how to display the all intervals in colorbar using matplotlib

Question

This is my code.I mentioned here 50 intervals,when i drag the slider then only i got 6 or 7 intervals,but i want to display the all my intervals in my colorbar. So can any one please guide me.Thank you in advance.

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider, Button
import matplotlib.colors
ax = plt.subplot(111)
plt.subplots_adjust(left=0.25, bottom=0.25)
img_data = np.random.rand(50,50)

c_max = 2
img = ax.imshow(img_data, interpolation='nearest')
cb = plt.colorbar(img)
axcolor = 'lightgoldenrodyellow'
ax_cmax  = plt.axes([0.25, 0.15, 0.65, 0.03])
s_cmax = Slider(ax_cmax, 'max', 0, 50, valfmt=c_max)
def update(val, s=None):
    # _cmin = s_cmin.val
    _cmax = s_cmax.val
    img.set_clim(_cmax)
    plt.draw()
s_cmax.on_changed(update)

plt.show()

Answer 1

The argument to Slider called valfmt should be a string which is used to format the slider value.

So if you wanted to display 2 decimal places to the float you would need to make c_max = "%1.2f". Note that if you want to keep the minimum value at 0 you need to set that too in img.set_clim(0, _cmax)

c_max = "%1.2f"
img = ax.imshow(img_data, interpolation='nearest')
cb = plt.colorbar(img)
axcolor = 'lightgoldenrodyellow'
ax_cmax  = plt.axes([0.25, 0.15, 0.65, 0.03])
s_cmax = Slider(ax_cmax, 'max', 0, 50, valfmt=c_max)
def update(val, s=None):
    # _cmin = s_cmin.val
    _cmax = s_cmax.val
    img.set_clim(0, _cmax) 
    plt.draw()
s_cmax.on_changed(update)

plt.show()