, Autofil formula in Matlab?
There is no generic "autofill" command. For the example you've given, the following logic would work: StartVar = 5; mult...

8 years ago | 1

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using multiselect uigetfile with dicomread
You probably need to pass in the full path to your DICOM file to dicomread(). Try this: for count = 1:numel(name) imag...

8 years ago | 1

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plotting normal vector in 3d
doc quiver3

8 years ago | 1

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Error using textread to read data containing "INF" or "NaN" with float data
Try using textscan() with the 'TreatAsEmpty' option: output = textscan([direct filename], '%22c %u %f %f %f %f %f %f %f %f ...

8 years ago | 2

How to read from a *.txt file to assign variables and paths
Easiest way is to parse with regular expressions and read into an output structure with named fields. %read in file str ...

8 years ago | 0

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Solving ODEs using matlab (ode45)
Did you forget the assignment sign? [T, XY] = ode45 ('diffxy', 0 10, [0 1 0])

8 years ago | 0

choose data points that nears each other and store in different matrix
One (non-loop) way: [x1,x2]=meshgrid(A(:,1)); [y1,y2]=meshgrid(A(:,2)); D = sqrt((x1-x2).^2+(y1-y2).^2); %distance m...

8 years ago | 0

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Solved

Read a column of numbers and interpolate missing data
Given an input cell array of strings s, pick out the second column and turn it into a row vector of data. Missing data will be i...

8 years ago

Solved

Fibonacci sequence
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: Inpu...

8 years ago

Solved

Relative ratio of "1" in binary number
Input(n) is positive integer number Output(r) is (number of "1" in binary input) / (number of bits). Example: * n=0; r=...

8 years ago

Solved

Vectorizing, too easy or too hard?
Please insert a . before any ^, * or / in the string. That's it!!

8 years ago

Solved

Specific Element Count
Given a vector _v_ and a element _e_, return the number of occurrences of _e_ in _v_. Note: NaNs are equal and there may be n...

8 years ago