Histogram distribution with two vectors

Hi there,

I have two separate vectors, one for vehicle power and another one for vehicle speed. I am trying to have a histogram to show a power vs speed distribution. I have attached an image to assist with understanding.

Thanks,

[Torsten]

I don't understand the graphics you included. Could you elaborate ?

[Naser Khan]

Hi,

I have two vectors for the two axes. I am essentially looking to have the frequency (y-axis) of the power at different speed (x-axis). The speeds can be spaced out in steps of 5 or 10.

My query is whether its possible to plot a histogram based on an X-Y plot?

Thanks

[Torsten]

And what is the solid line in the graph ? Is it a kind of regression line approximating the speed/frequency relationship ?

Answer 1

[Image Analyst]

Since you say "I have two vectors for the two axes. I am essentially looking to have the frequency (y-axis) of the power at different speed (x-axis). The speeds can be spaced out in steps of 5 or 10."

then your y vector is already the frequency (histogram) so no need to call histogram() because you've already done that. The histogram function can do the plotting for you, or if you'd rather plot the frequency as bars like your graphic showed, then you can use bar

bar(speedVector, frequencyVector);
grid on;

[Naser Khan]

I see, is there a way I can group my speed vector into segments so the x axis doesn’t become very long?

I believe this may require me to do normalising with a histogram?

Thanks

[Image Analyst]

Sure, when you got your y values (counts in each hisotgram bin), you could specify the bin edges if you wish.

% Specify which x values should be grouped into each bin
% by definining the edges (dividing lines) between bins.
edges = [-inf, 0:20:100, inf];
% Get the y values which is the frequency (count)
% of how many data points are in each bin.
[counts, edges] = histcounts(data, edges);
bar(edges(1:end-1), counts);
grid on;