macc_200 wrote:
Hi,
just starting programming and have an elementary question after
playing around with lists but cannot find the answer with googling.
I have a list of variables and I would like some of those variables to
be integers and some to be operators so the list would look something
like [5 * 4 - 4 + 6] and then be able to evaluate the result (i.e. get
10). How do you make the interpreter see the operator as that instead
of a string and just echo the list back to me.
Your specification is ambiguous because you mention lists but wrote an
evaluable expression inside of brackets. Others have answered the
question you probably really are asking. For fun, though, I'm going to
pretend you meant "list" and not whatever [5 * 4 - 4 + 6] is:
import operator
opdict = {'+' : operator.add,
'-' : operator.sub,
'*' : operator.mul,
'/' : operator.div}
def take_two(aniterable):
assert len(aniterable) % 2 == 0
aniter = iter(aniterable)
while True:
try:
yield aniter.next(), aniter.next()
except StopIteration:
break
def reductifier(alist):
value = alist.pop(0)
for op, operand in take_two(alist):
value = opdict[op](value, operand)
return value
reductifier([5, "*", 4, "-", 4, "+", 6])
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