日期刻度标签

演示如何使用日期刻度定位器和格式化程序在matplotlib中创建日期图。有关控制主要和次要刻度的更多信息，请参阅major_minor_demo1.py

所有matplotlib日期绘图都是通过将日期实例转换为自 0001-01-01 00:00:00 UTC 加上一天后的天数（由于历史原因）来完成的。 转换，刻度定位和格式化是在幕后完成的，因此这对您来说是最透明的。 日期模块提供了几个转换器函数 matplotlib.dates.date2num 和matplotlib.dates.num2date。这些可以在datetime.datetime 对象和 numpy.datetime64 对象之间进行转换。

日期刻度标签示例

  1. import numpy as np
  2. import matplotlib.pyplot as plt
  3. import matplotlib.dates as mdates
  4. import matplotlib.cbook as cbook
  6. years = mdates.YearLocator()   # every year
  7. months = mdates.MonthLocator()  # every month
  8. yearsFmt = mdates.DateFormatter('%Y')
  10. # Load a numpy record array from yahoo csv data with fields date, open, close,
  11. # volume, adj_close from the mpl-data/example directory. The record array
  12. # stores the date as an np.datetime64 with a day unit ('D') in the date column.
  13. with cbook.get_sample_data('goog.npz') as datafile:
  14.     r = np.load(datafile)['price_data'].view(np.recarray)
  16. fig, ax = plt.subplots()
  17. ax.plot(r.date, r.adj_close)
  19. # format the ticks
  20. ax.xaxis.set_major_locator(years)
  21. ax.xaxis.set_major_formatter(yearsFmt)
  22. ax.xaxis.set_minor_locator(months)
  24. # round to nearest years...
  25. datemin = np.datetime64(r.date[0], 'Y')
  26. datemax = np.datetime64(r.date[-1], 'Y') + np.timedelta64(1, 'Y')
  27. ax.set_xlim(datemin, datemax)
  30. # format the coords message box
  31. def price(x):
  32.     return '$%1.2f' % x
  33. ax.format_xdata = mdates.DateFormatter('%Y-%m-%d')
  34. ax.format_ydata = price
  35. ax.grid(True)
  37. # rotates and right aligns the x labels, and moves the bottom of the
  38. # axes up to make room for them
  39. fig.autofmt_xdate()
  41. plt.show()

下载这个示例