正在更新matplotlib barchart

Question

我是matplotlib的新手，正在尝试从MySQL数据库中的数据制作条形图。条形图工作正常，但是当程序运行时将新记录添加到数据库中时，条形图不会更新。为了在条形图中显示新值，需要关闭并再次打开程序。这是我在tkinter gui中每次按下按钮时执行的功能的代码，我知道这可能不是解决此问题的最佳方法。我希望在按下按钮时更新条形图。有任何提示吗？

def graphs(self):
    self.cursor.execute('SELECT * FROM Enrollment; ')
    result = self.cursor.fetchall()

    economics = 0
    information_science = 0
    data_science = 0
    mathematics = 0
    politics = 0
    history = 0
    information_sec = 0
    music = 0
    medicine = 0
    business = 0

    for row in result:
        if row[2] == 1:
            economics += 1
        elif row[2] == 2:
            information_science += 1
        elif row[2] == 3:
            data_science += 1
        elif row[2] == 4:
            mathematics += 1
        elif row[2] == 5:
            politics += 1
        elif row[2] == 6:
            history += 1
        elif row[2] == 7:
            information_sec += 1
        elif row[2] == 8:
            music += 1
        elif row[2] == 9:
            medicine += 1
        elif row[2] == 10:
            business += 1

    values = [economics, information_science, data_science, mathematics, politics,
              history, information_sec, music, medicine, business]
    keys = ['Economics', 'Information Science', 'Data Science', 'Mathematics', 'Politics',
            'History', 'Information Security', 'Music Studies', 'Medicine', 'Business Analytics']
    plt.bar(keys, values, zorder=3)
    plt.title('Students in each course')
    plt.xlabel('Courses')
    plt.ylabel('Students')
    plt.xticks(keys, rotation='vertical')
    plt.subplots_adjust(bottom=0.35)
    plt.grid(zorder=0)
    plt.show()

Answer 1

您可以保存多张图像而不必关闭程序：

count = 0

    plt.savefig('bar'+str(count)+'.png')
    count += 1

Answer 2

这解决了我的问题。使用SQL计数值也极大地简化了我的代码。

def graphs(self):
    self.cursor.execute('SELECT Course_ID, Count(*) FROM Enrollment GROUP BY Course_ID; ')
    result = self.cursor.fetchall()

    df = DataFrame(result)
    keys = ['Economics', 'Information Science', 'Data Science', 'Mathematics', 'Politics',
            'History', 'Information Security', 'Music Studies', 'Medicine', 'Business Analytics']
    values = df[1]
    plt.bar(keys, values, zorder=3)
    plt.title('Students in each course')
    plt.xlabel('Courses')
    plt.ylabel('Students')
    plt.xticks(keys, rotation='vertical')
    plt.subplots_adjust(bottom=0.35)
    plt.grid(zorder=0)
    plt.show()