Convert decimal and negative values to integers

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Lev Mihailov 2022-7-4

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回答： Rik 2022-7-4

There are x and y coordinates that I need to convert to integer values while preserving the meaning of the graph

a = 0:pi/100:2*pi;
x=cos(a);
y = sin(x);
plot(x,y) % first graph
% plot(a,y) % second graph

Thanks in advance

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Dyuman Joshi 2022-7-4

Ok. So, What is it that you are trying to do in the first place? How did you come up with the conversions you mentioned above?

Lev Mihailov 2022-7-4

@Dyuman Joshi take min and max values, create an array, from -5.4 ; 1.2 to 4.5, fill array from 1 to n(up to 4), where 1 is the smallest value and 4 is the maximum

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回答（2 个）

Matt J 2022-7-4

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Something like this, perhaps?

a = 0:pi/100:2*pi;

x=cos(a);

y = sin(x);

fcn=@(z)round(rescale(z,0,intmax('uint16')));

plot(fcn(a),fcn(y))

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Rik 2022-7-4

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Since all your values are between -1 and 1, you need a method to discretize your data to some arbitrary (but repeatable) indices. You have two general options:

Have a linear lookup table. This will map all numbers lineraly to the closest integer.
Have a non-linear lookup table. This allows you to decide what data ranges should have more precision.

Below I will implement the simplest version of option 1 I can think of. If you want to increase performance, interp1 may be required.

discretize_values([-1 0 1],3)
ans = 1×3
     1     2     3

Now we can apply this to your curve. What I show here is how you can set the precision to influence how jagged your graph will look. Set a higher number for a smoother curve. The mapping back to non-integers should of course be removed if you are planning to use this for indexing.

a=linspace(0,2*pi,200);x=cos(a);y=sin(a);

plot(a,y)

hold on

precision=20;

y2=discretize_values(y,precision);

y2=2*((y2-1)/(precision-1))-1; % map back to non-integers

plot(a,y2)

hold off