Python中的 Matplotlib.dates.DateFormatter 类

Matplotlib是Python中用于数组二维图的惊人可视化库。 Matplotlib 是一个基于 NumPy 数组构建的多平台数据可视化库，旨在与更广泛的 SciPy 堆栈配合使用。

Matplotlib.dates.DateFormatter

matplotlib.dates.DateFormatter类用于使用 strftime 格式的字符串格式化刻度（自纪元以来的秒数）。它的基类是matplotlib.ticker.Formatter 。

Syntax: class matplotlib.dates.DateFormatter(fmt, tz=None)

Parameters:

1. fmt: It accepts a strftime format string for formatting and is a required argument.
2. tz: It holds information regarding the timezone. If set to none it ignores the timezone information while formatting of the date string.

示例 1：

import numpy
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import pandas
  
   
total_bars = 25
numpy.random.seed(total_bars)
   
dates = pandas.date_range('3/4/2020', 
                          periods=total_bars,
                          freq='m')
  
diff = pandas.DataFrame(
    data=numpy.random.randn(total_bars), 
    index=dates,
    columns=['A']
)
   
figure, axes = plt.subplots(figsize=(10, 6))
  
axes.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m'))
  
axes.bar(diff.index,
         diff['A'], 
         width=25, 
         align='center')

输出：

示例 2：

import matplotlib
import matplotlib.pyplot as plt
from datetime import datetime
  
origin = ['2020-02-05 17:17:55',
          '2020-02-05 17:17:51', 
          '2020-02-05 17:17:49']
  
a = [datetime.strptime(d, '%Y-%m-%d %H:%M:%S') for d in origin]
  
b = ['35.764299', '20.3008', '36.94704']
  
x = matplotlib.dates.date2num(a)
formatter = matplotlib.dates.DateFormatter('%H:%M:%S')
  
figure = plt.figure()
axes = figure.add_subplot(1, 1, 1)
  
axes.xaxis.set_major_formatter(formatter)
plt.setp(axes.get_xticklabels(), rotation = 15)
  
axes.plot(x, b)
plt.show()

输出：