diff --git a/doc/api/index.rst b/doc/api/index.rst index 8e63c016502..db7acb9aae6 100644 --- a/doc/api/index.rst +++ b/doc/api/index.rst @@ -226,6 +226,7 @@ and store them in GMT's user data directory. datasets.load_earth_mask datasets.load_earth_relief datasets.load_earth_vertical_gravity_gradient + datasets.load_mars_relief datasets.load_sample_data In addition, there is also a special function to load XYZ tile maps via diff --git a/pygmt/datasets/__init__.py b/pygmt/datasets/__init__.py index 7aba16154be..dbda07a5b32 100644 --- a/pygmt/datasets/__init__.py +++ b/pygmt/datasets/__init__.py @@ -13,5 +13,6 @@ from pygmt.datasets.earth_vertical_gravity_gradient import ( load_earth_vertical_gravity_gradient, ) +from pygmt.datasets.mars_relief import load_mars_relief from pygmt.datasets.samples import list_sample_data, load_sample_data from pygmt.datasets.tile_map import load_tile_map diff --git a/pygmt/datasets/load_remote_dataset.py b/pygmt/datasets/load_remote_dataset.py index 6f75946aea8..2ce46ae233b 100644 --- a/pygmt/datasets/load_remote_dataset.py +++ b/pygmt/datasets/load_remote_dataset.py @@ -229,6 +229,29 @@ class GMTRemoteDataset(NamedTuple): "03m": Resolution(["gridline"], True), }, ), + "mars_relief": GMTRemoteDataset( + title="Mars relief", + name="mars relief", + long_name="Mars relief", + units="meters", + extra_attributes={}, + resolutions={ + "01d": Resolution(["gridline", "pixel"], False), + "30m": Resolution(["gridline", "pixel"], False), + "20m": Resolution(["gridline", "pixel"], False), + "15m": Resolution(["gridline", "pixel"], False), + "10m": Resolution(["gridline", "pixel"], False), + "06m": Resolution(["gridline", "pixel"], False), + "05m": Resolution(["gridline", "pixel"], True), + "04m": Resolution(["gridline", "pixel"], True), + "03m": Resolution(["gridline", "pixel"], True), + "02m": Resolution(["gridline", "pixel"], True), + "01m": Resolution(["gridline", "pixel"], True), + "30s": Resolution(["gridline", "pixel"], True), + "15s": Resolution(["gridline", "pixel"], True), + "12s": Resolution(["pixel"], True), + }, + ), } diff --git a/pygmt/datasets/mars_relief.py b/pygmt/datasets/mars_relief.py new file mode 100644 index 00000000000..01111ccc871 --- /dev/null +++ b/pygmt/datasets/mars_relief.py @@ -0,0 +1,110 @@ +""" +Function to download the Mars relief dataset from the GMT data server, and load +as :class:`xarray.DataArray`. + +The grids are available in various resolutions. +""" +from typing import Literal + +from pygmt.datasets.load_remote_dataset import _load_remote_dataset +from pygmt.helpers import kwargs_to_strings + +__doctest_skip__ = ["load_mars_relief"] + + +@kwargs_to_strings(region="sequence") +def load_mars_relief( + resolution="01d", + region=None, + registration: Literal["gridline", "pixel", None] = None, +): + r""" + Load the Mars relief dataset in various resolutions. + + .. figure:: https://www.generic-mapping-tools.org/remote-datasets/_images/GMT_mars_relief.jpg + :width: 80% + :align: center + + Mars relief dataset. + + The grids are downloaded to a user data directory + (usually ``~/.gmt/server/mars/mars_relief/``) 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 + **@mars_relief**\_\ *res*\[_\ *reg*] to any grid processing function or + plotting method. *res* is the grid resolution (see below), and *reg* is the + grid registration type (**p** for pixel registration or **g** for gridline + registration). + + The default color palette table (CPT) for this dataset is + *@mars_relief.cpt*. It's implicitly used when passing in the file name of + the dataset to any grid plotting method if no CPT is explicitly specified. + When the dataset is loaded and plotted as an :class:`xarray.DataArray` + object, the default CPT is ignored, and GMT's default CPT (*turbo*) is + used. To use the dataset-specific CPT, you need to explicitly set + ``cmap="@mars_relief.cpt"``. + + Refer to :gmt-datasets:`mars-relief.html` for more details about available + datasets, including version information and references. + + 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"``, ``"15s"``, and + ``"14s"``. + 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*. + Required for grids with resolutions higher than 5 arc-minutes + (i.e., ``"05m"``). + registration + Grid registration type. Either ``"pixel"`` for pixel registration or + ``"gridline"`` for gridline registration. Default is ``None``, means + ``"gridline"`` for all resolutions except for ``"12s"`` which is + ``"pixel"`` only. + + Returns + ------- + grid : :class:`xarray.DataArray` + The Mars relief grid. Coordinates are latitude and longitude in + degrees. Relief is in meters. + + 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_mars_relief + >>> # load the default grid (gridline-registered 1 arc-degree grid) + >>> grid = load_mars_relief() + >>> # load the 30 arc-minutes grid with "gridline" registration + >>> grid = load_mars_relief(resolution="30m", registration="gridline") + >>> # load high-resolution (5 arc-minutes) grid for a specific region + >>> grid = load_mars_relief( + ... resolution="05m", + ... region=[120, 160, 30, 60], + ... registration="gridline", + ... ) + """ + grid = _load_remote_dataset( + dataset_name="mars_relief", + dataset_prefix="mars_relief_", + resolution=resolution, + region=region, + registration=registration, + ) + return grid diff --git a/pygmt/helpers/testing.py b/pygmt/helpers/testing.py index 10c10f4c6d3..2ae00fe5e0b 100644 --- a/pygmt/helpers/testing.py +++ b/pygmt/helpers/testing.py @@ -200,6 +200,9 @@ def download_test_data(): # Earth WDMAM grids "@earth_wdmam_01d_g", "@S90E000.earth_wdmam_03m_g.nc", # Specific grid for 03m test + # Mars relief grids + "@mars_relief_01d_g", + "@N00W030.mars_relief_01m_g.nc", # Specific grid for 01m test # Other cache files "@capitals.gmt", "@earth_relief_20m_holes.grd", diff --git a/pygmt/tests/test_datasets_mars_relief.py b/pygmt/tests/test_datasets_mars_relief.py new file mode 100644 index 00000000000..613fdf6c14e --- /dev/null +++ b/pygmt/tests/test_datasets_mars_relief.py @@ -0,0 +1,51 @@ +""" +Test basic functionality for loading Mars relief datasets. +""" +import numpy as np +import numpy.testing as npt +from pygmt.datasets import load_mars_relief + + +def test_mars_relief_01d(): + """ + Test some properties of the Mars relief 01d data. + """ + data = load_mars_relief(resolution="01d") + assert data.name == "mars relief" + assert data.attrs["units"] == "meters" + assert data.attrs["long_name"] == "Mars relief" + assert data.shape == (181, 361) + assert data.gmt.registration == 0 + npt.assert_allclose(data.lat, np.arange(-90, 91, 1)) + npt.assert_allclose(data.lon, np.arange(-180, 181, 1)) + npt.assert_allclose(data.min(), -7421.0, atol=0.5) + npt.assert_allclose(data.max(), 19587.5, atol=0.5) + + +def test_mars_relief_01d_with_region(): + """ + Test loading low-resolution Mars relief with 'region'. + """ + data = load_mars_relief(resolution="01d", region=[-10, 10, -5, 5]) + assert data.shape == (11, 21) + assert data.gmt.registration == 0 + npt.assert_allclose(data.lat, np.arange(-5, 6, 1)) + npt.assert_allclose(data.lon, np.arange(-10, 11, 1)) + npt.assert_allclose(data.min(), -2502.0, atol=0.5) + npt.assert_allclose(data.max(), -135.5, atol=0.5) + + +def test_mars_relief_01m_default_registration(): + """ + Test that the grid returned by default for the 1 arc-minute resolution has + a "gridline" registration. + """ + data = load_mars_relief(resolution="01m", region=[-10, -9, 3, 5]) + assert data.shape == (121, 61) + assert data.gmt.registration == 0 + assert data.coords["lat"].data.min() == 3.0 + assert data.coords["lat"].data.max() == 5.0 + assert data.coords["lon"].data.min() == -10.0 + assert data.coords["lon"].data.max() == -9.0 + npt.assert_allclose(data.min(), -3374.0, atol=0.5) + npt.assert_allclose(data.max(), -1181.0, atol=0.5)