Figure.coast/pygmt.select/pygmt.grdlandmask: Use long names ("crude"/"low"/"intermediate"/"high"/"full") for the 'resolution' parameter

examples/tutorials/basics/coastlines.py

@@ -27,9 +27,9 @@
 # 3. island-in-lake shore
 # 4. lake-in-island-in-lake shore
 #
-# You can specify which level you want to plot by passing the level number and
-# a GMT pen configuration. For example, to plot just the coastlines with 0.5p
-# thickness and black lines:
+# You can specify which level you want to plot by passing the level number and a GMT
+# pen configuration. For example, to plot just the coastlines with 0.5p thickness and
+# black lines:
 
 fig = pygmt.Figure()
 fig.basemap(region="g", projection="W15c", frame=True)
@@ -50,18 +50,14 @@
 # Resolutions
 # -----------
 #
-# The coastline database comes with 5 resolutions. The resolution drops by 80%
-# between levels:
-#
-# 1. ``"c"``: crude
-# 2. ``"l"``: low (default)
-# 3. ``"i"``: intermediate
-# 4. ``"h"``: high
-# 5. ``"f"``: full
+# The coastline database comes with 5 resolutions: ``"full"``, ``"high"``,
+# ``"intermediate"``, ``"low"``, and ``"crude"``. The resolution drops by 80% between
+# levels. The ``resolution`` parameter defaults to ``"auto"`` to automatically select
+# the best resolution given the chosen map scale.
 
 oahu = [-158.3, -157.6, 21.2, 21.8]
 fig = pygmt.Figure()
-for res in ["c", "l", "i", "h", "f"]:
+for res in ["crude", "low", "intermediate", "high", "full"]:
     fig.coast(resolution=res, shorelines="1p", region=oahu, projection="M5c")
     fig.shift_origin(xshift="5c")
 fig.show()
@@ -71,9 +67,9 @@
 # Land and water
 # --------------
 #
-# Use the ``land`` and ``water`` parameters to specify a fill color for land
-# and water bodies. The colors can be given by name or hex codes (like the ones
-# used in HTML and CSS):
+# Use the ``land`` and ``water`` parameters to specify a fill color for land and water
+# bodies. The colors can be given by name or hex codes (like the ones used in HTML and
+# CSS):
 
 fig = pygmt.Figure()
 fig.basemap(region="g", projection="W15c", frame=True)

pygmt/src/_common.py

@@ -251,3 +251,56 @@ def from_params(
             f"{', '.join(params)}."
         )
         raise GMTInvalidInput(msg)
+
+
+def _parse_coastline_resolution(
+    resolution: Literal["auto", "full", "high", "intermediate", "low", "crude", None],
+) -> Literal["a", "f", "h", "i", "l", "c", None]:
+    """
+    Parse the 'resolution' parameter for coastline-related functions.
+
+    Parameters
+    ----------
+    resolution
+        The resolution of the coastline dataset to use. The available resolutions from
+        highest to lowest are: ``"full"``, ``"high"``, ``"intermediate"``, ``"low"``,
+        and ``"crude"``, which drops by 80% between levels. Alternatively, choose
+        ``"auto"`` to automatically select the most suitable resolution given the chosen
+        map scale or region. ``None`` means using the default resolution.
+
+    Returns
+    -------
+    The single-letter resolution code or ``None``.
+
+    Raises
+    ------
+    GMTInvalidInput
+        If the resolution is invalid.
+
+    Examples
+    --------
+    >>> _parse_coastline_resolution("full")
+    'f'
+    >>> _parse_coastline_resolution("f")
+    'f'
+    >>> _parse_coastline_resolution(None)
+    >>> _parse_coastline_resolution("invalid")
+    Traceback (most recent call last):
+    ...
+    pygmt.exceptions.GMTInvalidInput: Invalid resolution: 'invalid'. Valid values ...
+    """
+    if resolution is None:
+        return None
+
+    _valid_res = {"auto", "full", "high", "intermediate", "low", "crude"}
+
+    if resolution in _valid_res:  # Long-form arguments.
+        return resolution[0]  # type: ignore[return-value]
+
+    if resolution in {_res[0] for _res in _valid_res}:  # Short-form arguments.
+        return resolution  # type: ignore[return-value]
+
+    msg = (
+        f"Invalid resolution: '{resolution}'. Valid values are {', '.join(_valid_res)}."
+    )
+    raise GMTInvalidInput(msg)

pygmt/src/coast.py

@@ -2,6 +2,8 @@
 coast - Plot continents, countries, shorelines, rivers, and borders.
 """
 
+from typing import Literal
+
 from pygmt.clib import Session
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import (
@@ -11,6 +13,7 @@
     kwargs_to_strings,
     use_alias,
 )
+from pygmt.src._common import _parse_coastline_resolution
 
 __doctest_skip__ = ["coast"]
 
@@ -20,7 +23,6 @@
     A="area_thresh",
     B="frame",
     C="lakes",
-    D="resolution",
     E="dcw",
     F="box",
     G="land",
@@ -37,7 +39,13 @@
     t="transparency",
 )
 @kwargs_to_strings(R="sequence", c="sequence_comma", p="sequence")
-def coast(self, **kwargs):
+def coast(
+    self,
+    resolution: Literal[
+        "auto", "full", "high", "intermediate", "low", "crude", None
+    ] = None,
+    **kwargs,
+):
     r"""
     Plot continents, countries, shorelines, rivers, and borders.
 
@@ -73,10 +81,12 @@ def coast(self, **kwargs):
         parameter. Optionally, specify separate fills by appending
         **+l** for lakes or **+r** for river-lakes, and passing multiple
         strings in a list.
-    resolution : str
-        **f**\|\ **h**\|\ **i**\|\ **l**\|\ **c**.
-        Select the resolution of the data set to: (**f**\ )ull, (**h**\ )igh,
-        (**i**\ )ntermediate, (**l**\ )ow, and (**c**\ )rude.
+    resolution
+        Select the resolution of the coastline dataset to use. The available resolutions
+        from highest to lowest are: ``"full"``, ``"high"``, ``"intermediate"``,
+        ``"low"``, and ``"crude"``, which drops by 80% between levels. Default is
+        ``"auto"`` to automatically select the most suitable resolution given the chosen
+        map scale.
     land : str
         Select filling of "dry" areas.
     rivers : int, str, or list
@@ -200,5 +210,8 @@ def coast(self, **kwargs):
             "lakes, land, water, rivers, borders, dcw, Q, or shorelines."
         )
         raise GMTInvalidInput(msg)
+
+    kwargs["D"] = kwargs.get("D", _parse_coastline_resolution(resolution))
+
     with Session() as lib:
         lib.call_module(module="coast", args=build_arg_list(kwargs))

pygmt/src/grdlandmask.py

@@ -2,19 +2,21 @@
 grdlandmask - Create a "wet-dry" mask grid from shoreline database.
 """
 
+from typing import Literal
+
 import xarray as xr
 from pygmt._typing import PathLike
 from pygmt.clib import Session
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import build_arg_list, fmt_docstring, kwargs_to_strings, use_alias
+from pygmt.src._common import _parse_coastline_resolution
 
 __doctest_skip__ = ["grdlandmask"]
 
 
 @fmt_docstring
 @use_alias(
     A="area_thresh",
-    D="resolution",
     E="bordervalues",
     I="spacing",
     N="maskvalues",
@@ -24,7 +26,13 @@
     x="cores",
 )
 @kwargs_to_strings(I="sequence", R="sequence", N="sequence", E="sequence")
-def grdlandmask(outgrid: PathLike | None = None, **kwargs) -> xr.DataArray | None:
+def grdlandmask(
+    outgrid: PathLike | None = None,
+    resolution: Literal[
+        "auto", "full", "high", "intermediate", "low", "crude", None
+    ] = None,
+    **kwargs,
+) -> xr.DataArray | None:
     r"""
     Create a "wet-dry" mask grid from shoreline database.
 
@@ -44,17 +52,15 @@ def grdlandmask(outgrid: PathLike | None = None, **kwargs) -> xr.DataArray | Non
     {spacing}
     {region}
     {area_thresh}
-    resolution : str
-        *res*\[\ **+f**\]. Select the resolution of the data set to use
-        ((**f**)ull, (**h**)igh, (**i**)ntermediate, (**l**)ow, or
-        (**c**)rude). The resolution drops off by ~80% between data sets.
-        [Default is **l**]. Append **+f** to automatically select a lower
-        resolution should the one requested not be available
-        [abort if not found]. Alternatively, choose (**a**)uto to automatically
-        select the best resolution given the chosen region. Note that because
-        the coastlines differ in details a node in a mask file using one
-        resolution is not guaranteed to remain inside [or outside] when a
-        different resolution is selected.
+    resolution
+        Select the resolution of the coastline dataset to use. The available resolutions
+        from highest to lowest are: ``"full"``, ``"high"``, ``"intermediate"``,
+        ``"low"``, and ``"crude"``, which drops by 80% between levels. Alternatively,
+        choose ``"auto"`` to automatically select the most suitable resolution given the
+        chosen region. Note that because the coastlines differ in details, a node in a
+        mask file using one resolution is not guaranteed to remain inside [or outside]
+        when a different resolution is selected. If ``None``, the low resolution is used
+        by default.
     maskvalues : list
         Set the values that will be assigned to nodes, in the form of [*wet*, *dry*], or
         [*ocean*, *land*, *lake*, *island*, *pond*]. Default is ``[0, 1, 0, 1, 0]``
@@ -102,6 +108,8 @@ def grdlandmask(outgrid: PathLike | None = None, **kwargs) -> xr.DataArray | Non
         msg = "Both 'region' and 'spacing' must be specified."
         raise GMTInvalidInput(msg)
 
+    kwargs["D"] = kwargs.get("D", _parse_coastline_resolution(resolution))
+
     with Session() as lib:
         with lib.virtualfile_out(kind="grid", fname=outgrid) as voutgrd:
             kwargs["G"] = voutgrd

pygmt/src/select.py

@@ -15,6 +15,7 @@
     use_alias,
     validate_output_table_type,
 )
+from pygmt.src._common import _parse_coastline_resolution
 
 __doctest_skip__ = ["select"]
 
@@ -23,7 +24,6 @@
 @use_alias(
     A="area_thresh",
     C="dist2pt",
-    D="resolution",
     F="polygon",
     G="gridmask",
     I="reverse",
@@ -49,6 +49,9 @@ def select(
     data: PathLike | TableLike | None = None,
     output_type: Literal["pandas", "numpy", "file"] = "pandas",
     outfile: PathLike | None = None,
+    resolution: Literal[
+        "auto", "full", "high", "intermediate", "low", "crude", None
+    ] = None,
     **kwargs,
 ) -> pd.DataFrame | np.ndarray | None:
     r"""
@@ -117,16 +120,6 @@ def select(
         <reference/file-formats.html#optional-segment-header-records>`
         *polygonfile*. For spherical polygons (lon, lat), make sure no
         consecutive points are separated by 180 degrees or more in longitude.
-    resolution : str
-        *resolution*\ [**+f**].
-        Ignored unless ``mask`` is set. Selects the resolution of the coastline
-        data set to use ((**f**)ull, (**h**)igh, (**i**)ntermediate, (**l**)ow,
-        or (**c**)rude). The resolution drops off by ~80% between data sets.
-        [Default is **l**]. Append (**+f**) to automatically select a lower
-        resolution should the one requested not be available [Default is abort
-        if not found]. Note that because the coastlines differ in details
-        it is not guaranteed that a point will remain inside [or outside] when
-        a different resolution is selected.
     gridmask : str
         Pass all locations that are inside the valid data area of the grid
         *gridmask*. Nodes that are outside are either NaN or zero.
@@ -155,6 +148,15 @@ def select(
 
         [Default is s/k/s/k/s (i.e., s/k), which passes all points on dry
         land].
+    resolution
+        Ignored unless ``mask`` is set. Select the resolution of the coastline dataset
+        to use. The available resolutions from highest to lowest are: ``"full"``,
+        ``"high"``, ``"intermediate"``, ``"low"``, and ``"crude"``, which drops by 80%
+        between levels. Alternatively, choose ``"auto"`` to automatically select the
+        most suitable resolution given the chosen region. Note that because the
+        coastlines differ in details, a node in a mask file using one resolution is not
+        guaranteed to remain inside [or outside] when a different resolution is
+        selected. If ``None``, the low resolution is used by default.
     {region}
     {verbose}
     z_subregion : str or list
@@ -206,6 +208,8 @@ def select(
     >>> # longitudes 246 and 247 and latitudes 20 and 21
     >>> out = pygmt.select(data=ship_data, region=[246, 247, 20, 21])
     """
+    kwargs["D"] = kwargs.get("D", _parse_coastline_resolution(resolution))
+
     output_type = validate_output_table_type(output_type, outfile=outfile)
 
     column_names = None

pygmt/tests/test_coast.py

@@ -29,7 +29,7 @@ def test_coast_world_mercator():
         projection="M15c",
         frame="af",
         land="#aaaaaa",
-        resolution="c",
+        resolution="crude",
         water="white",
     )
     return fig