Python check if value is in a list of dicts

Question

I have a list of dicts e.g.

[{\'name\':\'Bernard\',\'age\':7},{\'name\':\'George\',\'age\':4},{\'name\':\'Reginald\',\'age\':6}]

I\'d like to c

Answer 1

The Proper Solution

There is a much more efficient way to do this than with looping. If you use operators.itemgetter you can do a simple if x in y check

#to simply check if the list of dicts contains the key=>value pair
'George' in map(itemgetter('name'), list_of_dicts)

#if you want to get the index 
index = map(itemgetter('name'), list_of_dicts).index("George") if 'George' in map(itemgetter('name'), list_of_dicts) else None

Answer 2

I think a list comprehension would do the trick here too.

names = [i['name'] for i in l]

Then use it like so:

'Bernard' in names (True)
'Farkle' in names (False)

Or a one liner (If it's only one check)

'Bernard' in [i['name'] for i in l] (True)

Answer 3

No, there cannot be a more efficient way if you have just this list of dicts.

However, if you want to check frequently, you can extract a dictionary with name:age items:

l = [{'name':'Bernard','age':7},{'name':'George','age':4},{'name':'Reginald','age':6}]
d = dict((i['name'], i['age']) for i in l)

now you have d:

{'Bernard': 7, 'George': 4, 'Reginald': 6}

and now you can check:

'Harold' in d   -> False
'George' in d   -> True

It will be much faster than iterating over the original list.

Answer 4

l = [{'name':'Bernard','age':7},{'name':'George','age':4},{'name':'Reginald','age':6}]
search_for = 'George'
print True in map(lambda person: True if person['name'].lower() == search_for.lower() else False, l )

Answer 5

smf = [{'name':'Bernard','age':7},{'name':'George','age':4},{'name':'Reginald','age':6}]
def names(d):
    for i in d:
        for key, value in i.iteritems():
             if key == 'name':
                 yield value


In [5]: 'Bernard' in names(smf)
Out[5]: True


In [6]: 'Bernardadf' in names(smf)
Out[6]: False