Python search by value

Question

I need a proper solution to search for a key in a nested data structures in Python. Lets assume that I have variable with value \'check\' and dict like this:

Answer 1

Standard approach:

for k, v in SERVICES.items(): # or iteritems in Python 2
    if 'check' in v:
        print(k) # 'domain'
        break

If you expect to have multiple keys matching the condition, just remove break.

Functional approach:

>>> next(filter(lambda x: 'check' in SERVICES[x], SERVICES))
'domain'

Answer 2

SERVICES = {
    'domain': ['check','whois','register'],
    'user': ['create','show','delete'],
    'invoice': ['toPdf','print']
}

print [k for k in SERVICES if 'check' in SERVICES[k]]

Answer 3

Simply iterate over the dictionary keys and check if check is one of the values of the value corresponding to the key. If you find it then give it to the next call.

print next(key for key in SERVICES if 'check' in SERVICES[key])
# domain