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How to get X and Y points (or function(s)) from a plotted line

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Addison Collins
Addison Collins on 16 Aug 2021
Commented: Addison Collins on 17 Aug 2021
Hello all,
So I have a instrument that provides a handful of X and Y points based up on bins from a histogram. I plotted the graphs in matlab and would like a way to pull points from curve that were not in the original vector of points used to plot.
Is there a way I can pull a set amount of points from the line (say 1000 or so) or to pull a function?
I am aware of the function getpoints, but it only pulls points that were use in the plot to begin with (as far as I know). I have attached example code. I would like to have more points than just the ones I input, so I wanted to pull them from the curve fitted to the inputted points.
clear;clc;close all
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Set plot stuff:
set(0,'DefaultLineLineWidth',1.5)
set(0,'DefaultLineMarkerSize',15)
set(0,'DefaultAxesFontSize',20)
set(0,'DefaultFigureColor',[1,1,1])
set(0,'DefaultTextFontSize',18)
set(0,'DefaultTextFontName','Times-Roman')
set(0,'DefaultAxesFontName','Times-Roman')
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
type = '3-6 µm';
experiment = 'base';
class = 'Small';
%% Base PSD
xData = [0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 6 6.4 6.8 7.2 7.6 8 8.4 8.8 9.2 9.6 10 10.4 10.8 11.2 11.6 12 12.4 12.8 13.2 13.6 14 14.4 14.8 15.2 15.6 16 16.4 16.8 17.2 17.6 18 18.4 18.8 19.2 19.6 20];
p3_base = [0 0.019 0.035 0.153 0.32 0.63 1.112 1.823 2.722 3.61 4.309 4.737 4.937 4.941 4.876 4.891 5.051 5.221 5.274 5.146 4.877 4.469 3.989 3.485 3.004 2.558 2.149 1.8 1.484 1.218 0.987 0.795 0.637 0.513 0.42 0.346 0.283 0.233 0.194 0.16 0.133 0.117 0.1 0.082 0.074 0.056 0.054 0.045 0.043 0.038 0.036];
yData = p3_base;
sizes = [];
tic
for i = 1:length(yData)
for j = 1:(yData(i)*1000)
sizes = [sizes xData(i)];
end
end
toc
%% q3 PSD
fig2 = figure('Renderer', 'painters', 'Position', [1300 10 947 900]);
plot(xData,smooth(q3_base),'color','black');
% daspect([1 1 1])
% title('3-6 µm Base PSD PDF')
title([class,' Glass Microspheres Base PSD PDF'])
xlabel('Particle diameter (µm)')
ylabel('Probability Density (%/µm)')

Accepted Answer

KSSV
KSSV on 17 Aug 2021
yData = smooth(q3_base) ;
% Interpolation
m = 100 ; % change this for required number of points
xi = linspace(min(xData),max(xData),m) ;
yi = interp1(xData,yData,xi) ;
plot(xData,YData,'b',xi,yi,'.r');

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