How to plot non equally spaced data in an equally spaced fashion.

Question

RFR 2017-2-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/326049-how-to-plot-non-equally-spaced-data-in-an-equally-spaced-fashion

评论：楠赵 2020-12-4

采纳的回答： Star Strider

I am trying to plot some data:

x=[10 50 100 500 1000 1500 2000 2500 3000]; %data points

y=[74.6 88.8 89.6 92.1 92.5 88.8 88.8 87.9 85.4]; %accuracy(%)

The problem I am facing is that I cannot plot the data in an equally-spaced grid plot (including the tick locations). This is an example of what I want to achieve:

Thanks for your help in advance. Raul

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Answer 1

Star Strider 2017-2-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/326049-how-to-plot-non-equally-spaced-data-in-an-equally-spaced-fashion#answer_255631

在 MATLAB Online 中打开

See if this does what you want:

x=[10 50 100 500 1000 1500 2000 2500 3000]; %data points
y=[74.6 88.8 89.6 92.1 92.5 88.8 88.8 87.9 85.4]; %accuracy(%)
xt = [10 50 100 500 1000 1500 2000 2500 3000 3500];
xv = 1:length(xt);
yv = interp1(x, y, xt, 'linear', 'extrap');             % Extrapolate The ‘3500’ Value
figure(1)
plot(xv, yv)                                            % Plot Interpolated Values Against ‘xv’
grid
set(gca, 'XTickLabel',xt)                               % Label Ticks As ‘xt’
ylabel('Accuracy (%)')

If you do not want to extrapolate to 3500, the code would be:

x=[10 50 100 500 1000 1500 2000 2500 3000]; %data points
y=[74.6 88.8 89.6 92.1 92.5 88.8 88.8 87.9 85.4]; %accuracy(%)
xv = 1:length(x);
figure(1)
plot(xv, y)                                             % Plot Interpolated Values Against ‘xv’
grid
set(gca, 'XTickLabel',x)                                % Label Ticks As ‘xt’
ylabel('Accuracy (%)')

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Star Strider 2020-4-20

Thank you!

楠赵 2020-12-4

I use the script you suggest to plot the figure and I got the figure like this, now I want to present the value from "x" not from "xv", how can I set x axis value from "x" ? this is what I have now:

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Answer 2

KSSV 2017-2-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/326049-how-to-plot-non-equally-spaced-data-in-an-equally-spaced-fashion#answer_255621

在 MATLAB Online 中打开

x=[10 50 100 500 1000 1500 2000 2500 3000]; %data points
y=[74.6 88.8 89.6 92.1 92.5 88.8 88.8 87.9 85.4]; %accuracy(%)
N = 100 ;
xi = linspace(min(x),max(x),N) ;
yi = interp1(x,y,xi) ;
plot(x,y,'r') ;
hold on
plot(xi,yi,'.b')

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RFR 2017-2-21

Thanks for your answer, but your solution doesn't produce a equally spaced graph. For x(1)=10, x(2)=50, and x(3)=100, the distance between points is not equally spaced as the rest of the data (=500). I need to plot all the points with the same distance in the x axis like the sample figure. Thanks.

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