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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

2 Downloads

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 (2019). addFitLine (https://www.mathworks.com/matlabcentral/fileexchange/26323-addfitline), MATLAB Central File Exchange. Retrieved .

Comments and Ratings (1)

Updates

1.31.0.0

clarify what this function does

1.3.0.0

Correct indexing bug

1.2.0.0

the polynomial fit was not return plot handles

1.1.0.0

Improved error checking: removes text and patch elements before acquiring plot data.
Added ability to fit higher order polynomials using polyfit and polyval.

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