Sean's pick this week is gramm by Pierre Morel.  

Contents

Grouped Plotting

Have you ever wanted to plot things based on a group or a category? If so, Pierre's gramm should likely be your friend. Gramm stands for "Grammar of Graphics for MATLAB" which is inspired from this book. This tool allows for plotting and statistics based on grouping data.

Simple Example

Here is a simple example using fuel economy data that I have stored in a table called CarData. We're going to fit fuel economy to rated horsepower based on whether it is a car or a truck operating in the city or on the highway.

g = gramm('x',CarData.RatedHP','y',CarData.MPG,...
    'Color',CarData.City_Highway,...
    'Marker',CarData.Car_Truck);
facet_grid(g,CarData.City_Highway,CarData.Car_Truck,'scale','fixed');
geom_point(g);
stat_fit(g,'fun',@(a,b,c,x)a.*x.^b+c,'disp_fit',true,'StartPoint',[1 1 21]);
set_names(g,'x','Horsepower','y','MPG','column','Vehicle class','color','Driving condition','column','','row','');
draw(g);

We can now look at the model results of the separate fits:

g.results.stat_fit.model

ans = 
     General model:
     ans(x) = a.*x.^b+c
     Coefficients (with 95% confidence bounds):
       a =      -331.9  (-2840, 2177)
       b =     0.03341  (-0.1808, 0.2476)
       c =       419.4  (-2125, 2964)
ans = 
     General model:
     ans(x) = a.*x.^b+c
     Coefficients (with 95% confidence bounds):
       a =      -82.91  (-684.2, 518.4)
       b =     0.08624  (-0.3401, 0.5125)
       c =       150.1  (-503.6, 803.8)
ans = 
     General model:
     ans(x) = a.*x.^b+c
     Coefficients (with 95% confidence bounds):
       a =      -219.4  (-1350, 911.2)
       b =     0.05282  (-0.1593, 0.265)
       c =       326.3  (-842.9, 1496)
ans = 
     General model:
     ans(x) = a.*x.^b+c
     Coefficients (with 95% confidence bounds):
       a =      -65.33  (-1142, 1011)
       b =     0.08805  (-0.8959, 1.072)
       c =       131.9  (-1041, 1305)

Rather than trying to come up with a bunch of examples on my own, I went ahead and opened Pierre's example script as a Live Script and exported it to html. His example script provides a lot of different examples for the comprehensive range of capabilities. In additon to the examples, there is also a PDF "cheat sheet" to learn the common parameters you can add. While working with gramm, I kept it open the entire time.

Suggestions

Author Update Pierre released a new version of gramm at the beginning of May 2016 that has implemented the suggestions below!  For the third suggestion, you can now parent it to a figure, uitab or uipanel. A few suggestions for Pierre:

Comments

Give it a try and let us know what you think here or leave a comment for Pierre.

Get the MATLAB code

Published with MATLAB® R2016a