327 lines
12 KiB
Python
327 lines
12 KiB
Python
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import numpy as np
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from matplotlib import ticker as mticker, _api
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from matplotlib.transforms import Bbox, Transform
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def _find_line_box_crossings(xys, bbox):
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"""
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Find the points where a polyline crosses a bbox, and the crossing angles.
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Parameters
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----------
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xys : (N, 2) array
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The polyline coordinates.
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bbox : `.Bbox`
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The bounding box.
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Returns
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-------
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list of ((float, float), float)
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Four separate lists of crossings, for the left, right, bottom, and top
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sides of the bbox, respectively. For each list, the entries are the
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``((x, y), ccw_angle_in_degrees)`` of the crossing, where an angle of 0
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means that the polyline is moving to the right at the crossing point.
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The entries are computed by linearly interpolating at each crossing
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between the nearest points on either side of the bbox edges.
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"""
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crossings = []
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dxys = xys[1:] - xys[:-1]
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for sl in [slice(None), slice(None, None, -1)]:
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us, vs = xys.T[sl] # "this" coord, "other" coord
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dus, dvs = dxys.T[sl]
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umin, vmin = bbox.min[sl]
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umax, vmax = bbox.max[sl]
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for u0, inside in [(umin, us > umin), (umax, us < umax)]:
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cross = []
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idxs, = (inside[:-1] ^ inside[1:]).nonzero()
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for idx in idxs:
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v = vs[idx] + (u0 - us[idx]) * dvs[idx] / dus[idx]
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if not vmin <= v <= vmax:
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continue
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crossing = (u0, v)[sl]
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theta = np.degrees(np.arctan2(*dxys[idx][::-1]))
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cross.append((crossing, theta))
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crossings.append(cross)
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return crossings
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class ExtremeFinderSimple:
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"""
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A helper class to figure out the range of grid lines that need to be drawn.
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"""
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def __init__(self, nx, ny):
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"""
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Parameters
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----------
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nx, ny : int
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The number of samples in each direction.
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"""
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self.nx = nx
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self.ny = ny
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def __call__(self, transform_xy, x1, y1, x2, y2):
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"""
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Compute an approximation of the bounding box obtained by applying
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*transform_xy* to the box delimited by ``(x1, y1, x2, y2)``.
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The intended use is to have ``(x1, y1, x2, y2)`` in axes coordinates,
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and have *transform_xy* be the transform from axes coordinates to data
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coordinates; this method then returns the range of data coordinates
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that span the actual axes.
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The computation is done by sampling ``nx * ny`` equispaced points in
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the ``(x1, y1, x2, y2)`` box and finding the resulting points with
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extremal coordinates; then adding some padding to take into account the
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finite sampling.
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As each sampling step covers a relative range of *1/nx* or *1/ny*,
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the padding is computed by expanding the span covered by the extremal
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coordinates by these fractions.
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"""
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x, y = np.meshgrid(
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np.linspace(x1, x2, self.nx), np.linspace(y1, y2, self.ny))
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xt, yt = transform_xy(np.ravel(x), np.ravel(y))
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return self._add_pad(xt.min(), xt.max(), yt.min(), yt.max())
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def _add_pad(self, x_min, x_max, y_min, y_max):
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"""Perform the padding mentioned in `__call__`."""
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dx = (x_max - x_min) / self.nx
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dy = (y_max - y_min) / self.ny
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return x_min - dx, x_max + dx, y_min - dy, y_max + dy
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class _User2DTransform(Transform):
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"""A transform defined by two user-set functions."""
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input_dims = output_dims = 2
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def __init__(self, forward, backward):
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"""
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Parameters
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----------
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forward, backward : callable
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The forward and backward transforms, taking ``x`` and ``y`` as
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separate arguments and returning ``(tr_x, tr_y)``.
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"""
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# The normal Matplotlib convention would be to take and return an
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# (N, 2) array but axisartist uses the transposed version.
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super().__init__()
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self._forward = forward
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self._backward = backward
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def transform_non_affine(self, values):
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# docstring inherited
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return np.transpose(self._forward(*np.transpose(values)))
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def inverted(self):
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# docstring inherited
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return type(self)(self._backward, self._forward)
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class GridFinder:
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"""
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Internal helper for `~.grid_helper_curvelinear.GridHelperCurveLinear`, with
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the same constructor parameters; should not be directly instantiated.
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"""
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def __init__(self,
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transform,
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extreme_finder=None,
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grid_locator1=None,
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grid_locator2=None,
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tick_formatter1=None,
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tick_formatter2=None):
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if extreme_finder is None:
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extreme_finder = ExtremeFinderSimple(20, 20)
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if grid_locator1 is None:
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grid_locator1 = MaxNLocator()
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if grid_locator2 is None:
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grid_locator2 = MaxNLocator()
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if tick_formatter1 is None:
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tick_formatter1 = FormatterPrettyPrint()
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if tick_formatter2 is None:
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tick_formatter2 = FormatterPrettyPrint()
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self.extreme_finder = extreme_finder
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self.grid_locator1 = grid_locator1
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self.grid_locator2 = grid_locator2
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self.tick_formatter1 = tick_formatter1
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self.tick_formatter2 = tick_formatter2
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self.set_transform(transform)
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def _format_ticks(self, idx, direction, factor, levels):
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"""
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Helper to support both standard formatters (inheriting from
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`.mticker.Formatter`) and axisartist-specific ones; should be called instead of
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directly calling ``self.tick_formatter1`` and ``self.tick_formatter2``. This
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method should be considered as a temporary workaround which will be removed in
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the future at the same time as axisartist-specific formatters.
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"""
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fmt = _api.check_getitem(
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{1: self.tick_formatter1, 2: self.tick_formatter2}, idx=idx)
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return (fmt.format_ticks(levels) if isinstance(fmt, mticker.Formatter)
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else fmt(direction, factor, levels))
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def get_grid_info(self, x1, y1, x2, y2):
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"""
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lon_values, lat_values : list of grid values. if integer is given,
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rough number of grids in each direction.
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"""
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extremes = self.extreme_finder(self.inv_transform_xy, x1, y1, x2, y2)
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# min & max rage of lat (or lon) for each grid line will be drawn.
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# i.e., gridline of lon=0 will be drawn from lat_min to lat_max.
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lon_min, lon_max, lat_min, lat_max = extremes
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lon_levs, lon_n, lon_factor = self.grid_locator1(lon_min, lon_max)
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lon_levs = np.asarray(lon_levs)
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lat_levs, lat_n, lat_factor = self.grid_locator2(lat_min, lat_max)
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lat_levs = np.asarray(lat_levs)
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lon_values = lon_levs[:lon_n] / lon_factor
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lat_values = lat_levs[:lat_n] / lat_factor
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lon_lines, lat_lines = self._get_raw_grid_lines(lon_values,
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lat_values,
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lon_min, lon_max,
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lat_min, lat_max)
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bb = Bbox.from_extents(x1, y1, x2, y2).expanded(1 + 2e-10, 1 + 2e-10)
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grid_info = {
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"extremes": extremes,
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# "lon", "lat", filled below.
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}
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for idx, lon_or_lat, levs, factor, values, lines in [
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(1, "lon", lon_levs, lon_factor, lon_values, lon_lines),
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(2, "lat", lat_levs, lat_factor, lat_values, lat_lines),
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]:
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grid_info[lon_or_lat] = gi = {
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"lines": [[l] for l in lines],
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"ticks": {"left": [], "right": [], "bottom": [], "top": []},
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}
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for (lx, ly), v, level in zip(lines, values, levs):
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all_crossings = _find_line_box_crossings(np.column_stack([lx, ly]), bb)
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for side, crossings in zip(
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["left", "right", "bottom", "top"], all_crossings):
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for crossing in crossings:
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gi["ticks"][side].append({"level": level, "loc": crossing})
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for side in gi["ticks"]:
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levs = [tick["level"] for tick in gi["ticks"][side]]
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labels = self._format_ticks(idx, side, factor, levs)
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for tick, label in zip(gi["ticks"][side], labels):
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tick["label"] = label
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return grid_info
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def _get_raw_grid_lines(self,
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lon_values, lat_values,
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lon_min, lon_max, lat_min, lat_max):
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lons_i = np.linspace(lon_min, lon_max, 100) # for interpolation
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lats_i = np.linspace(lat_min, lat_max, 100)
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lon_lines = [self.transform_xy(np.full_like(lats_i, lon), lats_i)
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for lon in lon_values]
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lat_lines = [self.transform_xy(lons_i, np.full_like(lons_i, lat))
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for lat in lat_values]
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return lon_lines, lat_lines
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def set_transform(self, aux_trans):
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if isinstance(aux_trans, Transform):
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self._aux_transform = aux_trans
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elif len(aux_trans) == 2 and all(map(callable, aux_trans)):
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self._aux_transform = _User2DTransform(*aux_trans)
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else:
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raise TypeError("'aux_trans' must be either a Transform "
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"instance or a pair of callables")
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def get_transform(self):
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return self._aux_transform
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update_transform = set_transform # backcompat alias.
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def transform_xy(self, x, y):
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return self._aux_transform.transform(np.column_stack([x, y])).T
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def inv_transform_xy(self, x, y):
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return self._aux_transform.inverted().transform(
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np.column_stack([x, y])).T
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def update(self, **kwargs):
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for k, v in kwargs.items():
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if k in ["extreme_finder",
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"grid_locator1",
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"grid_locator2",
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"tick_formatter1",
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"tick_formatter2"]:
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setattr(self, k, v)
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else:
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raise ValueError(f"Unknown update property {k!r}")
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class MaxNLocator(mticker.MaxNLocator):
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def __init__(self, nbins=10, steps=None,
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trim=True,
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integer=False,
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symmetric=False,
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prune=None):
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# trim argument has no effect. It has been left for API compatibility
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super().__init__(nbins, steps=steps, integer=integer,
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symmetric=symmetric, prune=prune)
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self.create_dummy_axis()
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def __call__(self, v1, v2):
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locs = super().tick_values(v1, v2)
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return np.array(locs), len(locs), 1 # 1: factor (see angle_helper)
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class FixedLocator:
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def __init__(self, locs):
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self._locs = locs
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def __call__(self, v1, v2):
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v1, v2 = sorted([v1, v2])
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locs = np.array([l for l in self._locs if v1 <= l <= v2])
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return locs, len(locs), 1 # 1: factor (see angle_helper)
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# Tick Formatter
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class FormatterPrettyPrint:
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def __init__(self, useMathText=True):
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self._fmt = mticker.ScalarFormatter(
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useMathText=useMathText, useOffset=False)
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self._fmt.create_dummy_axis()
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def __call__(self, direction, factor, values):
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return self._fmt.format_ticks(values)
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class DictFormatter:
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def __init__(self, format_dict, formatter=None):
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"""
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format_dict : dictionary for format strings to be used.
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formatter : fall-back formatter
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"""
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super().__init__()
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self._format_dict = format_dict
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self._fallback_formatter = formatter
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def __call__(self, direction, factor, values):
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"""
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factor is ignored if value is found in the dictionary
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"""
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if self._fallback_formatter:
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fallback_strings = self._fallback_formatter(
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direction, factor, values)
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else:
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fallback_strings = [""] * len(values)
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return [self._format_dict.get(k, v)
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for k, v in zip(values, fallback_strings)]
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