Not really understanding why cdata isn't working

This code I have is giving me an error saying cdata is not a recognizable function. If anyone could help me understand why, it would really be helpful please.

clc;
clear;
close all;


DataTbl=readtable('N303_M.2.csv');

[Ro,Co]=size(DataTbl);

Data=table2array(DataTbl);

latitude=Data(:,1);
longitude=Data(:,2);
altitude=Data(:,3);

h = heatmap(cdata,'ColorLevels', 5);

h.XLabel = 'Longitude';
h.YLabel = 'Latitude';

Answer 1

[Star Strider]

The ‘cdata’ matrix only exists if you create it.

See the heatmap documentation section Create Heatmap from Matrix Data for details, since that appears to be what you’re referring to.

Answer 2

[Walter Roberson]

heatmap can be called in two different ways.

If you call it with a 2d numeric array, then a map is constructed that is the same size as the array and the array values are relative intensities. This is the mode that your code is trying to use.

If, however, you have a table() object, then you can pass in the table and the names of two variables, and heatmap() will count all of the times that each combination of the two variables occurs and will create a heatmap of the results. This might be the form that you actually need.