def postfix_from(self, infix):
infix = self.__prepare(infix)
prec = {}
prec["^"] = 4
prec["*"] = 3
prec["/"] = 3
prec["+"] = 2
prec["-"] = 2
prec["("] = 1
opStack = Stack()
postfixList = []
tokenList = infix.split()
for token in tokenList:
if self.__is_number(token) or token == "pi" or token == "e":
postfixList.append(token)
elif token == '(':
opStack.push(token)
elif token == ')':
topToken = opStack.pop()
while topToken != '(':
postfixList.append(topToken)
topToken = opStack.pop()
else:
while (not opStack.isEmpty()) and \
(prec[opStack.peek()] >= prec[token]):
postfixList.append(opStack.pop())
opStack.push(token)
while not opStack.isEmpty():
postfixList.append(opStack.pop())
return " ".join(postfixList)
def postfix_converter(infixstring):
op_stack = Stack()
output_list = []
infix_list = infixstring.split(' ')
operators = '*/+-'
for char in infix_list:
if char == '(':
op_stack.push(char)
elif char == ')':
prior_op = op_stack.pop()
while prior_op != '(':
output_list.append(prior_op)
prior_op = op_stack.pop()
elif char in operators:
if op_stack.contains_items() and op_stack.peek() in '*/':
output_list.append(op_stack.pop())
op_stack.push(char)
else:
op_stack.push(char)
else:
output_list.append(char)
while op_stack.contains_items():
output_list.append(op_stack.pop())
return " ".join(output_list)
def infixxer(postfix):
s = Stack()
l = len(postfix)
for i in range(l):
if (isOperator(postfix[i])):
temp = s.pop()
temp2 = '(' + s.pop() + postfix[i] + temp + ')'
s.push(temp2)
else:
s.push(postfix[i])
return s.peek()
def postfixxer(prefix):
s=Stack()
l=len(prefix)
for i in range(l-1,-1,-1):
if(isOperator(prefix[i])):
temp=s.pop()
temp2=temp+s.pop()+prefix[i]
s.push(temp2)
else:
s.push(prefix[i])
return s.peek()
def prefixxer(postfix):
s = Stack()
l = len(postfix)
for i in range(l):
if (isOperator(postfix[i])):
temp = ''
temp2 = ''
temp = s.pop()
temp2 = postfix[i] + s.pop() + temp
s.push(temp2)
else:
s.push(postfix[i])
return s.peek()
def postfix(infix):
#op stack is where we store left parentheses, it will count
#how much we need to pop when we hit a right parenthesis
opstack=Stack()
#output will be the return of all our values
output=[]
#splits up the infix notation equation
input1=list(infix)
#declare a dict
prec={}
#determine the level of precedence for operators
prec['*']=3
prec['/']=3
prec['+']=2
prec['-']=2
prec['(']=1
for i in input1:
#append non operators/ parenthesises into output
if i in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1023456789':
output.append(i)
#if is a left parenthesis, append it to the stack
elif i =='(':
opstack.push(i)
#if it is a right parenthesis,
#pop a left parenthesis out of the stack
elif i==')':
topToken=opstack.pop()
#while the top of the stack is NOT a left parenthesis and
#is an operator, keep on popping that shit into the output
while topToken !="(":
output.append(topToken)
topToken=opstack.pop()
#else if it is an operator
else:
#while the opstack is NOT empty and and the operator's precident in the stack
#is GREATER than the operator currently being iterated on
#pop that operator into the stack
while (not opstack.isEmpty()) and (prec[opstack.peek()]) >=prec[i]:
output.append(opstack.pop())
#otherwise, just push the current operator into the stack
opstack.push(i)
#and this last while loop is to get out the remaining operators at the end
while not opstack.isEmpty():
output.append(opstack.pop())
return " ".join(output)