Existing key in Python

Question

How do we check if a given key already exists in a dictionary?

I wrote the following code:

if 'key1' in dict.keys():
  print "Hey"
else:
  print "hello"

but this doesn't seem to be the best way to find an existing key. is there any other way?

Answer 1

The intended way to check for the existence of a key in a dictionary is to use in, such as :

d = dict()

for i in xrange(100):
    key = i % 10
    if key in d:
        d[key] += 1
    else:
        d[key] = 1

for a default value you can use dict.get() as such:

d = dict()

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