Improved performance of colorsynth._piecewise_gaussian() using Numb…

…a. (#6)

colorsynth/_colorsynth.py

@@ -1,6 +1,8 @@
 from typing import Callable
 import pathlib
+import math
 import numpy as np
+import numba
 import astropy.units as u
 
 __all__ = [
@@ -87,15 +89,40 @@ def _piecewise_gaussian(
     mean: u.Quantity,
     stddev_1: u.Quantity,
     stddev_2: u.Quantity,
-):
-    where = x < mean
-    not_where = ~where
-    result = np.empty(x.shape)
-    result[where] = np.exp(-np.square((x[where] - mean) / stddev_1) / 2)
-    result[not_where] = np.exp(-np.square((x[not_where] - mean) / stddev_2) / 2)
+) -> np.ndarray:
+
+    unit = x.unit
+    x = x.value
+    mean = mean.to_value(unit)
+    stddev_1 = stddev_1.to_value(unit)
+    stddev_2 = stddev_2.to_value(unit)
+
+    result = _piecewise_guassian_ufunc(x, mean, stddev_1, stddev_2)
+
     return result
 
 
+@numba.vectorize(
+    [numba.float64(numba.float64, numba.float64, numba.float64, numba.float64)],
+    target="parallel",
+)
+def _piecewise_guassian_ufunc(
+    x: float,
+    mean: float,
+    stddev_1: float,
+    stddev_2: float,
+) -> float:  # pragma: nocover
+
+    if x < mean:
+        stddev = stddev_1
+    else:
+        stddev = stddev_2
+
+    a = (x - mean) / stddev
+
+    return math.exp(-a * a / 2)
+
+
 def color_matching_x(wavelength: u.Quantity) -> u.Quantity:
     r"""
     The CIE 1931 :math:`\overline{x}(\lambda)` color matching function.

pyproject.toml

@@ -15,6 +15,7 @@ classifiers = [
 ]
 dependencies = [
     "numpy",
+    "numba",
     "matplotlib",
     "astropy",
 ]