Source code for pygmt.datasets.tile_map

Function to load raster tile maps from XYZ tile providers, and load as

from typing import Literal

from packaging.version import Version

    import contextily
    from xyzservices import TileProvider

except ImportError:
    TileProvider = None

import numpy as np
import xarray as xr

__doctest_requires__ = {("load_tile_map"): ["contextily"]}

[docs] def load_tile_map( region: list, zoom: int | Literal["auto"] = "auto", source: TileProvider | str | None = None, lonlat: bool = True, wait: int = 0, max_retries: int = 2, zoom_adjust: int | None = None, ) -> xr.DataArray: """ Load a georeferenced raster tile map from XYZ tile providers. The tiles that compose the map are merged and georeferenced into an :class:`xarray.DataArray` image with 3 bands (RGB). Note that the returned image is in a Spherical Mercator (EPSG:3857) coordinate reference system. Parameters ---------- region The bounding box of the map in the form of a list [*xmin*, *xmax*, *ymin*, *ymax*]. These coordinates should be in longitude/latitude if ``lonlat=True`` or Spherical Mercator (EPSG:3857) if ``lonlat=False``. zoom Level of detail. Higher levels (e.g. ``22``) mean a zoom level closer to the Earth's surface, with more tiles covering a smaller geographical area and thus more detail. Lower levels (e.g. ``0``) mean a zoom level further from the Earth's surface, with less tiles covering a larger geographical area and thus less detail. Default is ``"auto"`` to automatically determine the zoom level based on the bounding box region extent. .. note:: The maximum possible zoom level may be smaller than ``22``, and depends on what is supported by the chosen web tile provider source. source The tile source: web tile provider or path to a local file. Provide either: - A web tile provider in the form of a :class:`xyzservices.TileProvider` object. See :doc:`Contextily providers <contextily:providers_deepdive>` for a list of tile providers. Default is ``xyzservices.providers.OpenStreetMap.HOT``, i.e. OpenStreetMap Humanitarian web tiles. - A web tile provider in the form of a URL. The placeholders for the XYZ in the URL need to be {x}, {y}, {z}, respectively. E.g. ``https://{s}{z}/{x}/{y}.png``. - A local file path. The file is read with :doc:`rasterio <rasterio:index>` and all bands are loaded into the basemap. See :doc:`contextily:working_with_local_files`. .. important:: Tiles are assumed to be in the Spherical Mercator projection (EPSG:3857). lonlat If ``False``, coordinates in ``region`` are assumed to be Spherical Mercator as opposed to longitude/latitude. wait If the tile API is rate-limited, the number of seconds to wait between a failed request and the next try. max_retries Total number of rejected requests allowed before contextily will stop trying to fetch more tiles from a rate-limited API. zoom_adjust The amount to adjust a chosen zoom level if it is chosen automatically. Values outside of -1 to 1 are not recommended as they can lead to slow execution. .. note:: The ``zoom_adjust`` parameter requires ``contextily>=1.5.0``. Returns ------- raster Georeferenced 3-D data array of RGB values. Raises ------ ImportError If ``contextily`` is not installed or can't be imported. Follow the :doc:`install instructions for contextily <contextily:index>`, (e.g. via ``python -m pip install contextily``) before using this function. Examples -------- >>> import contextily >>> from pygmt.datasets import load_tile_map >>> raster = load_tile_map( ... region=[-180.0, 180.0, -90.0, 0.0], # West, East, South, North ... zoom=1, # less detailed zoom level ... source=contextily.providers.OpenTopoMap, ... lonlat=True, # bounding box coordinates are longitude/latitude ... ) >>> raster.sizes Frozen({'band': 3, 'y': 256, 'x': 512}) >>> raster.coords # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE Coordinates: * band (band) uint8 ... 0 1 2 * y (y) float64 ... -7.081e-10 -7.858e+04 ... -1.996e+07 ... * x (x) float64 ... -2.004e+07 -1.996e+07 ... 1.996e+07 2.004e+07 """ if not _HAS_CONTEXTILY: raise ImportError( "Package `contextily` is required to be installed to use this function. " "Please use `python -m pip install contextily` or " "`mamba install -c conda-forge contextily` " "to install the package." ) contextily_kwargs = {} if zoom_adjust is not None: contextily_kwargs["zoom_adjust"] = zoom_adjust if Version(contextily.__version__) < Version("1.5.0"): raise TypeError( "The `zoom_adjust` parameter requires `contextily>=1.5.0` to work. " "Please upgrade contextily, or manually set the `zoom` level instead." ) west, east, south, north = region image, extent = contextily.bounds2img( w=west, s=south, e=east, n=north, zoom=zoom, source=source, ll=lonlat, wait=wait, max_retries=max_retries, **contextily_kwargs, ) # Turn RGBA img from channel-last to channel-first and get 3-band RGB only _image = image.transpose(2, 0, 1) # Change image from (H, W, C) to (C, H, W) rgb_image = _image[0:3, :, :] # Get just RGB by dropping RGBA's alpha channel # Georeference RGB image into an xarray.DataArray left, right, bottom, top = extent dataarray = xr.DataArray( data=rgb_image, coords={ "band": np.array(object=[0, 1, 2], dtype=np.uint8), # Red, Green, Blue "y": np.linspace(start=top, stop=bottom, num=rgb_image.shape[1]), "x": np.linspace(start=left, stop=right, num=rgb_image.shape[2]), }, dims=("band", "y", "x"), ) # If rioxarray is installed, set the coordinate reference system if hasattr(dataarray, "rio"): dataarray ="EPSG:3857") return dataarray