Added rgb_sweep generator for sweeping through colors like spectrum_c…

…olors

RELEASE.rst

@@ -1,7 +1,7 @@
 Steps to Release scikit-ued
 ===========================
 
-These are the steps to take to create a release of the module ``skued``:
+These are the steps to take to create a release of the package ``skued``:
 
 1. Switch to the release branch
 

skued/__init__.py

@@ -10,6 +10,6 @@
                      translation_rotation_matrix)
 from .array_utils import mirror, repeated_array
 from .parallel import pmap, preduce
-from .plot_utils import spectrum_colors
+from .plot_utils import spectrum_colors, rgb_sweep
 from .quantities import electron_wavelength, interaction_parameter, lorentz
 from .voigt import gaussian, lorentzian, pseudo_voigt

skued/plot_utils.py

@@ -6,6 +6,30 @@
 from collections import Iterable
 from colorsys import hsv_to_rgb
 
+def linspace(start, stop, num):
+	""" 
+	Generate linear space 
+
+    Parameters
+    ----------
+    start : float
+        The starting value of the sequence.
+    stop : float
+        The end value of the sequence.
+    num : int, optional
+        Number of samples to generate.
+	
+	Yields
+	------
+	val : float
+	"""
+	step = (stop - start)/num
+
+	val = start
+	for _ in range(num):
+		yield val
+		val += step
+
 def spectrum_colors(num_colors):
 	"""
 	Generates a set of RGB colors corresponding to the visible spectrum (i.e. the rainbow). 
@@ -35,4 +59,32 @@ def spectrum_colors(num_colors):
 
 	# Scale so that the maximum is 'purple' (hue = 0.8)
 	# otherwise plots don't look as good
-	yield from map(lambda hue: hsv_to_rgb(0.8*hue, s = 0.7, v = 0.9), hue_values)
+	yield from map(lambda hue: hsv_to_rgb(0.8*hue, s = 0.7, v = 0.9), hue_values)
+
+def rgb_sweep(num_colors, source, dest):
+	"""
+	Generate a set of RGB colors as a linear sweep between two RGB colors `source` and `dest`.
+	These colors can be used by Matplotlib, PyQtGraph, Qt, and other plotting/graphics libraries.
+
+	Parameters
+	----------
+	num_colors : int
+		Number of colors to generate.
+	source : 3-tuple of floats
+		Source color in RGB space. Values should be between 0.0 and 1.0.
+	dest : 3-tuple of floats
+		Destination color in RGB space. Values should be between 0.0 and 1.0.
+	
+	Yields
+	------
+	color : (R,G,B) tuple.
+		R, G, B values in a tuple, from 0.0 to 1.0.
+	"""	
+	red_src, grn_src, blu_src = source
+	red_dst, grn_dst, blu_dst = dest
+
+	reds = linspace(red_src, red_dst, num = num_colors)
+	greens = linspace(grn_src, grn_dst, num = num_colors)
+	blues = linspace(blu_src, blu_dst, num = num_colors)
+
+	yield from zip(reds, greens, blues)

skued/tests/test_plot_utils.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 import unittest
-from .. import spectrum_colors
+from .. import spectrum_colors, rgb_sweep
 
 class TestSpectrumColors(unittest.TestCase):
 
@@ -23,6 +23,18 @@ def test_on_length_1_iterable(self):
 		""" Test that spectrum_colors is working on single-length iterables """
 		self.assertSequenceEqual(list(spectrum_colors(1)),
 								 list(spectrum_colors([0])))
+
+class TestRGBSweep(unittest.TestCase):
 
+	def test_on_ints(self):
+		""" Test the number of elements yielded from rgb_sweep """
+		colors = rgb_sweep(10, source = (1,0,0), dest = (0,1,0))
+		self.assertEqual(len(list(colors)), 10)
+
+	def test_source_equal_to_dest(self):
+		""" Test that rgb_sweep still works if source is equal to destination."""
+		colors = rgb_sweep(10, source = (1,0,0), dest = (1,0,0))
+		self.assertEqual(len(list(colors)), 10)
+
 if __name__ == '__main__':
 	unittest.main()