二十三、共享 X 轴

在这个 Matplotlib 数据可视化教程中，我们将讨论sharex选项，它允许我们在图表之间共享x轴。将sharex看做『复制 x』也许更好。

在我们开始之前，首先我们要做些修剪并在另一个轴上设置最大刻度数，如下所示：

  1. ax2.yaxis.set_major_locator(mticker.MaxNLocator(nbins=7, prune='upper'))

以及

  1. ax3.yaxis.set_major_locator(mticker.MaxNLocator(nbins=4, prune='upper'))

现在，让我们共享所有轴域之间的x轴。 为此，我们需要将其添加到轴域定义中：

  1. fig = plt.figure()
  2. ax1 = plt.subplot2grid((6,1), (0,0), rowspan=1, colspan=1)
  3. plt.title(stock)
  4. plt.ylabel('H-L')
  5. ax2 = plt.subplot2grid((6,1), (1,0), rowspan=4, colspan=1, sharex=ax1)
  6. plt.ylabel('Price')
  7. ax3 = plt.subplot2grid((6,1), (5,0), rowspan=1, colspan=1, sharex=ax1)
  8. plt.ylabel('MAvgs')

上面，对于ax2和ax3，我们添加一个新的参数，称为sharex，然后我们说，我们要与ax1共享x轴。

使用这种方式，我们可以加载图表，然后我们可以放大到一个特定的点，结果将是这样：

二十三、共享 X 轴 - 图1

所以这意味着所有轴域沿着它们的x轴一起移动。 这很酷吧！

接下来，让我们将[-start:]应用到所有数据，所以所有轴域都起始于相同地方。 我们最终的代码为：

  1. import matplotlib.pyplot as plt
  2. import matplotlib.dates as mdates
  3. import matplotlib.ticker as mticker
  4. from matplotlib.finance import candlestick_ohlc
  5. from matplotlib import style
  7. import numpy as np
  8. import urllib
  9. import datetime as dt
  11. style.use('fivethirtyeight')
  12. print(plt.style.available)
  14. print(plt.__file__)
  16. MA1 = 10
  17. MA2 = 30
  19. def moving_average(values, window):
  20.     weights = np.repeat(1.0, window)/window
  21.     smas = np.convolve(values, weights, 'valid')
  22.     return smas
  24. def high_minus_low(highs, lows):
  25.     return highs-lows
  28. def bytespdate2num(fmt, encoding='utf-8'):
  29.     strconverter = mdates.strpdate2num(fmt)
  30.     def bytesconverter(b):
  31.         s = b.decode(encoding)
  32.         return strconverter(s)
  33.     return bytesconverter
  36. def graph_data(stock):
  38.     fig = plt.figure()
  39.     ax1 = plt.subplot2grid((6,1), (0,0), rowspan=1, colspan=1)
  40.     plt.title(stock)
  41.     plt.ylabel('H-L')
  42.     ax2 = plt.subplot2grid((6,1), (1,0), rowspan=4, colspan=1, sharex=ax1)
  43.     plt.ylabel('Price')
  44.     ax3 = plt.subplot2grid((6,1), (5,0), rowspan=1, colspan=1, sharex=ax1)
  45.     plt.ylabel('MAvgs')
  48.     stock_price_url = 'http://chartapi.finance.yahoo.com/instrument/1.0/'+stock+'/chartdata;type=quote;range=1y/csv'
  49.     source_code = urllib.request.urlopen(stock_price_url).read().decode()
  50.     stock_data = []
  51.     split_source = source_code.split('\n')
  52.     for line in split_source:
  53.         split_line = line.split(',')
  54.         if len(split_line) == 6:
  55.             if 'values' not in line and 'labels' not in line:
  56.                 stock_data.append(line)
  59.     date, closep, highp, lowp, openp, volume = np.loadtxt(stock_data,
  60.                                                           delimiter=',',
  61.                                                           unpack=True,
  62.                                                           converters={0: bytespdate2num('%Y%m%d')})
  64.     x = 0
  65.     y = len(date)
  66.     ohlc = []
  68.     while x < y:
  69.         append_me = date[x], openp[x], highp[x], lowp[x], closep[x], volume[x]
  70.         ohlc.append(append_me)
  71.         x+=1
  73.     ma1 = moving_average(closep,MA1)
  74.     ma2 = moving_average(closep,MA2)
  75.     start = len(date[MA2-1:])
  77.     h_l = list(map(high_minus_low, highp, lowp))
  80.     ax1.plot_date(date[-start:],h_l[-start:],'-')
  81.     ax1.yaxis.set_major_locator(mticker.MaxNLocator(nbins=4, prune='lower'))
  84.     candlestick_ohlc(ax2, ohlc[-start:], width=0.4, colorup='#77d879', colordown='#db3f3f')
  88.     ax2.yaxis.set_major_locator(mticker.MaxNLocator(nbins=7, prune='upper'))
  89.     ax2.grid(True)
  91.     bbox_props = dict(boxstyle='round',fc='w', ec='k',lw=1)
  93.     ax2.annotate(str(closep[-1]), (date[-1], closep[-1]),
  94.                  xytext = (date[-1]+4, closep[-1]), bbox=bbox_props)
  97. ##    # Annotation example with arrow
  98. ##    ax2.annotate('Bad News!',(date[11],highp[11]),
  99. ##                 xytext=(0.8, 0.9), textcoords='axes fraction',
  100. ##                 arrowprops = dict(facecolor='grey',color='grey'))
  101. ##
  102. ##    
  103. ##    # Font dict example
  104. ##    font_dict = {'family':'serif',
  105. ##                 'color':'darkred',
  106. ##                 'size':15}
  107. ##    # Hard coded text 
  108. ##    ax2.text(date[10], closep[1],'Text Example', fontdict=font_dict)
  112.     ax3.plot(date[-start:], ma1[-start:], linewidth=1)
  113.     ax3.plot(date[-start:], ma2[-start:], linewidth=1)
  115.     ax3.fill_between(date[-start:], ma2[-start:], ma1[-start:],
  116.                      where=(ma1[-start:] < ma2[-start:]),
  117.                      facecolor='r', edgecolor='r', alpha=0.5)
  119.     ax3.fill_between(date[-start:], ma2[-start:], ma1[-start:],
  120.                      where=(ma1[-start:] > ma2[-start:]),
  121.                      facecolor='g', edgecolor='g', alpha=0.5)
  123.     ax3.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m-%d'))
  124.     ax3.xaxis.set_major_locator(mticker.MaxNLocator(10))
  125.     ax3.yaxis.set_major_locator(mticker.MaxNLocator(nbins=4, prune='upper'))
  127.     for label in ax3.xaxis.get_ticklabels():
  128.         label.set_rotation(45)
  132.     plt.setp(ax1.get_xticklabels(), visible=False)
  133.     plt.setp(ax2.get_xticklabels(), visible=False)
  134.     plt.subplots_adjust(left=0.11, bottom=0.24, right=0.90, top=0.90, wspace=0.2, hspace=0)
  135.     plt.show()
  138. graph_data('EBAY')

下面我们会讨论如何创建多个y轴。