33Interactive Adjustment of Colormap Range
44========================================
55
6- Demonstration of using colorbarpicker functionality to make an
6+ Demonstration of using colorbar, picker, andevent functionality to make an
77interactively adjustable colorbar widget.
8+
9+ Left clicks and drags inside the colorbar axes adjust the high range of the
10+ color scheme. Likewise, right clicks and drags adjust the low range. The
11+ connected AxesImage immediately updates to reflect the change.
812"""
913
1014import numpy as np
1115import matplotlib .pyplot as plt
1216from matplotlib .backend_bases import MouseButton
1317
1418
15- def pick_fn (event ):
19+ def on_pick (event ):
1620adjust_colorbar (event .mouseevent )
1721
1822
19- def motion_fn (mouseevent ):
20- if mouseevent .inaxes is colorbar .ax . axes :
23+ def on_move (mouseevent ):
24+ if mouseevent .inaxes is colorbar .ax :
2125adjust_colorbar (mouseevent )
2226
2327
@@ -35,18 +39,29 @@ def adjust_colorbar(mouseevent):
3539
3640fig ,ax = plt .subplots ()
3741canvas = fig .canvas
38- arr = np .random .random ((100 ,100 ))
39- axesimage = plt .imshow (arr )
42+
43+ delta = 0.1
44+ x = np .arange (- 3.0 ,4.001 ,delta )
45+ y = np .arange (- 4.0 ,3.001 ,delta )
46+ X ,Y = np .meshgrid (x ,y )
47+ Z1 = np .exp (- X ** 2 - Y ** 2 )
48+ Z2 = np .exp (- (X - 1 )** 2 - (Y - 1 )** 2 )
49+ Z = (0.9 * Z1 - 0.5 * Z2 )* 2
50+
51+ cmap = plt .get_cmap ('viridis' ).with_extremes (over = 'xkcd:orange' ,under = 'xkcd:dark red' )
52+ axesimage = plt .imshow (Z ,cmap = cmap )
4053colorbar = plt .colorbar (axesimage ,ax = ax ,use_gridspec = True )
4154
42- # helps you see what value you are about to set the range to
55+ # `set_navigate` helps you see what value you are about to set the range
56+ # to, and enables zoom and pan in the colorbar which can be helpful for
57+ # narrow or wide data ranges
4358colorbar .ax .set_navigate (True )
4459
4560# React to all motion with left or right mouse buttons held
46- canvas .mpl_connect ("motion_notify_event" ,motion_fn )
61+ canvas .mpl_connect ("motion_notify_event" ,on_move )
4762
4863# React only to left and right clicks
49- colorbar .ax .axes . set_picker (True )
50- canvas .mpl_connect ("pick_event" ,pick_fn )
64+ colorbar .ax .set_picker (True )
65+ canvas .mpl_connect ("pick_event" ,on_pick )
5166
5267plt .show ()