Python 在 matplotlib 中绘制熊猫日期
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Plot pandas dates in matplotlib
提问by Gerhard
I have a fixed-width data file containing dates, but when I try to plot the data the dates are not displayed properly on the x-axis.
我有一个包含日期的固定宽度数据文件，但是当我尝试绘制数据时，x 轴上的日期显示不正确。
My files looks like
我的文件看起来像
2014-07-10 11:49:14.377102 45
2014-07-10 11:50:14.449150 45
2014-07-10 11:51:14.521168 21
2014-07-10 11:52:14.574241 8
2014-07-10 11:53:14.646137 11
2014-07-10 11:54:14.717688 14
etc
等等
and I use pandasto read in the file
我用熊猫读入文件
#! /usr/bin/env python
import pandas as pd
import matplotlib.pyplot as plt
data = pd.read_fwf('myfile.log',header=None,names=['time','amount'],widths=[27,5])
data.time = pd.to_datetime(data['time'], format='%Y-%m-%d %H:%M:%S.%f')
plt.plot(data.time,data.amount)
plt.show()
So I suppose the issue here is conversion from pandas to matplotlib datetime, How would one do a conversion?
所以我想这里的问题是从 Pandas 到 matplotlib datetime 的转换，如何进行转换？
I also tried with pandas directly:
我也直接尝试过熊猫：
data.time = pd.to_datetime(data['time'], format='%Y-%m-%d %H:%M:%S.%f')
data.set_index('time') # Fails!!
data.time.plot()
but this fails with
但这失败了
TypeError: Empty 'Series': no numeric data to plot
类型错误：空“系列”：没有要绘制的数字数据
采纳答案by Osmond Bishop
If you use a list containing the column name(s) instead of a string, data.set_index will work
如果您使用包含列名而不是字符串的列表，则 data.set_index 将起作用
The following should show the dates on x-axis:
以下应显示 x 轴上的日期：
#! /usr/bin/env python
import pandas as pd
import matplotlib.pyplot as plt
data = pd.read_fwf('myfile.log',header=None,names=['time','amount'],widths=[27,5])
data.time = pd.to_datetime(data['time'], format='%Y-%m-%d %H:%M:%S.%f')
data.set_index(['time'],inplace=True)
data.plot()
#OR
plt.plot(data.index, data.amount)
