pygmt.grdcut
- pygmt.grdcut(grid, **kwargs)[source]
Extract subregion from a grid.
Produce a new
outgrid
file which is a subregion ofgrid
. The subregion is specified withregion
; the specified range must not exceed the range ofgrid
(but seeextend
). If in doubt, runpygmt.grdinfo
to 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 giveprojection
for oblique projections to determine the corresponding rectangularregion
that will give a grid that fully covers the oblique domain.Full option list at https://docs.generic-mapping-tools.org/6.5/grdcut.html
Aliases:
G = outgrid
J = projection
N = extend
R = region
S = circ_subregion
V = verbose
Z = z_subregion
f = coltypes
- Parameters:
grid (str or xarray.DataArray) –
Name of the input grid file or the grid loaded as a
xarray.DataArray
object.For reading a specific grid file format or applying basic data operations, see https://docs.generic-mapping-tools.org/6.5/gmt.html#grd-inout-full for the available modifiers.
outgrid – Name of the output netCDF grid file. If not specified, will return an
xarray.DataArray
object. For writing a specific grid file format or applying basic data operations to the output grid, see https://docs.generic-mapping-tools.org/6.5/gmt.html#grd-inout-full for the available modifiers.projection (str) – projcode[projparams/]width|scale. Select map projection.
region (str or list) – xmin/xmax/ymin/ymax[+r][+uunit]. Specify the region of interest.
extend (bool or float) – Allow grid to be extended if new
region
exceeds existing boundaries. Give a value to initialize nodes outside current region.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.
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 algorithms)
i - Informational messages (same as
verbose=True
)c - Compatibility warnings
d - Debugging messages
coltypes (str) – [i|o]colinfo. Specify data types of input and/or output columns (time or geographical data). Full documentation is at https://docs.generic-mapping-tools.org/6.5/gmt.html#f-full.
- Return type:
- Returns:
ret – Return type depends on whether the
outgrid
parameter is set:xarray.DataArray
ifoutgrid
is not setNone if
outgrid
is set (grid output will be stored in file set byoutgrid
)
Example
>>> import pygmt >>> # Load a grid of @earth_relief_30m data, with a longitude range of >>> # 10° E to 30° E, and a latitude range of 15° N to 25° N >>> grid = pygmt.datasets.load_earth_relief( ... resolution="30m", region=[10, 30, 15, 25] ... ) >>> # Create a new grid from an input grid, with a longitude range of >>> # 12° E to 15° E and a latitude range of 21° N to 24° N >>> new_grid = pygmt.grdcut(grid=grid, region=[12, 15, 21, 24])