plot large dataset with sample points

Hello,

I would like to plot 2 large datasets (for comparison) using only sample points from each set so that markers can be clear (say 50 points). How will I do this and how do I choose these points from each dataset?

Thanks

Answer 1

[Image Analyst]

If a subset of the points would illustrate the situation just as well as the complete set, why not just select some of them at random?

indexesToUse = randperm(totalNumberOfPoints, numberToUse);

[Sam Alex]

You mean use these indices in an array to get the values that correspond to them, or is there a faster way?

[Image Analyst]

Let's say that you have an array with 400,000 points and when you plot them all the graph becomes so cluttered that you can't really see what's going on. Well, perhaps you can see what's going on if you plot only 4,000 points instead of 400,000 points. With fewer points the graph will be far less cluttered and you can see better what's going on. That's what I mean.

[Sam Alex]

True, but these indices always taken at random or is there a way better to represent the data from your experience?

[Image Analyst]

They're not always taken at random, that's just one way. You could take just the first N of the points, though if there's a trend in the data you might want to take every 1000th point or so, like this dataSubSet = data(1:1000:end). Basically use whatever method that works for you.