addFitLine

A convenience function to superimpose a polynomial fit to already plotted data

** 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