How to create a frequency distribution table

I have hourly recorder data for wave height and wave direction, so I want to create a frequency distribution table for this data by grouping it.

Maybe the attached picture explains what I need exactly.

Appreciate your help .

[Mathieu NOE]

Look for heatmap topics / examples on this forum and on the File exchange

Answer 1

[Drew]

From the raw data, you can use histcounts2 (https://www.mathworks.com/help/matlab/ref/histcounts2.html) to get the number of data points that fall in each joint occurrence bin. You can control the bin edges, etc, if desired. A similar question was answered with histcounts2: https://www.mathworks.com/matlabcentral/answers/268207-how-to-bin-data-based-on-two-variables-to-create-a-joint-occurance-table?s_tid=prof_contriblnk

Once you have the counts, you can normalize them and visualize them in various ways, including with heatmap, hist3, or with histogram2. If using a heatmap, you can adjust the heatmap chart properties with https://www.mathworks.com/help/matlab/ref/matlab.graphics.chart.heatmapchart-properties.html

% jotw = Joint Occurrence Table for Waves
% This is data from the image above
jotw=[1.1 0.3 0 0 0 0 0 0 0 0.1 0.4 1.4
1.8 1.2 0.3 0.1 0 0.7 0 0 0.1 0.1 2.1 3.1
1.8 1.9 0.3 0 0 0 0 0 0 0.5 5.3 5.8
1.6 1.2 0 0 0 0 0 0 0 0.7 5.9 7.4
0.6 0.2 0 0 0 0 0 0 0 0.5 5.9 6.0
0.4 0.2 0 0 0 0 0 0 0 0.6 4.0 6.6
0.3 0 0 0 0 0 0 0 0 0.5 2.8 6.0
0.2 0 0 0 0 0 0 0 0 0.5 2.3 2.9
0 0 0 0 0 0 0 0 0 0.4 2.1 2.0
0 0 0 0 0 0 0 0 0 0.2 1.2 1.1
0 0 0 0 0 0 0 0 0 0.2 1.0 0.9
0 0 0 0 0 0 0 0 0 0 0.8 0.4
0 0 0 0 0 0 0 0 0 0 0.6 0.2
0 0 0 0 0 0 0 0 0 0 0.4 0.2
0 0 0 0 0 0 0 0 0 0 0.4 0.1
0 0 0 0 0 0 0 0 0 0 0.7 0.3
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0];

% Change zeros to NaNs so that the zeros can be made invisible
jotw(jotw==0)=NaN;

h=heatmap(jotw);

% Adjust the label and color of the NaNs
h.MissingDataLabel="no data";
h.MissingDataColor=h.Colormap(1,:);

% Can alternately get these from the bin centers or bin edges if the data
% is from histcounts2
h.XData={'0','30','60','90','120','150','180','210','240','270','300','330'};
h.YData={'0.0-0.2','0.2-0.2','0.4-0.6','0.6-0.8','0.8-1.0','1.0-1.2','1.2-1.4', ...
    '1.4-1.6','1.6-1.8','1.8-2.0','2.0-2.2','2.2-2.4','2.4-2.6','2.6-2.8', ...
    '2.8-3.0','3.0-4.0','4.0-5.0','>5.0'};

% Add some labels
h.XLabel='Mean Wave Direction';
h.YLabel='Significant Wave Height (m)';
h.Title='% Occurrence of Wave Height and Wave Direction';