如何使用PyQt计算应用程序中字符的出现次数

from PyQt5.QtWidgets import QApplication, QMainWindow, QTextEdit, QPushButton
from PyQt5.QtCore import Qt

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.setWindowTitle("字符出现次数计算")
        self.setGeometry(100, 100, 400, 300)

        self.textEdit = QTextEdit(self)
        self.textEdit.setGeometry(10, 10, 380, 200)

        self.button = QPushButton("计算", self)
        self.button.setGeometry(150, 220, 100, 30)
        self.button.clicked.connect(self.calculate)

    def calculate(self):
        text = self.textEdit.toPlainText()
        char_count = len(text)
        char_freq = {}
        for char in text:
            char_freq[char] = char_freq.get(char, 0) + 1

        result = "字符总数：{}\n".format(char_count)
        result += "字符出现次数：\n"
        for char, freq in char_freq.items():
            result += "{}: {}\n".format(char, freq)

        self.textEdit.setText(result)

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec_()