How to specify Hexadecimal Color Code on a fit line?

I have been able to present a fit line through a scatter plot by writting the following, in a for loop:

t_array: time array

P2P: data array

colour_shape = {'b', 'y' , 'g', 'r'};
for x0 = 1:4
    trial2 = colour_shape{x0};
    fit_line = fit(t_array, P2P, 'exp2'); %fit function

    figure(5) 
    p(x0) = plot(t_array, P2P, 'o');
    hold on   
    plot(fit_line,  trial2)
end

The colours that MATLAB automatically chose for the scatter plot, p(x0) = plot(t_array, P2P, 'o') , are the default ones and are the ideal. I tried using these same default colour for plotting the fit_line, by substituting the colour_shape cell values by:

colour_shape = {'#0072BD' , '#EDB120' , '#77AC30' , '#A2142F'};

But I get the following statement: "Invalid color or line style."

How can I use these colour for the best-fit line? How can I also increase the thickness of these lines?

[Rik]

You can set any RGB triplet as the Color property of a line object. I don't remember whether it should be 0-255 or 0-1, you'll have to look up the documentation for plot or line.

[Goncalo Costa]

I have also tried to do that, that would be in terms of 0 -255.

To verify if that approach worked I opted to only select a single colour (given in some other example here on the website) and wrote

colour_shape = '#FF0000';
trial2 = sscanf(colour_shape(2:end),'%2x%2x%2x',[1 3])/255 

for x0 = 1:4
    trial2 = colour_shape{x0};
    fit_line = fit(t_array, P2P, 'exp2'); %fit function
    figure(5) 
    p(x0) = plot(t_array, P2P, 'o');
    hold on   
    plot(fit_line, 'Color' , trial2)
end

But this still didn't work and the message below is shown. Any more help would be very much appreciated.

"Brace indexing is not supported for variables of this type."

[Stephen23]

What do you expect this indexing:

colour_shape{x0}

to achieve on a 1x9 character vector?

[Goncalo Costa]

The way I hae written it on my previous comment worked, I had a mistake in the way it was written on MATLAB, but not on the way it was written here, my apologies for that.

Answer 1

[Santosh Fatale]

Hi Goncalo,

I understand that you want to plot datapoints in figure and fit a line using “fit” function from “Curve Fitting Toolbox”. You want to customize the colour of the fitted line using Hex-Code.

The following code snippet gives the desired result.

colour_shape = {'#0072BD', '#EDB120', '#77AC30', '#A2142F'};
for x0 = 1:4
    trial2 = colour_shape{x0};
    fit_line = fit(t_array, P2P, 'exp2'); %fit function
    
    figHandle = plot(fit_line,t_array, P2P,'o'); % fit_line and datapoints can be plotted using single command.
    set(figHandle(2),'Color',colour_shape{x0});
end

Note that t_array and P2P must be a column vector or matrix for passing as inputs to the “fit” function. In the above code, figHandle is the handle to the graphics object created using plot function.

>> figHandle
figHandle = 
2×1 Line array:
Line    (data)
Line    (fitted curve)

For more info, refer to the documentation of plot function with Curve Fitting Toolbox.

Answer 2

[Jan]

This is working in modern Matlab versions:

plot(1:10, rand(1, 10), 'Color', '#A2142F')

For older versions:

color = uint8(sscanf('#A2142F', '#%2x%2x%2x'));
plot(1:10, rand(1, 10), 'Color', color);