Add the Frame/Axis class for setting frame and axes [Part 1]

doc/api/index.rst

@@ -217,7 +217,9 @@ Class-style Parameters
     :toctree: generated
     :template: autosummary/params.rst
 
+    Axis
     Box
+    Frame
     Pattern
     Position
 

pygmt/params/__init__.py

@@ -3,5 +3,6 @@
 """
 
 from pygmt.params.box import Box
+from pygmt.params.frame import Axis, Frame
 from pygmt.params.pattern import Pattern
 from pygmt.params.position import Position

pygmt/params/frame.py

@@ -0,0 +1,232 @@
+"""
+The Axes, Axis, and Frame classes for specifying the frame.
+"""
+
+import dataclasses
+
+from pygmt.alias import Alias
+from pygmt.exceptions import GMTParameterError
+from pygmt.params.base import BaseParam
+
+__doctest_skip__ = ["Axis", "Frame"]
+
+
+@dataclasses.dataclass(repr=False)
+class Axis(BaseParam):
+    """
+    Class for setting up one axis of a plot.
+
+    Examples
+    --------
+    To specify the same attributes for all axes, with intervals of 4 for annotations,
+    2 for ticks, and 1 for gridlines:
+
+    >>> import pygmt
+    >>> fig = pygmt.Figure()
+    >>> fig.basemap(
+    ...     region=[0, 10, 0, 20],
+    ...     projection="X10c/10c",
+    ...     frame=Axis(annot=4, tick=2, grid=1),
+    ... )
+    >>> fig.show()
+    """
+
+    #: Specify the interval for annoations. It can be ``True`` to let GMT decide the
+    #: interval automatically; or a value to set a specific interval in the format of
+    #: *stride*\ [±\ *phase*][*unit*], where, *stride* is the interval, *phase* is the
+    #: offset to shift the annotations by that amount, and *unit* is one of the
+    #: :gmt-docs:`18 supported unit codes <reference/options.html#tbl-units>` related to
+    #: time intervals.
+    annot: float | bool = False
+
+    #: Specify the interval for ticks. Same format as ``annot``.
+    tick: float | bool = False
+
+    #: Specify the interval for gridlines. Same format as ``annot``.
+    grid: float | bool = False
+
+    #: Label for the axis [Default is no label].
+    label: str | None = None
+
+    #: A leading text prefix for the axis annotations (e.g., dollar sign for plots
+    #: related to money) [For Cartesian plots only].
+    prefix: str | None = None
+
+    #: Unit to append to the axis annotations [For Cartesian plots only].
+    unit: str | None = None
+
+    #: Angle of the axis annotations.
+    angle: float | None = None
+
+    @property
+    def _aliases(self):
+        return [
+            Alias(self.annot, name="annot", prefix="a"),
+            Alias(self.tick, name="tick", prefix="f"),
+            Alias(self.grid, name="grid", prefix="g"),
+            Alias(self.label, name="label", prefix="+l"),
+            Alias(self.angle, name="angle", prefix="+a"),
+            Alias(self.prefix, name="prefix", prefix="+p"),
+            Alias(self.unit, name="unit", prefix="+u"),
+        ]
+
+
+@dataclasses.dataclass(repr=False)
+class _Axes(BaseParam):
+    """
+    A private class to build the Axes part of the Frame class.
+    """
+
+    axes: str | None = None
+    title: str | None = None
+
+    @property
+    def _aliases(self):
+        return [
+            Alias(self.axes, name="axes"),
+            Alias(self.title, name="title", prefix="+t"),
+        ]
+
+
+@dataclasses.dataclass(repr=False)
+class Frame(BaseParam):
+    """
+    Class for setting up the frame and axes of a plot.
+
+    Examples
+    --------
+    To specify the west and south axes with both tick marks and annotations, draw the
+    east and north axes with tick marks but without annotations:
+
+    >>> import pygmt
+    >>> fig = pygmt.Figure()
+    >>> fig.basemap(
+    ...     region=[0, 10, 0, 20], projection="X10c/10c", frame=Frame(axes="WSen")
+    ... )
+    >>> fig.show()
+
+    To specify the same attributes for all axes, with intervals of 4 for annotations,
+    2 for ticks, and 1 for gridlines:
+
+    >>> fig = pygmt.Figure()
+    >>> fig.basemap(
+    ...     region=[0, 10, 0, 20],
+    ...     projection="X10c/10c",
+    ...     frame=Frame(axes="WSrt", axis=Axis(annot=4, tick=2, grid=1)),
+    ... )
+    >>> fig.show()
+
+    To specify the attributes for each axis separately:
+
+    >>> fig = pygmt.Figure()
+    >>> fig.basemap(
+    ...     region=[0, 10, 0, 20],
+    ...     projection="X10c/10c",
+    ...     frame=Frame(
+    ...         axes="WSrt",
+    ...         xaxis=Axis(annot=4, tick=2, grid=1, label="X Label"),
+    ...         yaxis=Axis(annot=5, tick=2.5, grid=1, label="Y Label"),
+    ...     ),
+    ... )
+    >>> fig.show()
+    """
+
+    #: Controls which axes are drawn and whether they are annotated, using a combination
+    #: of the codes below. Axis ommitted from the set will not be drawn.
+    #:
+    #: For a 2-D plot, there are four axes: west, east, south, and north (or left,
+    #: right, bottom, top if you prefer); For a 3-D plot, there is an extra Z-axis.
+    #: They can be denoted by the following codes:
+    #:
+    #: - **W** (west), **E** (east), **S** (south), **N** (north), **Z**: Draw axes with
+    #:   both tick marks and annotations.
+    #: - **w** (west), **e** (east), **s** (south), **n** (north), **z**: Draw axes with
+    #:   tick marks but without annotations.
+    #: - **l** (left), **r** (right), **b** (bottom), **t** (top), **u** (up): Draw axes
+    #:   without tick marks or annotations.
+    #:
+    #: For examples:
+    #:
+    #: - ``"WS"``: Draw the west and south axes with both tick marks and annotations,
+    #:   but do not draw the east and north axes.
+    #: - ``"WSen"``: Draw the west and south axes with both tick marks and annotations,
+    #:   draw the east and north axes with tick marks but without annotations.
+    #: - ``"WSrt"``: Draw the west and south axes with both tick marks and annotations,
+    #:   draw the east and north axes without tick marks or annotations.
+    #: - ``"WSrtZ"``: Draw the west and south axes with both tick marks and annotations,
+    #:   draw the east and north axes without tick marks or annotations, and draw the
+    #:   z-axis with both tick marks and annotations.
+    #:
+    #: For a 3-D plot, if the z-axis code is specified, a single vertical axis will be
+    #: drawn at the most suitable corner by default. Append any combination of the
+    #: corner IDs from 1 to 4 to draw one or more vertical axes at the corresponding
+    #: corners (e.g., ``"WSrtZ1234"``):
+    #:
+    #: - **1**: the south-western (lower-left) corner
+    #: - **2**: the south-eastern (lower-right) corner
+    #: - **3**: the north-eastern (upper-right) corner
+    #: - **4**: the north-western (upper-left) corner
+    axes: str | None = None
+
+    #: The title string centered above the plot frame [Default is no title].
+    title: str | None = None
+
+    #: Specify the attributes for axes by an :class:`Axis` object.
+    #:
+    #: The attributes for each axis can be specified in two ways: (1) specifying the
+    #: same attributes for all axes using the ``axis`` parameter; (2) specifying the
+    #: attributes for each axis separately using the ``xaxis``, ``yaxis``, ``zaxis``
+    #: parameter for the x-, y, and z-axes, respectively.
+    #:
+    #: GMT uses the notion of primary (the default) and secondary axes, while secondary
+    #: axes are optional and mostly used for time axes annotations. To specify the
+    #: attributes for the secondary axes, use the ``xaxis2``, ``yaxis2``, and ``zaxis2``
+    #: parameters.
+    axis: Axis | None = None
+    xaxis: Axis | None = None
+    yaxis: Axis | None = None
+    zaxis: Axis | None = None
+    xaxis2: Axis | None = None
+    yaxis2: Axis | None = None
+    zaxis2: Axis | None = None
+
+    def _validate(self):
+        """
+        Validate the parameters of the Frame class.
+        """
+        if self.axis is not None and any(
+            [self.xaxis, self.yaxis, self.zaxis, self.xaxis2, self.yaxis2, self.zaxis2]
+        ):
+            raise GMTParameterError(
+                conflicts_with=(
+                    "axis",
+                    ["xaxis", "yaxis", "zaxis", "xaxis2", "yaxis2", "zaxis2"],
+                ),
+                reason="Either 'axis' or the individual axis parameters can be set, but not both.",
+            )
+
+    @property
+    def _aliases(self):
+        # _Axes() maps to an empty string, which becomes '-B' without arguments and is
+        # invalid when combined with individual axis settings (e.g., '-B -Bxaf -Byaf').
+        frame_settings = _Axes(axes=self.axes, title=self.title)
+        return [
+            Alias(frame_settings) if str(frame_settings) else Alias(None),
+            Alias(self.axis, name="axis"),
+            Alias(self.xaxis, name="xaxis", prefix="px" if self.xaxis2 else "x"),
+            Alias(self.yaxis, name="yaxis", prefix="py" if self.yaxis2 else "y"),
+            Alias(self.zaxis, name="zaxis", prefix="pz" if self.zaxis2 else "z"),
+            Alias(self.xaxis2, name="xaxis2", prefix="sx"),
+            Alias(self.yaxis2, name="yaxis2", prefix="sy"),
+            Alias(self.zaxis2, name="zaxis2", prefix="sz"),
+        ]
+
+    def __iter__(self):
+        """
+        Iterate over the aliases of the class.
+
+        Yields
+        ------
+        The value of each alias in the class. None are excluded.
+        """
+        yield from (alias._value for alias in self._aliases if alias._value is not None)

pygmt/tests/test_params_frame.py

@@ -0,0 +1,95 @@
+"""
+Test the Frame and Axis classes.
+"""
+
+from pygmt.params import Axis, Frame
+
+
+def test_params_axis():
+    """
+    Test the Axis class.
+    """
+    assert str(Axis(annot=True)) == "a"
+    assert str(Axis(annot=True, tick=True, grid=True)) == "afg"
+    assert str(Axis(annot=30, tick=15, grid=5)) == "a30f15g5"
+    assert str(Axis(annot=30, label="LABEL")) == "a30+lLABEL"
+    assert str(Axis(annot=30, prefix="$", unit="m")) == "a30+p$+um"
+
+
+def test_params_frame_only():
+    """
+    Test the Frame class.
+    """
+    assert str(Frame("WSen")) == "WSen"
+    assert str(Frame(axes="WSEN", title="My Title")) == "WSEN+tMy Title"
+
+
+def test_params_frame_axis():
+    """
+    Test the Frame class with uniform axis setting.
+    """
+    frame = Frame(axes="lrtb", title="My Title", axis=Axis(annot=30, tick=15, grid=10))
+    assert list(frame) == ["lrtb+tMy Title", "a30f15g10"]
+
+    frame = Frame(
+        axes="WSEN",
+        title="My Title",
+        axis=Axis(annot=True, tick=True, grid=True, label="LABEL"),
+    )
+    assert list(frame) == ["WSEN+tMy Title", "afg+lLABEL"]
+
+
+def test_params_frame_separate_axes():
+    """
+    Test the Frame class with separate axis settings.
+    """
+    frame = Frame(
+        xaxis=Axis(annot=10, tick=5, grid=2.5),
+        yaxis=Axis(annot=20, tick=10, grid=5),
+    )
+    assert list(frame) == ["xa10f5g2.5", "ya20f10g5"]
+
+    frame = Frame(
+        axes="lrtb",
+        title="My Title",
+        xaxis=Axis(annot=10, tick=5, grid=2),
+        yaxis=Axis(annot=20, tick=10, grid=4),
+    )
+    assert list(frame) == ["lrtb+tMy Title", "xa10f5g2", "ya20f10g4"]
+
+    frame = Frame(
+        axes="WSEN",
+        title="My Title",
+        xaxis=Axis(annot=True, tick=True, grid=True, label="X-LABEL"),
+        yaxis=Axis(annot=True, tick=True, grid=True, label="Y-LABEL"),
+    )
+    assert list(frame) == ["WSEN+tMy Title", "xafg+lX-LABEL", "yafg+lY-LABEL"]
+
+
+def test_params_frame_separate_axis_secondary():
+    """
+    Test the Frame class with separate axis settings including secondary axes.
+    """
+    frame = Frame(
+        axes="lrtb",
+        title="My Title",
+        xaxis=Axis(annot=10, tick=5, grid=2),
+        xaxis2=Axis(annot=15, tick=7, grid=3),
+        yaxis=Axis(annot=20, tick=10, grid=4),
+        yaxis2=Axis(annot=25, tick=12, grid=5),
+    )
+    assert list(frame) == [
+        "lrtb+tMy Title",
+        "pxa10f5g2",
+        "pya20f10g4",
+        "sxa15f7g3",
+        "sya25f12g5",
+    ]
+
+    frame = Frame(
+        axes="WSEN",
+        title="My Title",
+        xaxis=Axis(annot=True, tick=True, grid=True, label="X-LABEL"),
+        yaxis=Axis(annot=True, tick=True, grid=True, label="Y-LABEL"),
+    )
+    assert list(frame) == ["WSEN+tMy Title", "xafg+lX-LABEL", "yafg+lY-LABEL"]