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Joseph Cheng


Last seen: 1 día ago
662 total contributions since 2014

Systems Engineer for Electro-Optical Systems

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Answered
How to find the two minimum values ?
well to remedy this you shouldn't "delete" the entry of the min point but stick in a large value or Nan and use nanmin(). by de...

alrededor de 21 horas ago | 0

Answered
3d to 2d matrix
take a look at the function squeeze() for ind = 1:3 val(1,1,ind)=-ind; end disp(val) u2 = squeeze(val); disp(u2)

alrededor de 23 horas ago | 1

| accepted

Answered
How to get data points within current camera view?
So... if i'm not mistaken pan in matlab moves the axes limits of the plot and not panning/translating the camera, similarly zoom...

alrededor de 23 horas ago | 0

Solved


Find the Pattern 1

2 días ago

Answered
Looking for a way faster than find?
without doing some testing to actually test if its faster you can use the found 1's in a to only select a list of indexes A = ...

2 días ago | 0

Answered
Incorrect datatip location on interpolated data
so you can see what is happening if you plot it as just markers in this animated example: figure; hold on; hPlot = plot(1:10, ...

2 días ago | 0

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Answered
Taking average of pixel values across multiple frames
couldn't you just put it into a non cell matrix of 5504 x8256 x 3 then use mean(data,3) to take the mean in the 3rd dimension? o...

6 días ago | 1

Answered
Why am I getting an invalid file identifier error when using "parfor" but the same function works fine (albeit slow) with "for"?
From the looks of it you've opened a file then trying to use parfor to grab items out of the opened file. However thats where t...

6 días ago | 0

Answered
How to get rid of blank space in a heatmap panel of 3 figures?
have you looked at the functions axis equal or axis square those might be applicable to you and not have to only use top h...

6 días ago | 0

Answered
How read in comment style to skip the header of a text file?
you can quickly scan the file(s) for the number of header lines like file= 'Graphite_Node_test.txt'; fid = fopen('Graphite_Nod...

6 días ago | 0

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Answered
Contour is plotting my data in reflected order?
From a quick test you might not be asigning the x and y values when performing your contour() function. by doing so matlab will...

6 días ago | 0

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Answered
Create a matrix with elements clockwise
While probably not the most efficient way you can fill in edges like i've done here: clc;clear all x = zeros(5,8); %generate m...

7 días ago | 1

Answered
Update a for loop with if statements
Without running your code i think you can create a sign variable of (-1)^(0 or 1) which switches between 0 or 1 depending on whe...

9 días ago | 0

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Answered
Represent array in percentage
you would take your array, subtract the minimum, then divide by the resulting maximum x 100 x = [2.4:.4:4.2]; x = x-min(x); ...

9 días ago | 1

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Answered
How to make the length/dimension of 6 different 3D vectors the same?
probably the easiest way is to fill a zero array created to be the same max size then populate the indexes with the values: var...

12 días ago | 1

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Answered
Extract pixel values inside a Binary Mask
since you already created a binary mask you can just index multiply " .* " the mask with the original image as outside is 0 and...

12 días ago | 0

Answered
how to color and label only certain histogram bars?
Here is an example for @Adam Danz said with using bar y = randn(100); [N X]=hist(y(:),10); %plot all the data figure,clf,hb...

14 días ago | 1

Answered
Looking for a matlab script that extracts data from a plot figure ( here 2D contours from Covariance matrix or Markov chains) and reproduce the original figure
your graph is a bit messy with text and lines that denote items. here is a quick example that may push you along. It'll need a...

14 días ago | 0

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Answered
Scientific notation at y-axis with yticks/yticklabels
from the looks of it the desired state is also plotting in a log10. you can change the current axis by set(gca,'yscale','log'...

15 días ago | 0

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Answered
Find the indices of the imaginary element of the matrix
you can do a comparison to the real(A) like A=[1 2 3; 4+i 5 6-i; 7 8+i 9] [row col]=find(A~=real(A)) ...

15 días ago | 0

Answered
How to make the code efficient?
You can do things all at once cine you're not dependent on previous values. n=4 x=[0:n-1]; y=[0:n-1]; k = 0; %%Orig_code ...

15 días ago | 0

Answered
Double sigma with exception case
in your nested forloop you can put a check in for if j==i then continue. you do have a check up there with i~=j which should w...

15 días ago | 0

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Answered
Remove shadow and unwanted background
to get your started you can see that the tissue and the shadow area have similar values in all the color channels. you can do a...

15 días ago | 0

Answered
How do I plot the upper view of a matrix and represent the intensity color?
Here is an example of what i'm thinking you're doing. Not sure what you're doing with the weighted average but i think i did so...

19 días ago | 1

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Answered
How to vertically and horizontally scan an image to store a coordinates (positions) of the elements having values other than 255.
do you need to "scan" in a for loop or are you just looking for the positions of the colors? if you don't need to scan in a for...

19 días ago | 0

Answered
How to plot an equation qith specific data range?
For this you can use the function ylim() clc clear x=0:5:100; y=3*x+10; y1=4*x+5; plot(x,y) hold on plot(x,y1) ylim([25...

20 días ago | 0

Answered
How to include function in legend
do you need to use latex as just using the default tex? as latex uses $ for markup of symbols i don't know if it'll take the sy...

20 días ago | 1

Answered
Having trouble with looping through fields in a struct
primarily its because of the data.t = zeros(length(list)); data.p = zeros(length(list)); where you've set the t and p to be ...

21 días ago | 0

Answered
how to add a label to a contourf plot next to colourbar?
you can set a ylabel by passing the colorbar handles into ylabel [X,Y] = meshgrid(1:12,1:24); Z = sin(X) + cos(Y); figure(1),...

21 días ago | 1

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Answered
Plotting streamlines from a dataset (x,y,u,v)
So, meshgrid generates a grid of x and grid of y values so index wise you get the xy pair-combo. usually very useful when you're...

21 días ago | 1

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