How to generate triangular heatmap using matlab?

I need to make a trinagular matrix like the image below:

Any idea to generate using matlab?

The data I have is a table shown below:

How can I make the heatmap directly from above table without the need to make a matrix?

Answer 1

[KALYAN ACHARJYA]

data=tril(randi(100,[15,15]));
imagesc(data);
colormap summer
colorbar

Plese DO modification and addition(labels) as per required

Answer 2

[Frederick Vonberg]

One other alternative, if you want to retain some of the functionality associated with heatmap, is to replace replace all values above the diagonal with NaN and then set all NaNs to white. The result will (look like) a triangular heatmap.

data = randi(100, [15, 15]);
ii = ones(size(data));
idx = tril(ii);
data(~idx) = nan;
heatmap(data, 'MissingDataColor', 'w', 'GridVisible', 'off', 'MissingDataLabel', " ")

Granted you now have an issue with an empty "missing data" label on the colorbar. You may find it preferable to set 'ColorbarVisible' to 'off', but now you have the options provided by the heatmap function.