python matplotlib刻度（含日期刻度处理），标签，网格

Posted 2021-05-09

# from pylab import *


# TODO 为什么这个函数不生效, 还不清楚
# nbins是调整某个轴的刻度被几分的
# locator_params('x', nbins=10)
# plot(np.random.normal(10, .1, 100))

# 我们还可以手动设置刻度的数量和标签, 例如 '%1.1f cm'就是一个合法的标签格式

# 对于日期的处理, 我们可以借助matplotlib.dates.date2num(), 
# matplotlib. dates.num2date(), and matplotlib.dates.drange()等函数来转换,
# 下面是一个例子
from pylab import *
import matplotlib as mpl
import datetime

fig = figure()

# set some daterange
start = datetime.datetime(2013, 1, 1)
stop = datetime.datetime(2013, 12, 31)
delta = datetime.timedelta(days = 1)

# convert dates for matplotlib
dates = mpl.dates.drange(start, stop, delta)

# generate some random values
values = np.random.rand(len(dates))

ax = gca()

# create plot with dates
ax.plot_date(dates, values, linestyle='-', marker='')

# specify formater
date_format = mpl.dates.DateFormatter('%Y-%m-%d')

# apply formater
ax.xaxis.set_major_formatter(date_format)

# autoformat date labels
# rotates labels by 30 degrees by default
# use rotate param to specify different rotation degree
# use bottom param to give more room to date labels
fig.autofmt_xdate()

show()