"""
grdclip - Change the range and extremes of grid values.
"""
from pygmt.clib import Session
from pygmt.helpers import (
GMTTempFile,
build_arg_string,
fmt_docstring,
kwargs_to_strings,
use_alias,
)
from pygmt.io import load_dataarray
__doctest_skip__ = ["grdclip"]
[docs]
@fmt_docstring
@use_alias(
G="outgrid",
R="region",
Sa="above",
Sb="below",
Si="between",
Sr="new",
V="verbose",
)
@kwargs_to_strings(
R="sequence",
Sa="sequence",
Sb="sequence",
Si="sequence",
Sr="sequence",
)
def grdclip(grid, **kwargs):
r"""
Set values in a grid that meet certain criteria to a new value.
Produce a clipped ``outgrid`` or :class:`xarray.DataArray` version of the
input ``grid`` file.
The parameters ``above`` and ``below`` allow for a given value to be set
for values above or below a set amount, respectively. This allows for
extreme values in a grid, such as points below a certain depth when
plotting Earth relief, to all be set to the same value.
Full option list at :gmt-docs:`grdclip.html`
{aliases}
Parameters
----------
{grid}
{outgrid}
{region}
above : str or list
[*high*, *above*].
Set all data[i] > *high* to *above*.
below : str or list
[*low*, *below*].
Set all data[i] < *low* to *below*.
between : str or list
[*low*, *high*, *between*].
Set all data[i] >= *low* and <= *high* to *between*.
new : str or list
[*old*, *new*].
Set all data[i] == *old* to *new*. This is mostly useful when
your data are known to be integer values.
{verbose}
Returns
-------
ret: xarray.DataArray or None
Return type depends on whether the ``outgrid`` parameter is set:
- :class:`xarray.DataArray` if ``outgrid`` is not set
- None if ``outgrid`` is set (grid output will be stored in file set by
``outgrid``)
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]
... )
>>> # Report the minimum and maximum data values
>>> [grid.data.min(), grid.data.max()]
[183.5, 1807.0]
>>> # Create a new grid from an input grid. Set all values below 1,000 to
>>> # 0 and all values above 1,500 to 10,000
>>> new_grid = pygmt.grdclip(grid=grid, below=[1000, 0], above=[1500, 10000])
>>> # Report the minimum and maximum data values
>>> [new_grid.data.min(), new_grid.data.max()]
[0.0, 10000.0]
"""
with GMTTempFile(suffix=".nc") as tmpfile:
with Session() as lib:
file_context = lib.virtualfile_from_data(check_kind="raster", data=grid)
with file_context as infile:
if (outgrid := kwargs.get("G")) is None:
kwargs["G"] = outgrid = tmpfile.name # output to tmpfile
lib.call_module(
module="grdclip", args=build_arg_string(kwargs, infile=infile)
)
return load_dataarray(outgrid) if outgrid == tmpfile.name else None