plot

Plot cfit or sfit object

Syntax

plot(sfit)

plot(sfit, [x, y], z)

H = plot(sfit, ..., Name,Value)

H = plot(sfit, ...)

plot(cfit)

plot(cfit,x,y)

plot(cfit,x,y,DataLineSpec)

plot(cfit,FitLineSpec,x,y,DataLineSpec)

plot(cfit,x,y,outliers)

plot(cfit,x,y,outliers,OutlierLineSpec)

plot(...,ptype,...)

plot(...,ptype,level)

H = plot(...)

Description

Note

These syntaxes are available for surfaces, or sfit objects.

plot(sfit) plots the sfit object over the range of the current axes, if any, or otherwise over the range stored in the fit.

plot(sfit, [x, y], z) plots z versus x and y and plots sfit over the range of x and y.

H = plot(sfit, ..., Name,Value) selects which way to plot the surface fit object sfit.

H = plot(sfit, ...) returns a vector of handles of the plotted objects.

Note

These syntaxes are available for curves, or cfit objects.

plot(cfit) plots the cfit object over the domain of the current axes, if any. If there are no current axes, and fun is an output from the fit function, the plot is over the domain of the fitted data.

plot(cfit,x,y) plots cfit together with the predictor data x and the response data y.

plot(cfit,x,y,DataLineSpec) plots the predictor and response data using the color, marker symbol, and line style specified by the DataLineSpec formatting character vector.

plot(cfit,FitLineSpec,x,y,DataLineSpec) plots fun using the color, marker symbol, and line style specified by the FitLineSpec formatting character vector, and plots x and y using the color, marker symbol, and line style specified by the DataLineSpec formatting character vector.

plot(cfit,x,y,outliers) plots data indicated by outliers in a different color. outliers can be an expression describing a logical vector, e.g., x > 10, a vector of integers indexing the points you want to exclude, e.g., [1 10 25], or a logical array where true represents an outlier. You can create the array with excludedata.

plot(cfit,x,y,outliers,OutlierLineSpec) plots outliers using the color, marker symbol, and line style specified by the OutlierLineSpec.

plot(...,ptype,...) uses the plot type specified by ptype.

plot(...,ptype,level) plots prediction intervals with a confidence level specified by level.

Note

This syntax is available for both curves and surfaces.

Plot types can be single or multiple, with multiple plot types specified as a cell array of character vectors. With a single plot type, plot draws to the current axes and can be used with commands like hold and subplot. With multiple plot types, plot creates subplots for each plot type.

H = plot(...) returns a vector of handles to the plotted objects.

Examples

Plot data, outliers, and the results of the fits using the plot function

This example shows how to plot the data, the outliers, and the results of three fit objects with different colors and line styles.

Create a baseline sinusoidal signal.

xdata = (0:0.1:2*pi)'; 
y0 = sin(xdata);

Add noise to the signal with non-constant variance.

% Response-dependent Gaussian noise
gnoise = y0.*randn(size(y0));

% Salt-and-pepper noise
spnoise = zeros(size(y0)); 
p = randperm(length(y0));
sppoints = p(1:round(length(p)/5));
spnoise(sppoints) = 5*sign(y0(sppoints));

ydata = y0 + gnoise + spnoise;

Fit the noisy data with a baseline sinusoidal model.

f = fittype('a*sin(b*x)'); 
fit1 = fit(xdata,ydata,f,'StartPoint',[1 1]);

Identify “outliers” as points at a distance greater than 1.5 standard deviations from the baseline model, and refit the data with the outliers excluded.

fdata = feval(fit1,xdata); 
I = abs(fdata - ydata) > 1.5*std(ydata); 
outliers = excludedata(xdata,ydata,'indices',I);

fit2 = fit(xdata,ydata,f,'StartPoint',[1 1],...
           'Exclude',outliers);

Compare the effect of excluding the outliers with the effect of giving them lower bisquare weight in a robust fit.

fit3 = fit(xdata,ydata,f,'StartPoint',[1 1],'Robust','on');

Plot the data, the outliers, and the results of the fits.

plot(fit1,'r-',xdata,ydata,'k.',outliers,'m*') 
hold on
plot(fit2,'c--')
plot(fit3,'b:')
xlim([0 2*pi])

Plot the residuals for the two fits considering outliers.

figure 
plot(fit2,xdata,ydata,'co','residuals') 
hold on
plot(fit3,xdata,ydata,'bx','residuals')
hold off

Load data and fit a Gaussian, excluding some data with an expression, then plot the fit, data and the excluded points.

[x, y] = titanium;
f1 = fit(x',y','gauss2', 'Exclude', x<800);
plot(f1,x,y,x<800)

Input Arguments

sfit — Surface fit object

sfit

Fit object to plot, specified as an sfit object.

x — Data to plot

matrix

Data to plot, specified as a matrix with either one (curve fitting) or two (surface fitting) columns.

y — Data to plot

matrix

Data to plot, specified as a matrix with either one (curve fitting) or two (surface fitting) columns.

z — Data to plot

matrix

Data to plot, specified as a matrix with either one (curve fitting) or two (surface fitting) columns.

cfit — Curve fit object

cfit

Fit object to plot, specified as a cfit object.

outliers — Outlier data

expression | index vector | logical vector

• An expression describing a logical vector, e.g., x > 10.

• A vector of integers indexing the points you want to exclude, e.g., [1 10 25].

• A logical vector for all data points where true represents an outlier, created by excludedata.

For an example, see Exclude Points from Fit.

Data Types: logical | double

DataLineSpec — Line style, marker, and color for x and y

character vector | string

Line style, marker, and color used to plot the predictor data x and response data y, specified as a character vector or string containing symbols. The symbols can appear in any order. You do not need to specify all three characteristics (line style, marker, and color). For example, if you omit the line style and specify the marker, then the plot shows only the marker and no line.

Example: '--or' is a red dashed line with circle markers

Line Style	Description
-	Solid line (default)
--	Dashed line
:	Dotted line
-.	Dash-dot line

Marker	Description
o	Circle
+	Plus sign
*	Asterisk
.	Point
x	Cross
s	Square
d	Diamond
^	Upward-pointing triangle
v	Downward-pointing triangle
>	Right-pointing triangle
<	Left-pointing triangle
p	Pentagram
h	Hexagram

Color	Description
y	yellow
m	magenta
c	cyan
r	red
g	green
b	blue
w	white
k	black

FitLineSpec — Line style, marker, and color for the function

character vector | string

Line style, marker, and color used to plot the cfit function, specified as a character vector or string containing symbols. The symbols can appear in any order. You do not need to specify all three characteristics (line style, marker, and color). For example, if you omit the line style and specify the marker, then the plot shows only the marker and no line.

Example: '--or' is a red dashed line with circle markers

Line Style	Description
-	Solid line (default)
--	Dashed line
:	Dotted line
-.	Dash-dot line

Marker	Description
o	Circle
+	Plus sign
*	Asterisk
.	Point
x	Cross
s	Square
d	Diamond
^	Upward-pointing triangle
v	Downward-pointing triangle
>	Right-pointing triangle
<	Left-pointing triangle
p	Pentagram
h	Hexagram

Color	Description
y	yellow
m	magenta
c	cyan
r	red
g	green
b	blue
w	white
k	black

OutlierLineSpec — Line style, marker, and color for the outliers

character vector | string

Line style, marker, and color used to plot the outliers, specified as a character vector or string containing symbols. The symbols can appear in any order. You do not need to specify all three characteristics (line style, marker, and color). For example, if you omit the line style and specify the marker, then the plot shows only the marker and no line.

Example: '--or' is a red dashed line with circle markers

Line Style	Description
-	Solid line (default)
--	Dashed line
:	Dotted line
-.	Dash-dot line

Marker	Description
o	Circle
+	Plus sign
*	Asterisk
.	Point
x	Cross
s	Square
d	Diamond
^	Upward-pointing triangle
v	Downward-pointing triangle
>	Right-pointing triangle
<	Left-pointing triangle
p	Pentagram
h	Hexagram

Color	Description
y	yellow
m	magenta
c	cyan
r	red
g	green
b	blue
w	white
k	black

ptype — Plot type

'fit' | 'predfunc' | 'predobs' | 'residuals' | 'stresiduals' | 'deriv1' | 'deriv2' | 'integral'

Plot type, specified as one of these supported types:

• 'fit' — Data and fit (default)

• 'predfunc' — Data and fit with prediction bounds for the fit

• 'predobs' — Data and fit with prediction bounds for new observations

• 'residuals' — Residuals

• 'stresiduals' — Standardized residuals (residuals divided by their standard deviation)

• 'deriv1' — First derivative of the fit

• 'deriv2' — Second derivative of the fit

• 'integral' — Integral of the fit

level — Confidence level

0.95 (default) | positive scalar in the range (0,1)

Level of confidence of the prediction intervals, specified as a scalar between 0 and 1.

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: 'Exclude',[1 10 25],'Level',0.95

'Exclude' — Plot excluded data in different color

expression | index vector | logical vector | empty

Excluded data points to plot in a different color, specified as the comma-separated pair consisting of 'Exclude' and one of:

• An expression describing a logical vector, e.g., x > 10.

• A vector of integers indexing the points you want to exclude, e.g., [1 10 25].

• A logical vector for all data points where true represents an outlier, created by excludedata.

For an example, see Exclude Points from Fit.

Data Types: logical | double

'Style' — Option to plot the surface fit object sfit

'Surface' (default) | 'PredFunc' | 'PredObs' | 'Residuals' | 'Contour'

Way to plot the surface fit object sfit, specified as the comma-separated pair consisting of 'Style' and one of:

• 'Surface' Plot the fit object as a surface (default)

• 'PredFunc' Surface with prediction bounds for function

• 'PredObs' Surface with prediction bounds for new observation

• 'Residuals' Plot the residuals (fit is the plane Z=0)

• 'Contour' Make a contour plot of the surface

'Level' — Confidence level

scalar

Confidence level used in the plot, specified as the comma-separated pair consisting of 'Level' and a positive scalar less than 1. The default value is 0.95, for 95% confidence. This option only applies to the 'PredFunc' and 'PredObs' plot styles.

'XLim' — x-axis limit

scalar | vector

Limits of the x-axis used for the plot, specified as the comma-separated pair consisting of 'XLim' and a scalar or vector. By default the axes limits are taken from the data, XY. If no data is given, then the limits are taken from the surface fit object, sfit.

'YLim' — y-axis limit

scalar | vector

Limits of the y-axis used for the plot, specified as the comma-separated pair consisting of 'YLim' and a scalar or vector. By default the axes limits are taken from the data, XY. If no data is given, then the limits are taken from the surface fit object, sfit.

'Parent' — Handle of axes

Axes object

Handle of the axes, specified as the comma-separated pair consisting of 'Parent' and a value.

Output Arguments

H — Vector of handles

object array

Vector of handles to the plotted objects, returned as an object array.