直方图hist函数解释

当直方图有多列时，默认逐列分别做直方图

hist(
column=None,
by=None,
grid=True,
xlabelsize=None,
xrot=None,
ylabelsize=None,
yrot=None,
ax=None,
sharex=False,
sharey=False,
figsize=None,
layout=None,
bins=10,
**kwds,
)

https://matplotlib.org/gallery/statistics/hist.html#sphx-glr-gallery-statistics-hist-py