pandas / matplotlib：如何在绘图的 x 轴上显示所有年份？

Question

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.ticker as ticker
import matplotlib.markers as markers
from datetime import datetime as dt

df = pd.DataFrame(
    {
        'date': ['2011-01-01', '2011-02-01', '2012-01-01', '2012-02-01', ],
        'amount': [100, 200, 250, 150,],
    }
)
df.date = pd.to_datetime(df.date)

df_TotalDay = df[['date','amount']].copy(deep=True)
df_TotalDay = df_TotalDay.groupby('date').amount.sum()
df_TotalDay

fig, ax = plt.subplots(figsize=(15,5))
ax.plot(df_TotalDay.index, df_TotalDay.values)
plt.xticks([x for x in df_TotalDay.index])
plt.show()

在上面的图中，我只想显示唯一的年份。在这里，它只是“2011”和“2012”而不是实际日期。

我试过了

plt.xticks([x for x in df_TotalDay.index.year.unique()])

但这没有用。

我知道上面的 DataFrame 看起来有点傻，但我的实际 DataFrame 非常大，当我绘制数据时，它看起来像这样：

在上图中，matplotlib 并不是每年都在 x 轴上列出。我想包括缺失的年份。

Answer 1

你们很亲近。您应该生成所有要显示的日期，然后添加到 xticks:

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

df = pd.DataFrame(
    {
        'date': ['2011-01-01', '2013-02-01', '2016-01-01', '2018-02-01', ],
        'amount': [100, 200, 250, 150,],
    }
)
df.date = pd.to_datetime(df.date)
df_TotalDay = df[['date','amount']].copy(deep=True)
df_TotalDay = df_TotalDay.groupby('date').amount.sum()

fig, ax = plt.subplots(figsize=(15,5))
ax.plot(df_TotalDay.index, df_TotalDay.values)
plt.xticks(pd.date_range(df_TotalDay.index.min(), df_TotalDay.index.max(), freq='YS'))
plt.show()

要仅显示年份，您可以使用

import matplotlib.dates as mdates
ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y'))

Answer 2

Z Li 答案的替代方法是使用 matplotlibs dates.YearLocator

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib
from datetime import datetime as dt

df = pd.DataFrame(
    {
        'date': ['2011-01-01', '2011-02-01', '2012-01-01', '2012-02-01', ],
        'amount': [100, 200, 250, 150,],
    }
)
df.date = pd.to_datetime(df.date)

df_TotalDay = df[['date','amount']].copy(deep=True)
df_TotalDay = df_TotalDay.groupby('date').amount.sum()

fig, ax = plt.subplots(figsize=(15,5))
ax.plot(df_TotalDay.index, df_TotalDay.values)
ax.set_xlabel('Year')
ax.minorticks_off()
ax.xaxis.set_major_locator(matplotlib.dates.YearLocator())
ax.xaxis.set_major_formatter(matplotlib.dates.DateFormatter("%Y"))

pandas / matplotlib：如何在绘图的 x 轴上显示所有年份？

pandas / matplotlib : How do I show all years on the x-axis of my plot?

python

matplotlib

pandas