Geospatial mapping: map one state from data from the continental US

Hi,

I'm using Matlab 2014b. I have a gridded data for the entire US in a matrix (621 x 1405). I am calling this matrix 'data'. I made a georasterref using the following code.

R = georasterref();
R.LatitudeLimits=[ 24.062499 49.9375];
R.LongitudeLimits=[-125.0208333 -66.4792];
R.RasterSize=[621 1405]

I can plot the continental US using this code.

geoshow(data, R, 'DisplayType','Surface')

I just want to plot the data that are contained with the CA boarders. I am pretty sure I need to use the filterm function. I have tried multiple different approaches. Some examples of my attempts are below.

Example 1

[latout,lonout,indx] = filterm(californiahi.Lat,californiahi.Lon,data,R)

Example 2

Lat=24.062499:.0416668:49.9375;
Long=-125.0208333:.0416668:-66.4792;
[flat,flon,index]=filterm(Lat,Long,californiahi,data,'allowed');

Any guidance on how to plot only the data in the CA boarders would be very much appreciated.

THANK YOU in advance. Julie

Answer 1

[Chad Greene]

Use inpolygon. If you have lat/lon data given by ( latdata, londata) and California outline given by ( latCA, lonCA),

in = inpolygon(londata,latdata,lonCA,latCA);

will return a matrix the same size as latdata. It will have ones for any data within California's borders, zeros otherwise. Then you can use plotm(latdata(in),londata(in) or pcolorm(latdata(in),londata(in),Zdata(in) or what-have-you.