Extract subregion from a grid.
Produce a new outgrid file which is a subregion of grid. The subregion is specified with region; the specified range must not exceed the range of grid (but see extend). If in doubt, run
pygmt.grdinfoto check range. Alternatively, define the subregion indirectly via a range check on the node values or via distances from a given point. Finally, you can give projection for oblique projections to determine the corresponding rectangular region setting that will give a grid that fully covers the oblique domain.
Full option list at https://docs.generic-mapping-tools.org/latest/grdcut.html
G = outgrid
J = projection
N = extend
R = region
S = circ_subregion
V = verbose
Z = z_subregion
projection (str) – Required if this is the first plot command. Select map projection.
circ_subregion (str) –
'lon/lat/radius[unit][+n]'. Specify an origin (lon and lat) and radius; append a distance unit and we determine the corresponding rectangular region so that all grid nodes on or inside the circle are contained in the subset. If +n is appended we set all nodes outside the circle to NaN.
z_subregion (str) –
'[min/max][+n|N|r]'. Determine a new rectangular region so that all nodes outside this region are also outside the given z-range [-inf/+inf]. To indicate no limit on min or max only, specify a hyphen (-). Normally, any NaNs encountered are simply skipped and not considered in the range-decision. Append +n to consider a NaN to be outside the given z-range. This means the new subset will be NaN-free. Alternatively, append +r to consider NaNs to be within the data range. In this case we stop shrinking the boundaries once a NaN is found [Default simply skips NaNs when making the range decision]. Finally, if your core subset grid is surrounded by rows and/or columns that are all NaNs, append +N to strip off such columns before (optionally) considering the range of the core subset for further reduction of the area.
verbose (str) –
Select verbosity level [Default is w], which modulates the messages written to stderr. Choose among 7 levels of verbosity:
q - Quiet, not even fatal error messages are produced
e - Error messages only
w - Warnings [Default]
t - Timings (report runtimes for time-intensive algorthms);
i - Informational messages (same as “verbose=True”)
c - Compatibility warnings
d - Debugging messages
ret (xarray.DataArray or None) – Return type depends on whether the outgrid parameter is set:
xarray.DataArray if outgrid is not set
None if outgrid is set (grid output will be stored in outgrid)