如何解决错误消息：'NoneType'对象没有属性'DataFrame'

Question

我从“ Bokeh”官方网站复制了一段代码：

import numpy as np

from bokeh.io import output_file, show
from bokeh.plotting import figure
from bokeh.transform import linear_cmap
from bokeh.util.hex import hexbin

n = 50000
x = np.random.standard_normal(n)
y = np.random.standard_normal(n)

bins = hexbin(x, y, 0.1)

p = figure(tools="wheel_zoom,reset", match_aspect=True, background_fill_color='#440154')
p.grid.visible = False

p.hex_tile(q="q", r="r", size=0.1, line_color=None, source=bins,
           fill_color=linear_cmap('counts', 'Viridis256', 0, max(bins.counts)))

output_file("hex_tile.html")

show(p)

当我运行该程序时，出现以下错误消息： enter image description here

> Traceback (most recent call last): 
> File "d:\vscode-text-files\hex_tile.py", line 12, in 'module'
> bins = hexbin(x, y, 0.1)
> File "D:\Program Files\Python37\lib\site-packages\bokeh\util\hex.py",
> line 198, in hexbin
> df = pd.DataFrame(dict(r=r, q=q))
> AttributeError: 'NoneType' object has no attribute 'DataFrame'

我该如何解决这个问题？