Algorithm python中的中缀到后缀算法

对于我的数据结构类，我必须使用Python3创建一个基本的图形计算器。要求是我们必须使用一个基本的堆栈类。用户以“中缀”形式输入等式，然后我将其转换为“后缀”进行计算和绘图。我在中缀到后缀的算法上遇到了问题。我见过其他可以工作的算法，但我的教授希望它以某种方式完成。以下是我目前掌握的情况：

def inFixToPostFix():
inFix = '3*(x+1)-2/2'
postFix = ''
s = Stack()
for c in inFix:
    # if elif chain for anything that c can be
    if c in "0123456789x":
        postFix += c
    elif c in "+-":
        if s.isEmpty():
            s.push(c)
        elif s.top() =='(':
            s.push(c)
    elif c in "*/":
        if s.isEmpty():
            s.push(c)
        elif s.top() in "+-(":
            s.push(c)
    elif c == "(":
        s.push(c)
    elif c == ")":
        while s.top() is not '(':
            postFix += s.pop()
        s.pop()
    else:
        print("Error")
print(postFix)
return postFix

当我打印此文件时，当预期结果为“3x1+*22/-”时，我得到“3x1+22”

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任何帮助都将不胜感激。谢谢。

退出循环后，应该在堆栈上弹出剩余的操作数。该算法非常简单，但如果您需要信息，此处将解释：

如果您需要，这里是我的解决方案版本：）

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为了使算法正确，需要对其进行大量修改

将这种类型的字符串表示法用于后缀字符串，稍后在对其求值时，您可能会发现- 2+34和23+4的表示形式相同，即234+

如果遇到的操作数的优先级低于操作数堆栈顶部的优先级，请从操作数堆栈弹出并将其推送到后缀堆栈（您尚未执行此操作）

完成给定中缀字符串的遍历后，操作数堆栈中的剩余操作数应从中缀字符串中弹出并推送到后缀堆栈中

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这是数据结构课程的初始任务之一，因为它真正认可了堆栈的使用。因此我不会分享我的代码，因为我认为你可以自己完成。仍然有困难，分享障碍，我将引导您到达目的地。

您需要显示代码的输出，并解释输出如何与预期不符。这是我关于stackoverflow的第一篇文章。我甚至没有想到要把返回值和期望的返回值放在一起。谢谢您需要在转换结束时弹出堆栈，或者可以在调用中缀到后缀函数之前在整个表达式周围加上括号。你明白为什么这两种解决方案是等价的吗？谢谢！在你的代码和你发布的链接之间，我已经做了一些工作，我只是在做一些bug修复。如果输入像（10+20）*30，我怀疑你的代码是否可以正常工作？我试着运行你提供的链接，但我没有正确打印它，因为字符串读取不好。我的建议是首先删除所有空格，然后在操作符前后引入一个空格，然后进行拆分并继续for循环。这个词就是“算法”。它来源于某人的名字。不是“Algo”。

class stack:
def __init__(self):
    self.item = []

def push(self,it):
    self.item.append(it)
def peek(self):
    if self.isempty() == True:
        return 0
    return self.item[-1]

def pop(self):
    if self.isempty() == True:
        return 0
    return(self.item.pop())

def length(self):
    return (len(self.item))


def isempty(self):
    if self.item == []:
        return True
    else:
        return False

def display(self):
    if self.isempty()== True:
        return
    temps = stack()
    while(self.isempty() != True):
        x = self.peek()
        print("~",x)
        temps.push(x)
        self.pop()
    while(temps.isempty() != True):
        x = temps.peek()
        self.push(x)
        temps.pop()


def isOperand(self, ch): 
    return ch.isalpha()
def notGreater(self, i):
    precedence = {'+':1, '-':1, '*':2, '/':2, '%':2, '^':3}
    if self.peek() == '(':
        return False
    a = precedence[i]
    b = precedence[self.peek()] 
    if a  <= b:
        return True
    else:
        return False
        


def infixToPostfix(self, exp):
    output = ""
    
    for i in exp:
        
        if self.isOperand(i) == True: # check if operand add to output
            print(i,"~ Operand push to stack")
            output = output + i

        # If the character is an '(', push it to stack 
        elif i  == '(':
            self.push(i)
            print(i," ~ Found ( push into stack")

        elif i == ')':  # if ')' pop till '('
            while( self.isempty() != True and self.peek() != '('):
                n = self.pop() 
                output = output + n
                print(n, "~ Operator popped from stack")
            if (self.isempty() != True and self.peek() != '('):
                print("_________")
                return -1
            else:
                x = self.pop()
                print(x, "Popping and deleting (")
        else: 
            while(self.isempty() != True and self.notGreater(i)):
                c = self.pop()
                output = output + c
                print(c,"Operator popped after checking precedence from stack")
            self.push(i)
            print(i,"Operator pushed to stack")

    # pop all the operator from the stack 
    while self.isempty() != True:
        xx = self.pop()
        output = output + xx
        print(xx,"~ pop at last")
    print(output)
    self.display()
st = stack()
st.infixToPostfix("a+(b*c)")

class stack:
def __init__(self):
    self.item = []

def push(self,it):
    self.item.append(it)
def peek(self):
    if self.isempty() == True:
        return 0
    return self.item[-1]

def pop(self):
    if self.isempty() == True:
        return 0
    return(self.item.pop())

def length(self):
    return (len(self.item))


def isempty(self):
    if self.item == []:
        return True
    else:
        return False

def display(self):
    if self.isempty()== True:
        return
    temps = stack()
    while(self.isempty() != True):
        x = self.peek()
        print("~",x)
        temps.push(x)
        self.pop()
    while(temps.isempty() != True):
        x = temps.peek()
        self.push(x)
        temps.pop()


def isOperand(self, ch): 
    return ch.isalpha()
def notGreater(self, i):
    precedence = {'+':1, '-':1, '*':2, '/':2, '%':2, '^':3}
    if self.peek() == '(':
        return False
    a = precedence[i]
    b = precedence[self.peek()] 
    if a  <= b:
        return True
    else:
        return False
        


def infixToPostfix(self, exp):
    output = ""
    
    for i in exp:
        
        if self.isOperand(i) == True: # check if operand add to output
            print(i,"~ Operand push to stack")
            output = output + i

        # If the character is an '(', push it to stack 
        elif i  == '(':
            self.push(i)
            print(i," ~ Found ( push into stack")

        elif i == ')':  # if ')' pop till '('
            while( self.isempty() != True and self.peek() != '('):
                n = self.pop() 
                output = output + n
                print(n, "~ Operator popped from stack")
            if (self.isempty() != True and self.peek() != '('):
                print("_________")
                return -1
            else:
                x = self.pop()
                print(x, "Popping and deleting (")
        else: 
            while(self.isempty() != True and self.notGreater(i)):
                c = self.pop()
                output = output + c
                print(c,"Operator popped after checking precedence from stack")
            self.push(i)
            print(i,"Operator pushed to stack")

    # pop all the operator from the stack 
    while self.isempty() != True:
        xx = self.pop()
        output = output + xx
        print(xx,"~ pop at last")
    print(output)
    self.display()
st = stack()
st.infixToPostfix("a+(b*c)")

a ~ Operand push to stack
+ Operator pushed to stack
(  ~ Found ( push into stack
b ~ Operand push to stack
* Operator pushed to stack
c ~ Operand push to stack
* ~ Operator popped from stack
( Popping and deleting (
+ ~ pop at last
abc*+