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Ingy döt Net 2013-10-27 22:24:23 +00:00
parent 6f050a029e
commit 776bba907c
3887 changed files with 59894 additions and 7280 deletions
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42
Task/Parsing-RPN-to-infix-conversion/Python/parsing-rpn-to-infix-conversion.py
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@ -1,5 +1,6 @@
from math import log as ln
from math import sqrt, log, exp, sin, cos, tan, pi, e
from ast import literal_eval
"""
>>> # EXAMPLE USAGE
@ -34,8 +35,6 @@ arity_dict = {'abs':1, 'sqrt':1, 'exp':1, 'log':1, 'ln':1,
class Node:
def __init__(self,x,op,y=None):
global prec_dict,assoc_dict,arity_dict
self.precedence = prec_dict[op]
self.assocright = assoc_dict[op]
self.arity = arity_dict[op]
@ -91,22 +90,16 @@ class Node:
"""
return 'Node(%s,%s,%s)'%(repr(self.x), repr(self.op), repr(self.y))
def __cmp__(self, other):
"""
polymorphic comparisons to determine precedence
>>> Node('3','+','4') < Node('6','*','7') < Node('3','**','4')
True
>>> Node('3','+','4') == Node('6','+','7')
True
>>> Node('3','+','4') == '-'
True
>>> Node('3','**','4') < '1'
True
"""
def __lt__(self, other):
if isinstance(other, Node):
return cmp(self.precedence, other.precedence)
return cmp(self.precedence, prec_dict.get(other,9))
return self.precedence < other.precedence
return self.precedence < prec_dict.get(other,9)
def __gt__(self, other):
if isinstance(other, Node):
return self.precedence > other.precedence
return self.precedence > prec_dict.get(other,9)
def rpn_to_infix(s, VERBOSE=False):
@ -168,8 +161,6 @@ def rpn_to_infix(s, VERBOSE=False):
>>> rpn_to_infix('3 4 2 * 1 -5 - ln 2 3 ** ** / +')
'3 + 4 * 2 / ln(1 + 5) ** 2 ** 3'
"""
global prec_dict, arity_dict
if VERBOSE : print('TOKEN STACK')
stack=[]
@ -203,21 +194,20 @@ def rpn_eval(s):
True
"""
global prec_dict, arity_dict
stack=[]
for token in s.replace('^','**').split():
if token in prec_dict:
if arity_dict[token] == 1:
stack.append(eval('%s(%s)'%(token,stack.pop())))
stack.append(literal_eval('%s(%s)'%(token,stack.pop())))
elif arity_dict[token] == 2:
x,y=stack.pop(),stack.pop()
stack.append(eval('(%s) %s %s'%(y,token,x)))
stack.append(literal_eval('(%s) %s %s'%(y,token,x)))
else:
stack.append(token)
return stack[0]
if __name__ == "__main__":
import doctest
doctest.testmod()
strTest = "3 4 2 * 1 -5 - ln 2 3 ** ** / +"
strResult = rpn_to_infix(strTest)
print ("Input: ",strTest)
print ("Output:",strResult)