How do I extract data from MATLAB figures? (some error)
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I want to extract 'y data' value from a fig file.
I input the following code in Matlab R2018b:
ezplot('y*(0.6326*log(y)+4.419*y + 30.48) - 80*sin(x)^2',[-5 5 -1 4])
>> h= gcf;
axObjs = h.Children
dataObjs = axObjs.Children
x = dataObjs(1).XData
y = dataObjs(1).YData
but I get the value for 'x axis' and 'y axis'. I don't need y axis. I only want to get the value of y date.
No matter what i do i can't make this to work. It's very strange. Any help will be greatly appreciated. Thanks in advance.
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Ameer Hamza
2020-10-7
编辑：Ameer Hamza
2020-10-7
ezplot() is being depreciated. Also, it generates a contour object, which is not so helpful to extract the data. Use fimplicit instead.
f = fimplicit(@(x, y) y.*(0.6326*log(y)+4.419*y + 30.48) - 80*sin(x).^2, [-5 5 -1 4]);
h= gcf;
axObjs = h.Children;
dataObjs = axObjs.Children;
x = dataObjs(1).XData;
y = dataObjs(1).YData;
4 个评论
jaejin kim
2020-10-7
Ameer Hamza
2020-10-7
But x is a vector, and therefore, sin(x) is a vector. But I don't want to do matrix multiplication. I want to do element-wise square; therefore, I specified .^ to let MATLAB know element-wise multiplication. For terms
0.6326*log(y)
4.419*y
It is a scalar multiplying with vector. You can use both * or .* There is no difference. I just skipped them for convenience.
Read here for more details: https://www.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html
jaejin kim
2020-10-7
Ameer Hamza
2020-10-7
I am glad to be of help!
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