PYTHON

if key in dictionary python

dict = {"key1": 1, "key2": 2}
if "key1" in dict:
 	print dict["key1]
>> 1

python dictionary contains key

if key in dictionary:
  print(True)

check if dict key contains specific key and value

if (key, value) in d.items():
	print("yes")

python check if key exist in dict

# in tests for the existence of a key in a dict:

d = {"key1": 10, "key2": 23}

if "key1" in d:
    print("this will execute")

if "nonexistent key" in d:
    print("this will not")

# Use dict.get() to provide a default value when the key does not exist:
d = {}

for i in range(10):
    d[i] = d.get(i, 0) + 1

# To provide a default value for every key, either use dict.setdefault() on each assignment:
d = {}

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

# or use defaultdict from the collections module:
from collections import defaultdict

d = defaultdict(int)

for i in range(10):
    d[i] += 1