Find values within a contour and replace with nan

Hi,

I have a contour (bathymetry) line with a column of values x, y. I also have a dataset of chlorophyll values (XX,YY,Chl) scattered on the map. I would like find all the Chl values within the contour and replace with NaN. Is it also possible to choose a distance, say 3 km, outside the contour line and replace all those values with NaN?

Answer 1

[Adam Danz]

It sounds like the goal is to hide the scatter points under the contour in which case it would be easiest to use the (x,y) coordinates that define the contour to create a white patch that's plotted on top of the existing objects.

[akk]

I would like to average all the values after removing those inside the contour. I have tried using inpolygon, but for some reason there are still a few points left inside the contour.

[Image Analyst]

Can you upload data and code to reproduce your diagram? Make it easy for us to help you.

[Adam Danz]

In that case I would recommend inpolygon as you have discovered. If you want to remove all points within the larger contour, you should only use the (x,y) coordinates that define the outer contour and remove the coordinates that define the inner contours.

If you want to remove all points within the larger contour that are not within the inner contours, follow this example,

https://www.mathworks.com/help/matlab/ref/inpolygon.html#buanygl-3

If you're having further problems, provide more detail.