Question

我可以使用价格数据正确绘制趋势线，但日期格式的X Y轴都是空白。我不确定是什么扰乱了这个轴的绘图配置。这是Python 2.7代码：

y = df['Close']

# calc the trendline http://stackoverflow.com/questions/26447191/how-to-add-trendline-in-python-matplotlib-dot-scatter-graphs

l = []
for t in df['Time']:
    datetime_object = datetime.datetime.strptime(str(t), '%H:%M')
    print datetime_object.hour
    print datetime_object.minute
    l.append((3600 * datetime_object.hour + 60 * datetime_object.minute))
x = l
z = np.polyfit(x, y, 1)
p = np.poly1d(z)
fig = plt.figure()
ax = fig.add_subplot(111)

#http://stackoverflow.com/questions/17709823/plotting-timestamps-hour-minute-seconds-with-matplotlib
plt.xticks(rotation=25)
ax = plt.gca()
ax.set_xticks(x)
xfmt = md.DateFormatter('%H:%M')
ax.xaxis.set_major_formatter(xfmt)

ax.plot(x, p(x), 'r--')
ax.yaxis.set_major_formatter(mtick.FormatStrFormatter('%3.4f')) #http://stackoverflow.com/questions/29188757/matplotlib-specify-format-of-floats-for-tick-lables
plt.show()

此外，df['Close']的值样本为：

114.684
114.679

df['Time']将包含示例值：

23:20
23:21

Answer 1

更新：我找到了问题的根源。

除了以下问题，您错误地将答案复制到了链接的问题。

您写道：ax.yaxis.set_major_formatter(mtick.FormatStrFormatter('%3.4f')) 您需要：ax.yaxis.set_major_formatter(FormatStrFormatter('%3.4f'))

请参阅更新的图表：

https://imgur.com/a/RvO4z

在您的代码中，您可以在实际绘制任何内容之前开始更改轴。

如果您将ax.plot(x, p(x), 'r--')移到add_subplot行的正下方，这将有效：

import numpy as np
from matplotlib import pyplot as plt
import datetime

import matplotlib
from matplotlib.ticker import FormatStrFormatter

df = pandas.DataFrame()
df['Time'] = pandas.Series(['23:2','22:1'])
df['Close'] = pandas.Series([114.,114.])

y = df['Close']

# calc the trendline http://stackoverflow.com/questions/26447191/how-to-add-trendline-in-python-matplotlib-dot-scatter-graphs

l = []
for t in df['Time']:
    datetime_object = datetime.datetime.strptime(str(t), '%H:%M')
    print datetime_object.hour
    print datetime_object.minute
    l.append((3600 * datetime_object.hour + 60 * datetime_object.minute))
x = l
z = np.polyfit(x, y, 1)
p = np.poly1d(z)
fig = plt.figure()
ax = fig.add_subplot(111)
#Added:
ax.plot(x, p(x), 'r--')

#http://stackoverflow.com/questions/17709823/plotting-timestamps-hour-   minute-seconds-with-matplotlib
plt.xticks(rotation=25)
ax = plt.gca()
ax.set_xticks(x)
xfmt = md.DateFormatter('%H:%M')
ax.xaxis.set_major_formatter(xfmt)

# REMOVED: ax.plot(x, p(x), 'r--')
# Changed: ax.yaxis.set_major_formatter(mtick.FormatStrFormatter('%3.4f')) 
ax.yaxis.set_major_formatter(FormatStrFormatter('%3.4f'))
#http://stackoverflow.com/questions/29188757/matplotlib-specify-format-of-    floats-for-tick-lables
plt.show()

对于具有趋势线的日期，Python Matplotlib轴为空白

1 个答案: