Mapping Toolbox™

maptrimp - Trim polygons to latitude-longitude quadrangle

Syntax

[latTrimmed,lonTrimmed] = maptrimp(lat,lon,latlim,lonlim)

[latTrimmed,lonTrimmed] = maptrimp(lat,lon,latlim,lonlim) trims the polygons in lat and lon to the quadrangle specified by latlim and lonlim. latlim and lonlim are two-element vectors, defining the latitude and longitude limits respectively. lat and lon must be vectors that represent valid polygons.

Remarks

maptrimp conditions the longitude limits such that:

• lonlim(2) always exceeds lonlim(1)

• lonlim(2) never exceeds lonlim(1) by more than 360

• lonlim(1) < 180 or lonlim(2) > -180

• Should the quandrangle span the Greenwich meridian, then that meridian appears at longitude = 0.

Examples

Make two polygons using the scircle1 function, and display them:

[latTrimmed,lonTrimmed] = scircle1([0 0]',[-90 90]',[70 70]');
axesm('pcarree','Grid','on',...
      'MeridianLabel','on','ParallelLabel','on')
h = fillm(latTrimmed,lonTrimmed,'green');

Now trim the data to lie between 80ºS and 45ºN latitude, and 120ºW and 0º longitude. The coordinates are in two-column arrays coming out of scircle1, which you must first turn into NaN-delimited vectors:

latTrimmed = [latTrimmed; NaN NaN];
lonTrimmed = [lonTrimmed; NaN NaN];
[lat,lon] = maptrimp(latTrimmed(:),lonTrimmed(:),... 
            [-80 45],[-120 0]);
clmo(h)
fillm(lat,lon,'green')

Notice that the patch face to the east, lying completely outside the allowed area, was removed. The western patch was trimmed to the required area.

See Also

maptriml, maptrims

maptriml

maptrims