Plotly graphs

I would like to welcome Chris Parmer of plot.ly, who will describe the integration of Plotly graphs and charts in Matlab. Unlike the open-source JFreeChart and Waterloo plotting libraries that were described here in the past, Plotly is a commercial (not open-source) service. Contact Plotly for the exact license terms and costs. However, as you can see below, there’s a demo account that you can freely use. While I do not directly endorse Plotly as a commercial operation, I love its beautiful visualizations and interactivity. I think MathWorks would be wise to copy ideas from Plotly to Matlab’s graphics library, esp. new chart types and the interactivity features. In the future I hope that either Plotly concepts get included in Matlab’s HG, or that Plotly plots become embeddable in Matlab GUI (or both).
Plotly is a new web-based graphing application. You can interactively make, style, analyze and share beautiful graphs. Here is an example (move your mouse over the graph to see the interactive effects): 

Creating Plotly graphs in Matlab

Plotly has a Matlab interface. From Matlab, you send data to plotly where it will be stored and made into a graph that you view in your browser. Let’s get started.

1. download the Plotly-Matlab API package.
    
2. Add folder and subfolders to your Matlab path:

   path_to_downloaded_folder = '/User/chris/Downloads/plotly'; % fill in with your path addpath(genpath(path_to_downloaded_folder))

   path_to_downloaded_folder = '/User/chris/Downloads/plotly'; % fill in with your path addpath(genpath(path_to_downloaded_folder))

3. Sign up through the API, or sign-in with a demo account:

   % To sign up, run: r = signup('my_desired_plotly_username', 'my_desired_plotly_username@my_email.com') % plotly generates a temp password and api_key for you signin(r.un, r.api_key); % then, sign in with your newly created account % OR to use the demo account, do: plotly_username = 'MATLAB_example' % a demo username you can use plotly_key = 'h5n38rzyjo' % a demo api key you can use signin(plotly_username, plotly_key)  % sign in to plotly

   % To sign up, run: r = signup('my_desired_plotly_username', 'my_desired_plotly_username@my_email.com') % plotly generates a temp password and api_key for you signin(r.un, r.api_key); % then, sign in with your newly created account % OR to use the demo account, do: plotly_username = 'MATLAB_example' % a demo username you can use plotly_key = 'h5n38rzyjo' % a demo api key you can use signin(plotly_username, plotly_key)  % sign in to plotly

4. Create a new chart using the API’s plotly function:

   % Here's a simple line chart example: >> x = linspace(0, 6*pi, 100); >> y1 = exp(-0.2*x).*sin(x); >> y2 = exp(-0.3*x).*sin(x); >> r = plotly(x,y1,x,y2) % call plotly instead of plot High five! You successfully sent some data to your account on plotly. View your plot in your browser at https://plot.ly/~MATLAB_example/3 or inside your plot.ly account where it is named 'plot from API (3)' ans = url: 'https://plot.ly/~MATLAB_example/3' message: [1x205 char] warning: [1x0 char] filename: 'plot from API (3)' error: [1x0 char]

   % Here's a simple line chart example: >> x = linspace(0, 6*pi, 100); >> y1 = exp(-0.2*x).*sin(x); >> y2 = exp(-0.3*x).*sin(x); >> r = plotly(x,y1,x,y2) % call plotly instead of plot High five! You successfully sent some data to your account on plotly. View your plot in your browser at https://plot.ly/~MATLAB_example/3 or inside your plot.ly account where it is named 'plot from API (3)' ans = url: 'https://plot.ly/~MATLAB_example/3' message: [1x205 char] warning: [1x0 char] filename: 'plot from API (3)' error: [1x0 char]

And here’s the graph that you just generated: https://plot.ly/~MATLAB_example/3
Note that the graph won’t actually appear in a Matlab figure, nor can it be viewed in Matlab’s limited built-in browser (web). Instead, you view all of your plots in your “real” web browser, at the URL that plotly has returned. You can also have Matlab automatically open up the browser by running dos(['open ' r.url]) on a Mac, or dos(['start ' r.url]) on Windows. Within a webpage, you can embed it using an iframe tag (as I have done in this article), as follows:

<iframe width="800" height="400" seamless="seamless" scrolling="no" src="https://plot.ly/~MATLAB_example/3"></iframe>

Here is a side-by-side comparison with the corresponding Matlab plot:

Customizing Plotly graphs

Every aspect of the plotly graph can be customized online. This means no more 500-line styling scripts! To open up the plot into the GUI, click the “Save a copy” button. You can also download the graphs to EPS, SVG, PNG, and PDF:

samples = randn(500,1); % 500 normally distributed samples
trace1 = struct('y', samples, ...
                'type', 'histogramy', ... % make a histogram type plot
                'histnorm', 'probability density'); % normalized by probability density distribution
trace2 = struct('x', linspace(-3,3,100), ...
                'y', 1./sqrt(2*pi)*exp(-linspace(-3,3,100).^2/2.), ...
                'fill', 'tozeroy') % "fill" the curve to the "zero-y" line i.e. make an area plot
response = plotly({trace1, trace2});  % => https://plot.ly/~MATLAB_example/5

x = linspace(0,6*pi,100);
trace1 = struct('x',x, 'y',sin(x).*exp(-0.3*x));
trace2 = struct('x',x, 'y',10*sin(x-2*pi/3).*exp(-0.3*x), 'yaxis','y2'); % this trace will correspond to 2nd y-axis, 'y2'
trace3 = struct('x',x, 'y',100*sin(x-4*pi/3).*exp(-0.3*x), 'yaxis','y3'); % this trace will correspond to 3rd y-axis, 'y3'
layout = struct('xaxis', struct('domain',[0,0.9]), ... % set x-axis to span 90% of plot width, like Matlab's 'Position' property
                'yaxis2', struct('anchor','x', 'side','right', 'overlaying','y'), ... % places another y-axis on the right side of the plot
                'yaxis3', struct('anchor','side', 'right','free', 'position',1.0, 'overlaying','y')) % places 3rd y-axis at 100% plot width
r = plotly({trace1, trace2, trace3}, struct('layout', layout));  % => https://plot.ly/~MATLAB_example/13
dos(['open ', r.url])

x1 = [1, 2, 3];  y1 = [2,3,4];
x2 = [20,30,40]; y2 = [3,4,5];
x3 = [2, 3, 4];  y3 = [600,700,800];
x4 = [4000,5000,6000]; y4 = [7000,8000,9000];
% build structs describing the plot traces and assigning data to axes
trace1 = struct('x',x1, 'y',y1);
trace2 = struct('x',x2, 'y',y2, 'xaxis','x2', 'yaxis','y');  % new x-axis but same y-axis as trace1; 'x2' is shorthand for 'xaxis2' below
trace3 = struct('x',x3, 'y',y3, 'xaxis','x',  'yaxis','y3'); % same x-axis as trace 1 but a new y-axis
trace4 = struct('x',x4, 'y',y4, 'xaxis','x4', 'yaxis','y4'); % new x-axis and new y-axis
% build a layout struct describing the layout of the different axes
xaxis =  struct('domain', [0, 0.45]); % let the first x-axis span the first 45% of the plot width
yaxis =  struct('domain', [0, 0.45]); % and let the first y-axis span the first 45% of the plot height
xaxis2 = struct('domain', [0.55, 1]); % and let the second axis span the latter 45% of the plot width
yaxis3 = struct('domain', [0.55,1]);
xaxis4 = struct('domain', [0.55, 1], 'anchor','y4'); % anchor axis vertical position to start of yaxis4
yaxis4 = struct('domain', [0.55, 1], 'anchor','x4'); % anchor axis horizontal position to start of xaxis4
layout = struct('xaxis',xaxis, 'yaxis',yaxis, 'xaxis2',xaxis2, 'yaxis3',yaxis3, 'xaxis4',xaxis4, 'yaxis4',yaxis4);
r = plotly({trace1,trace2,trace3,trace4}, struct('=> layout', layout))  % => https://plot.ly/~MATLAB_example/15
dos(['open ', r.url])

y1 = randn(50,1); y2 = rand(50,1);
r = plotly({struct('y',y1, 'type','box'), struct('y',y2, 'type','box')}) % => https://plot.ly/~MATLAB_example/17
dos(['open ', r.url])

r = plotly({struct('z',randn(50,50), 'type','heatmap')}) % => https://plot.ly/~matlab_example/18
dos(['open ', r.url])

Additional resources

• Online-documentation: https://plot.ly/api/MATLAB/
• An online gallery: https://plot.ly/api/MATLAB/gallery/
• Plotly File Exchange utility: http://www.mathworks.com/matlabcentral/fileexchange/42202-plotly-api
• The Matlab interface is open source on GitHub: https://github.com/plotly/MATLAB-api (note that the plotly engine is not open-source, only the API)
• Plotly’s homepage: https://plot.ly/
• Email: chris [at] plot [dot] ly