matplotlib.widgets.Slider with histogram

Question

I'm trying to make the interactive histogram but during

update old histogram is not been cleared, as shown in the image below.

)

above plot is generated using following code

from functools import lru_cache
import scipy.stats as ss
import matplotlib.pyplot as plt
import matplotlib.widgets as widgets

fig, ax = plt.subplots()
plt.subplots_adjust(bottom=0.25)

weight = ss.lognorm(0.23, 0, 70.8)

@lru_cache
def sampling(n):
    return [ weight.rvs().mean() for i in range(1000) ]

theme = {
    'color' : "#1f77b4",
    'alpha' : 0.7,
}

t = ax.hist(sampling(100), **theme)

slider = widgets.Slider(
    ax      = plt.axes([0.25, 0.1, 0.5, 0.03]),
    label   = "n",
    valmin  = 10,
    valmax  = 1000,
    valinit = 100,
    valstep = 1

def update(val):
    global t
    del t
    t = ax.hist(sampling(int(val)), **theme)
    fig.canvas.draw_idle()

slider.on_changed(update)
ax.set_title('Distribution of Sample Size Mean')
plt.show()

Andrew Micallef · Accepted Answer · 2020-05-28T10:17:38.170

3

ax.hist is returning a tuple containing the number of bins, the edges of the bins and then the patches... you thus need to capture the patches and remove them in update.

You need to use t.remove() in update, as in:

*_, patches = ax.hist()

def update(val):
    global patches
    for p in patches:
        p.remove()

    *_, patches = ax.hist(sampling(int(val)), **theme)
    fig.canvas.draw_idle()

edited May 28 '20 at 10:17

answered May 28 '20 at 10:06

Andrew Micallef

360
1
10

if i do that `AttributeError: 'tuple' object has no attribute 'remove''`, problem is `t` is a tuple and remove is not available. – rho May 28 '20 at 10:10
1

haha, my mistake, ax.hist() is returning a tuple, which yeah, is the problem. – Andrew Micallef May 28 '20 at 10:15
1

I got the inside scoop it seams. Does the above work for you? – Andrew Micallef May 28 '20 at 10:18
ya found out this post https://stackoverflow.com/questions/40409977/how-to-remove-an-histogram-in-matplotlib i guess yours works too – rho May 28 '20 at 10:20
shame, looks like this'll be marked as a duplicate I guess. Also You really should turn t into a data class :P – Andrew Micallef May 28 '20 at 10:21
may be, i was focused on slider thing, totally forgot how hist works!. hardest part in to name something – rho May 28 '20 at 10:23
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/214814/discussion-between-andrew-micalled-and-rho). – Andrew Micallef May 28 '20 at 10:26

matplotlib.widgets.Slider with histogram

1 Answers1