Make distribution visible in scatter plots

I have two vectors, I3 and D, of the size 1000000x1. They are plotted against each other in a scatter plot (see PIplot1)

I want to know how many values I have. For example If you look to the far right of the figure. I dont know How many values are around y=50 or how many are around y=150.

I need to make the distribution visible somehow, but I do not know how to go about it.

plot(I3,D,'.','Color', [0 0.4470 0.7410]); 

Answer 1

[Adam Danz]

You can display the 2D binned density using histogram2.

Demo: The plot on the left and right contain the same data.

x = 1:105; 
ym = randn(800, numel(x)) .* linspace(2,35,numel(x)) + linspace(6,150,numel(x)) ; 
xm = repmat(x,size(ym,1),1); 

figure()
tiledlayout(1,2)
ax(1) = nexttile;
plot(x,ym,'b.')
grid on
axis tight

ax(2) = nexttile; 
histogram2(xm,ym,'DisplayStyle','tile')
axis tight
cb = colorbar(); 
ylabel(cb, 'bin count')

linkaxes(ax)

Also try setting BinMethod or or bin edges in histogram2.