我如何绘制一个图表，其中每个月的值都显示在 x 标签中，只显示年份？在 Matplotlib.Pyplot 中

Question

    cur.execute( """ SELECT sum(value), Extract ('month' from dateOperation), Extract ('year' from dateOperation) FROM movimenti GROUP BY (Extract ('month' from dateOperation)), (Extract ('year' from dateOperation)) ORDER BY (Extract ('year' from dateOperation)) , (Extract ('month' from dateOperation)) """ ) 

    data = cur.fetchall()
    counts, month, year = zip(*data)
    
    plt.plot(list(map(lambda x: f"{int(month[x])}/{int(year[x])}", range(len(month)))), counts, marker='o', color='green',linewidth=3,alpha=0.8,label='Totale')
    plt.title('Bilancio annuo:')
    plt.xlabel('Data')
    plt.ylabel('Valore')
    plt.axhline(y=0, color='black', linestyle='--', linewidth=1, label='Zero',alpha=0.5)
    plt.grid(True)
    plt.legend()

    plt.show()

这是我的代码

它访问数据库检索付款月份和年份的值，您可以在下图中看到结果。

我希望不是在 xlabel 中显示所有月份，而是每年有一个显示年份，还有两条垂直线显示该年结束和下一年开始的时间，但保持图表的每月粒度

Answer 1

尝试一下，看看是否有效。不确定这是否正是您所需要的，但也许它可以帮助您：

import matplotlib.pyplot as plt
import matplotlib.dates as mdates
from datetime import datetime

counts, months, years = zip(*data)

dates = [datetime(int(y), int(m), 1) for y, m in zip(years, months)]

plt.figure(figsize=(10, 5))
plt.plot(dates, counts, marker='o', color='green', linewidth=3, alpha=0.8, label='Totale')

# Set the locator for x-ticks to the first month of each year
plt.gca().xaxis.set_major_locator(mdates.YearLocator(month=1, day=1))
# Format the x-tick labels to show only the year
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter('%Y'))
# Add vertical lines and labels for each year
unique_years = sorted(set(years))
for year in unique_years:
    plt.axvline(datetime(int(year), 1, 1), color='red', linestyle='--', linewidth=1, alpha=0.5)

plt.title('Bilancio annuo:')
plt.xlabel('Data')
plt.ylabel('Valore')

plt.axhline(y=0, color='black', linestyle='--', linewidth=1, label='Zero', alpha=0.5)
plt.grid(True)
plt.legend()
plt.tight_layout() 
plt.xticks(rotation=45)
plt.show()