Usekey in my_dictdirectly instead ofkey in my_dict.keys():

if 'key1' in my_dict: print("blah") else: print("boo")

This willbe fasterbecause it uses an O(1) hash of the dictionary instead of performing an O(n) linear search of the list of keys.

inTest whether the key exists indict:

d = {"key1": 10, "key2": 23} if "key1" in d: print("this will execute") if "nonexistent key" in d: print("this will not")

---

Usingdict.get()Provides a default value when the key does not exist:

d = {} for i in range(100): key = i % 10 d[key] = d.get(key, 0) + 1

---

To provide a default value foreachkey, usedict.setdefault()on each job:

d = {} for i in range(100): d[i % 10] = d.setdefault(i % 10, 0) + 1

...or better yet, usedefaultdictfrom thecollectionsmodule:

from collections import defaultdict d = defaultdict(int) for i in range(100): d[i % 10] += 1