ENH: add support for passing fields keys for colors and linewidth in …

…streamline plot annotations

yt/visualization/plot_modifications.py

@@ -3,12 +3,13 @@
 import sys
 import warnings
 from abc import ABC, abstractmethod
-from functools import update_wrapper
+from functools import partial, update_wrapper
 from numbers import Integral, Number
 from typing import Any, Dict, Optional, Tuple, Type, Union
 
 import matplotlib
 import numpy as np
+from unyt import unyt_quantity
 
 from yt._maintenance.deprecation import issue_deprecation_warning
 from yt._typing import AnyFieldKey
@@ -1224,19 +1225,37 @@ class StreamlineCallback(PlotCallback):
 
     def __init__(
         self,
-        field_x,
-        field_y,
+        field_x: AnyFieldKey,
+        field_y: AnyFieldKey,
         *,
+        linewidth: Optional[Union[AnyFieldKey, float]] = None,
+        linewidth_upscaling: float = 1.0,
+        color: Optional[AnyFieldKey] = None,
         factor: Union[Tuple[int, int], int] = 16,
         density=1,
         field_color=None,
-        display_threshold=None,
+        display_threshold: Optional[Union[float, unyt_quantity]] = None,
         plot_args=None,
         **kwargs,
     ):
         self.field_x = field_x
         self.field_y = field_y
-        self.field_color = field_color
+        if color is not None and field_color is not None:
+            raise TypeError(
+                "Cannot set `color` and `field_color` keyword arguments at the same time."
+            )
+        elif field_color is not None:
+            issue_deprecation_warning(
+                "The `field_color` keyword argument is deprecated. "
+                "Use `color` instead.",
+                since="4.3",
+            )
+            self.field_color = field_color
+        else:
+            self.field_color = color
+
+        self._linewidth = linewidth
+        self._linewidth_upscaling = linewidth_upscaling
         self.factor = _validate_factor_tuple(factor)
         self.dens = density
         self.display_threshold = display_threshold
@@ -1254,44 +1273,41 @@ def __init__(
         self.plot_args = plot_args
 
     def __call__(self, plot):
-        bounds = self._physical_bounds(plot)
         xx0, xx1, yy0, yy1 = self._plot_bounds(plot)
 
         # We are feeding this size into the pixelizer, where it will properly
         # set it in reverse order
         nx = plot.raw_image_shape[1] // self.factor[0]
         ny = plot.raw_image_shape[0] // self.factor[1]
-        pixX = plot.data.ds.coordinates.pixelize(
-            plot.data.axis, plot.data, self.field_x, bounds, (nx, ny)
-        )
-        pixY = plot.data.ds.coordinates.pixelize(
-            plot.data.axis, plot.data, self.field_y, bounds, (nx, ny)
+        pixelize = partial(
+            plot.data.ds.coordinates.pixelize,
+            plot.data.axis,
+            plot.data,
+            bounds=self._physical_bounds(plot),
+            size=(nx, ny),
         )
-        if self.field_color:
-            field_colors = plot.data.ds.coordinates.pixelize(
-                plot.data.axis, plot.data, self.field_color, bounds, (nx, ny)
-            )
-
-            if self.display_threshold:
-                mask = field_colors > self.display_threshold
-                lwdefault = matplotlib.rcParams["lines.linewidth"]
+        pixX = pixelize(field=self.field_x)
+        pixY = pixelize(field=self.field_y)
+        if (
+            isinstance(self._linewidth, tuple)
+            and len(self._linewidth) == 2
+            and all(isinstance(_, str) for _ in self._linewidth)
+        ):
+            linewidth = pixelize(field=self._linewidth)
+            if plot._swap_axes:
+                linewidth = linewidth.transpose()
+        else:
+            linewidth = self._linewidth
 
-                if "linewidth" in self.plot_args:
-                    linewidth = self.plot_args["linewidth"]
-                else:
-                    linewidth = lwdefault
-
-                try:
-                    linewidth *= mask
-                    self.plot_args["linewidth"] = linewidth
-                except ValueError as e:
-                    err_msg = (
-                        "Error applying display threshold: linewidth"
-                        + "must have shape ({}, {}) or be scalar"
-                    )
-                    err_msg = err_msg.format(nx, ny)
-                    raise ValueError(err_msg) from e
+        if linewidth is not None:
+            linewidth *= self._linewidth_upscaling / np.abs(linewidth).max()
 
+        if self.field_color is not None:
+            field_colors = pixelize(field=self.field_color)
+            if plot._swap_axes:
+                field_colors = field_colors.transpose()
+            if linewidth is not None and self.display_threshold is not None:
+                linewidth *= field_colors > self.display_threshold
         else:
             field_colors = None
 
@@ -1313,6 +1329,7 @@ def __call__(self, plot):
             "v": pixY,
             "density": self.dens,
             "color": field_colors,
+            "linewidth": linewidth,
         }
         streamplot_args.update(self.plot_args)
         plot._axes.streamplot(**streamplot_args)