create RangeSlider widget

ianhi · ianhi · commit 8033f889adcf · 2020-10-31T11:56:51.000-04:00
diff --git a/doc/users/next_whats_new/range_slider.rst b/doc/users/next_whats_new/range_slider.rst
@@ -0,0 +1,4 @@
+New RangeSlider widget
+----------------------
+`.widgets.RangeSlider` allows for creating a slider that defines
+a range rather than a single value.
diff --git a/examples/widgets/range_slider_demo.py b/examples/widgets/range_slider_demo.py
@@ -0,0 +1,44 @@
+"""
+======================================
+Thresholding an Image with RangeSlider
+======================================
+
+Using the RangeSlider widget to control the thresholding of an image.
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+from matplotlib.widgets import RangeSlider
+
+fig, ax = plt.subplots()
+plt.subplots_adjust(left=0.25, bottom=0.25)
+np.random.seed(19680801)
+N = 128
+im = ax.imshow(np.random.rand(N * N).reshape(N, N))
+ax.margins(x=0)
+
+slider_ax = plt.axes([0.20, 0.1, 0.60, 0.03])
+slider = RangeSlider(slider_ax, "Threshold", 0.0, 1.0)
+
+
+def update(val):
+    im.norm.vmin = val[0]
+    im.norm.vmax = val[1]
+    fig.canvas.draw_idle()
+
+
+slider.on_changed(update)
+plt.show()
+
+#############################################################################
+#
+# ------------
+#
+# References
+# """"""""""
+#
+# The use of the following functions, methods, classes and modules is shown
+# in this example:
+
+import matplotlib
+matplotlib.widgets.RangeSlider
diff --git a/lib/matplotlib/tests/test_widgets.py b/lib/matplotlib/tests/test_widgets.py
@@ -287,6 +287,22 @@ def test_slider_horizontal_vertical():
     assert_allclose(box.bounds, [0, 0, 1, 10/24])
 
 
+def test_range_slider():
+    fig, ax = plt.subplots()
+    plt.subplots_adjust(left=0.25, bottom=0.25)
+
+    slider = widgets.RangeSlider(ax=ax, label='', valmin=0., valmax=1.)
+
+    slider.set_val((.2, .6))
+    assert_allclose(slider.val, (.2, .6))
+
+    slider.set_val((.2, .1))
+    assert_allclose(slider.val, (.1, .2))
+
+    slider.set_val((-1, 10))
+    assert_allclose(slider.val, (0, 1))
+
+
 def check_polygon_selector(event_sequence, expected_result, selections_count):
     """
     Helper function to test Polygon Selector.
diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
