matplotlib.pyplot:dates

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"""
    demo12_loadtxt.py aapl.csv文件读取
"""
import numpy as np
import datetime as dt
import matplotlib.pyplot as plt
import matplotlib.dates as md

def dmy2ymd(dmy):
    dmy = str(dmy, encoding='utf-8')
    time = dt.datetime.strptime(dmy, '%d-%m-%Y').date()
    t = time.strftime('%Y-%m-%d')
    return t

# dtype中的dates为M8[D], <class 'numpy.ndarray'>
dates, opening_prices, highest_prices,\
    lowest_prices, closing_prices = np.loadtxt(
    '../data/aapl.csv', delimiter=',',
    usecols=(1, 3, 4, 5, 6), unpack=True,
    dtype='M8[D], f8, f8, f8, f8',
    converters={1: dmy2ymd} # 转换器函数
)


# 绘制收盘价折线图
plt.figure('AAPL K', facecolor='lightgray')
plt.title('AAPL K', fontsize=16)
plt.xlabel('Day', fontsize=14)
plt.ylabel('Price', fontsize=14)
plt.tick_params(labelsize=10)
plt.grid(linestyle=':')

# 为了日期显示合理，修改dates的dtype
dates = dates.astype(md.datetime.datetime)
# 设置x轴刻度定位器
ax = plt.gca()
#设置主刻度定位器为周定位器（每周一显示主刻度文本）
ax.xaxis.set_major_locator(md.WeekdayLocator(byweekday=md.MO))
ax.xaxis.set_major_formatter(md.DateFormatter('%d %b %Y'))

#设置次刻度定位器为日定位器
ax.xaxis.set_minor_locator(md.DayLocator())
plt.tick_params(labelsize=8)

plt.plot(dates, closing_prices,
         color='dodgerblue', linewidth=2,
         linestyle='--', label='AAPL CP')

plt.legend()
plt.gcf().autofmt_xdate()
plt.savefig('Apple_stock_prices_with_dates.png')
plt.show()

Apple_stock_prices_with_dates.png