在python中检查字典键的好方法是什么？

Question

I have a loop that over some values. I have a dictionary that it's keys are in the values of the loop iteration.

I can't change the outer loop.

for i in range(1, 1000000000000):
    if i in my_dict.keys():
        func()

other_func(i)

Each element in: my_dict.keys() appears in range(1, 1000000000000) . However the number of elements in my_dict.keys() is much smaller than the number of iterations.

The problem is that each if check is time consuming. What is a good way of handling this?

Answer 1

I think you can do something like this:

for i in my_dict:
   if 0 < i < 1000000000000:
       func()

range(1, 1000000000000) will generate a list of numbers from 1 to 999999999999 and you just need to check if your key is in that range. So you don't really need to generate the list using range itself.

Answer 2

Change your for loop. See below script.

for key in my_dict.keys():
    if 0 < int(key) < 1000000000000:
        func()

Change for loop because in original implementation for loop would iterate at most 1000000000000 times. But now it will iterate maximum of length of my_dict.

Answer 3

Well, try and except is a good way to go.

for i in range(1, 100000000):
    try:
        my_dict[i]
    except KeyError:
        continue
    func()

If i is not in the keys , then it will throw KeyError and will go to the next iteration. If i is proper key then the func() will be called.

Answer 4

The most simplest way is ,

if my_dict.has_key('key'):