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addFitLine

version 1.31.0.0 (2.14 KB) by Rob Campbell
A convenience function to superimpose a polynomial fit to already plotted data

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Updated 11 Jun 2016

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** What is it?
This convenience function allows you to quickly add a fit line to data after they have been plotted. e.g.
>> plot(myData)
>> out=addFitLine;
Add fit line returns the fit parameters and handles to the plot objects.

** Details
The stats toolbox is required for the 'linear' and 'quadratic' options only.

function out=addFitLine(poolFits,modelType,lineprops,ax)

Purpose
Add one or more fit lines to some or all data in axes "ax" or,
without ax specified, to the current axes.

Inputs
*poolFits [optional 0 by default] -
if 1 we fit a single line to all data series on the current
axes.
*modelType ['linear' by default] - If 'linear' it fits a straight line
using the regress function from the stats toolbox. If 'quadratic' it
fits a second-order polynomial using regress. The output from regress is
returned. If modelType is an integer, the function fit a polynomial of
this order using polyfit, which is not part of the stats toolbox. The
output of polyfit is then returned.
*lineprops [optional 'b-' by default]
*ax [optional - gca by default]

Outputs
out - the fit parameters and plot handles

Examples
clf
%Fit two seperate lines
subplot(1,3,1), hold on, x=-5:0.1:5;
y=1+1*x+randn(size(x))*2; plot(x,y,'.k')
y=2-4*x+randn(size(x))*2; plot(x,y,'.r')
H=addFitLine

%Fit one line to two sets of data
subplot(1,3,2), hold on
x=-5:0.2:0; y=0.3*x+randn(size(x))*2; plot(x,y,'.k')
x=0:0.2:5; y=0.3*x+randn(size(x))*2; plot(x,y,'.r')
H=addFitLine(1)

%Fit one quadratic
subplot(1,3,3)
x=-5:0.1:5;
y=2+0.3*x+0.5*x.^2+randn(size(x))*2;
plot(x,y,'.k')
addFitLine([],'quadratic')
OR:
addFitLine([],2)

Rob Campbell - December 2009

Cite As

Rob Campbell (2020). addFitLine (https://www.mathworks.com/matlabcentral/fileexchange/26323-addfitline), MATLAB Central File Exchange. Retrieved .

Comments and Ratings (1)

Alexandra Tautan

MATLAB Release Compatibility
Created with R2009a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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