更改 matplotlib 中日期时间轴的格式 [英] Changing the formatting of a datetime axis in matplotlib

问题描述

我有一个索引为 datetime 的系列，我希望绘制它.我想在 y 轴上绘制系列的值，在 x 轴上绘制系列的索引.系列 如下所示:

I have a series whose index is datetime that I wish to plot. I want to plot the values of the series on the y axis and the index of the series on the x axis. The Series looks as follows:

2014-01-01     7
2014-02-01     8
2014-03-01     9
2014-04-01     8
...

我使用 plt.plot(series.index, series.values) 生成图表.但图形看起来像:

I generate a graph using plt.plot(series.index, series.values). But the graph looks like:

问题是我只想有年和月(yyyy-mm 或 2016 年 3 月).但是，该图表包含小时、分钟和秒.如何删除它们以便获得所需的格式?

The problem is that I would like to have only year and month (yyyy-mm or 2016 March). However, the graph contains hours, minutes and seconds. How can I remove them so that I get my desired formatting?

推荐答案

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.dates as mdates

# sample data
N = 30
drange = pd.date_range("2014-01", periods=N, freq="MS")
np.random.seed(365)  # for a reproducible example of values
values = {'values':np.random.randint(1,20,size=N)}
df = pd.DataFrame(values, index=drange)

fig, ax = plt.subplots()
ax.plot(df.index, df.values)
ax.set_xticks(df.index)

# use formatters to specify major and minor ticks
ax.xaxis.set_major_formatter(mdates.DateFormatter("%Y-%m"))
ax.xaxis.set_minor_formatter(mdates.DateFormatter("%Y-%m"))
_ = plt.xticks(rotation=90)    

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