英文:
How to calculate string array with numbers and arithmetic operations
问题
我尝试使用只包含算术符号和数字的数组创建一个计算器，但我不知道如何计算结果，因为我的数组只包含字符串。顺便说一下，我正在使用Python 3.11。
数组示例：
# 示例 1arr = ['2', '*', '2'] # 2x2 = 4 <- 这应该是结果# 示例 2 - 更复杂arr = ['(', '1', '6', '*', '0', ')', '+', '(', '1', '6', '*', '1', ')', '+', '5'] # (16x0) + (16x1) + 5 = 21 <- 这应该是结果
我尝试过使用''.join(arr)将数组连接起来，但它只返回数组中的项目，因为它们都是字符串，而不是结果。
我还尝试过按算术符号拆分数组，并将数字从字符串转换为整数，但是在处理浮点数时遇到了问题，比如1.10、2.42、4.17等等。
英文:
I'm trying to create a calculator using only an array that contains arithmetic symbols and numbers, but I can't figure out how to actually calculate the result since my array will only have strings. By the way, I'm using Python 3.11.
Example of an array:
# Example 1arr = ['2', '*', '2'] # 2x2 = 4 <- This should be the result# Example 2 - More Complexarr = ['(', '1', '6', '*', '0', ')', '+', '(', '1', '6', '*', '1', ')', '+', '5'] # (16x0) + (16x1) + 5 = 21 <- This should be the result
I have tried joining the array using ''.join(arr), but it only returns the items in the array since they are all strings and not the result.
I have tried joining the array using ''.join(arr), but it only returns the items in the array since they are all strings and not the result.
I have also tried splitting the array by the arithmetic simbols and converting the numbers from strings to integers, but I had some problems with floating numbers, such as 1.10, 2.42, 4.17 and so on.
答案1
得分: 2
Here is the translated code:
尝试使用 eval：
def evaluate_expression(arr):expression = ''.join(arr)result = eval(expression)return resultarr = ['2', '*', '2']result = evaluate_expression(arr)print(result) # 输出：4arr = ['(', '1', '6', '*', '0', ')', '+', '(', '1', '6', '*', '1', ')', '+', '5']result = evaluate_expression(arr)print(result) # 输出：21
如果你不想使用 eval() 函数，可以使用堆栈的方式：
def evaluate_expression(arr):precedence = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3}output_queue = []operator_stack = []for token in arr:if token.isdigit() or '.' in token:output_queue.append(token)elif token in precedence:while operator_stack and operator_stack[-1] != '(' and precedence[operator_stack[-1]] >= precedence[token]:output_queue.append(operator_stack.pop())operator_stack.append(token)elif token == '(':operator_stack.append(token)elif token == ')':while operator_stack[-1] != '(':output_queue.append(operator_stack.pop())operator_stack.pop()while operator_stack:output_queue.append(operator_stack.pop())stack = []for token in output_queue:if token.isdigit() or '.' in token:stack.append(float(token))elif token in precedence:operand2 = stack.pop()operand1 = stack.pop()if token == '+':result = operand1 + operand2elif token == '-':result = operand1 - operand2elif token == '*':result = operand1 * operand2elif token == '/':result = operand1 / operand2elif token == '^':result = operand1 ** operand2stack.append(result)return stack.pop()arr = ['2', '*', '2']result = evaluate_expression(arr)print(result) # 输出：4.0arr = ['(', '1', '6', '*', '0', ')', '+', '(', '1', '6', '*', '1', ')', '+', '5']result = evaluate_expression(arr)print(result) # 输出：21.0
英文:
try using eval:
def evaluate_expression(arr):expression = ''.join(arr)result = eval(expression)return resultarr = ['2', '*', '2']result = evaluate_expression(arr)print(result) # Output: 4arr = ['(', '1', '6', '*', '0', ')', '+', '(', '1', '6', '*', '1', ')', '+', '5']result = evaluate_expression(arr)print(result) # Output: 21
if you dont want to use eval() function, the labor way would be using stack:
def evaluate_expression(arr):precedence = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3}output_queue = []operator_stack = []for token in arr:if token.isdigit() or '.' in token:output_queue.append(token)elif token in precedence:while operator_stack and operator_stack[-1] != '(' and precedence[operator_stack[-1]] >= precedence[token]:output_queue.append(operator_stack.pop())operator_stack.append(token)elif token == '(':operator_stack.append(token)elif token == ')':while operator_stack[-1] != '(':output_queue.append(operator_stack.pop())operator_stack.pop()while operator_stack:output_queue.append(operator_stack.pop())stack = []for token in output_queue:if token.isdigit() or '.' in token:stack.append(float(token))elif token in precedence:operand2 = stack.pop()operand1 = stack.pop()if token == '+':result = operand1 + operand2elif token == '-':result = operand1 - operand2elif token == '*':result = operand1 * operand2elif token == '/':result = operand1 / operand2elif token == '^':result = operand1 ** operand2stack.append(result)return stack.pop()arr = ['2', '*', '2']result = evaluate_expression(arr)print(result) # Output: 4.0arr = ['(', '1', '6', '*', '0', ')', '+', '(', '1', '6', '*', '1', ')', '+', '5']result = evaluate_expression(arr)print(result) # Output: 21.0
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