Source code for pygmt.datasets.earth_mask

Function to download the GSHHG Global Earth Mask from the GMT data server, and
load as :class:`xarray.DataArray`.

The grids are available in various resolutions.
from pygmt.datasets.load_remote_dataset import _load_remote_dataset
from pygmt.helpers import kwargs_to_strings

__doctest_skip__ = ["load_earth_mask"]

[docs]@kwargs_to_strings(region="sequence") def load_earth_mask(resolution="01d", region=None, registration=None): r""" Load the GSHHG Global Earth Mask in various resolutions. The grids are downloaded to a user data directory (usually ``~/.gmt/server/earth/earth_mask/``) the first time you invoke this function. Afterwards, it will load the grid from the data directory. So you'll need an internet connection the first time around. These grids can also be accessed by passing in the file name **@earth_mask**\_\ *res*\[_\ *reg*] to any grid plotting/processing function. *res* is the grid resolution (see below), and *reg* is grid registration type (**p** for pixel registration or **g** for gridline registration). Refer to :gmt-datasets:`earth-mask.html` for more details. Parameters ---------- resolution : str The grid resolution. The suffix ``d``, ``m``, and ``s`` stand for arc-degrees, arc-minutes, and arc-seconds. It can be ``"01d"``, ``"30m"``, ``"20m"``, ``"15m"``, ``"10m"``, ``"06m"``, ``"05m"``, ``"04m"``, ``"03m"``, ``"02m"``, ``"01m"``, ``"30s"``, or ``"15s"``. region : str or list The subregion of the grid to load, in the form of a list [*xmin*, *xmax*, *ymin*, *ymax*] or a string *xmin/xmax/ymin/ymax*. registration : str Grid registration type. Either ``"pixel"`` for pixel registration or ``"gridline"`` for gridline registration. Default is ``"gridline"``. Returns ------- grid : :class:`xarray.DataArray` The Earth mask grid. Coordinates are latitude and longitude in degrees. The node values in the mask grids are all in the 0-4 range and reflect different surface types: - 0: Oceanic areas beyond the shoreline - 1: Land areas inside the shoreline - 2: Lakes inside the land areas - 3: Islands in lakes in the land areas - 4: Smaller lakes in islands that are found within lakes inside the land area Note ---- The registration and coordinate system type of the returned :class:`xarray.DataArray` grid can be accessed via the GMT accessors (i.e., ``grid.gmt.registration`` and ``grid.gmt.gtype`` respectively). However, these properties may be lost after specific grid operations (such as slicing) and will need to be manually set before passing the grid to any PyGMT data processing or plotting functions. Refer to :class:`pygmt.GMTDataArrayAccessor` for detailed explanations and workarounds. Examples -------- >>> from pygmt.datasets import load_earth_mask >>> # load the default grid (gridline-registered 1 arc-degree grid) >>> grid = load_earth_mask() >>> # location (120°E, 50°N) is in land area (1) >>> grid.sel(lon=120, lat=50).values array(1, dtype=int8) >>> # location (170°E, 50°N) is in oceanic area (0) >>> grid.sel(lon=170, lat=50).values array(0, dtype=int8) """ grid = _load_remote_dataset( dataset_name="earth_mask", dataset_prefix="earth_mask_", resolution=resolution, region=region, registration=registration, ) # `return grid.astype("int8")` doesn't work because grid encoding is lost. # See ="int8") return grid