使用python写一段能将中缀表达式转换为后缀表达式，使用堆栈实现的代码使用英语注释

Here's an example code in Python that converts infix expressions to postfix expressions using stacks:

# A dictionary to store the precedence of operators
precedence = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3}

# A function to check if a character is an operator
def is_operator(char):
    return char in ['+', '-', '*', '/', '^']

# A function to convert infix expressions to postfix expressions
def infix_to_postfix(expression):
    # Initialize an empty stack and an empty list to store the output
    stack = []
    output = []

    # Iterate through each character in the expression
    for char in expression:
        # If the character is an operand, add it to the output
        if not is_operator(char):
            output.append(char)
        # If the character is an operator
        else:
            # Pop operators with higher or equal precedence and add them to the output
            while stack and stack[-1] != '(' and precedence[char] <= precedence[stack[-1]]:
                output.append(stack.pop())
            # Push the current operator onto the stack
            stack.append(char)

        # If the character is a left parenthesis, push it onto the stack
        if char == '(':
            stack.append(char)
        # If the character is a right parenthesis, pop operators until a left parenthesis is found
        if char == ')':
            while stack and stack[-1] != '(':
                output.append(stack.pop())
            # Pop the left parenthesis from the stack
            stack.pop()

    # Pop any remaining operators from the stack and add them to the output
    while stack:
        output.append(stack.pop())

    # Return the postfix expression as a string
    return ''.join(output)

The code above first defines a dictionary `precedence` to store the precedence of operators. Then, it defines a function `is_operator` to check if a character is an operator.

The main function `infix_to_postfix` takes an infix expression as input and returns the postfix expression. It initializes an empty stack and an empty list to store the output. It then iterates through each character in the expression and performs different actions based on the character type.

If the character is an operand, it is added directly to the output list. If the character is an operator, it pops operators with higher or equal precedence from the stack and adds them to the output until it finds an operator with lower precedence or an opening parenthesis. Then, it pushes the current operator onto the stack.

If the character is a left parenthesis, it simply pushes it onto the stack. If the character is a right parenthesis, it pops operators from the stack and adds them to the output until it finds a left parenthesis. It then pops the left parenthesis from the stack.

Finally, it pops any remaining operators from the stack and adds them to the output. The function returns the postfix expression as a string.