Grouped bar plot in MATLAB based on column values in a table

Question

I want to plot a grouped bar graph like in the figure below:

I've included a mock-up of the data I'm using:

I want to group the bars by SampleSite, label them by SampleName, and color them by Category. I've tried the following code, and while it gives me something close to what I'm looking for, I'm unsure how to get the data grouped and colored by the column values.

y1= samples(MockUp_Data.SampleSite== "Site1", :);
y2= samples(MockUp_Data.SampleSite== "Site2", :);
y3= samples(MockUp_Data.SampleSite== "Site3", :);

y= [y1;y2;y3];
bar(y.Data)
set(gca, 'xticklabels', char(y.SampleName), 'fontweight', 'bold', 'fontsize', 12)

Answer 1

I want to group the bars by SampleSite, label them by SampleName, and color them by Category.

pivot your current "long" table into a "wide" table:

• One SampleSite (group) per row
• One Category (color) per column

P = pivot(MockUp_Data, ...
    'Rows', 'SampleSite', ...
    'Columns', 'Category', ...
    'DataVariable', 'Data')

% P =
%
%   3x5 table
%
%     SampleSite    Bulk    Coarse    Fine    Mud
%     __________    ____    ______    ____    ___
%
%      "Site 1"     4.5        6       2      3.1
%      "Site 2"     5.5      6.7       8       10
%      "Site 3"      12      3.3       2        5

Now we have x in column 1, y in columns 2:end, and legend entries in headers 2:end:

bar(P{:,1}, P{:,2:end})
legend(P.Properties.VariableNames{2:end})

---

Note that your text description and mock figure are flipped (former is grouped by SampleSite, latter is grouped by Category). To follow your mock figure, flip the rows and columns while pivoting:

P = pivot(MockUp_Data, ...
    'Rows', 'Category', ...
    'Columns', 'SampleSite', ...
    'DataVariable', 'Data')
bar(P{:,1}, P{:,2:end})
legend(P.Properties.VariableNames{2:end})