Selecting A Single Field From A List Of Dictionaries In Python

Lets say I have a list of dictionaries like so: dictionList = {1: {'Type': 'Cat', 'Legs': 4}, 2: {'Type': 'Dog', 'Legs': 4}, 3: {'Type': 'Bird', 'Legs

Solution 1:

Use the values iterator for dictionaries:

for v in dictionList.values():
    if v['Type']=='Dog':
         print "Found a dog!"

EDIT: I will say though that in your original question you are asking to check the Type of a value in a dictionary, which is somewhat misleading. What you are requesting is the content of a value called 'Type'. This may be a subtle difference to understanding what you want, but it is a rather large difference in terms of programming.

In Python, you should ever only RARELY need to type-check anything.

Solution 2:

Use itervalues() to check your dictionary of dictionaries.

for val in dictionList.itervalues():
   if val['Type'] == 'Dog':
      print 'Dog Found'
      print val

gives:

Dog Found
{'Legs': 4, 'Type': 'Dog'}

no need to use iter/iteritems, simply examine the values.

Solution 3:

>>> diction_list = {1: {'Type': 'Cat', 'Legs': 4},
            2: {'Type': 'Dog', 'Legs': 4},
            3: {'Type': 'Bird', 'Legs': 2}}
>>> any(d['Type'] == 'Dog' for d in diction_list.values())
True

Solution 4:

I think you're just using the wrong syntax...try this:

>>> a = {1: {"Type": "Cat", "Legs": 4}, 2: {"Type": "Dog", "Legs": 4}, 3: {"Type": "Bird", "Legs": 2}}
>>> for item in a:
...     if a[item].get("Type") == "Dog":
...             print "Got it"

Solution 5:

Try

for i in dictionList.itervalues():
    if i['Type'] == "Dog":
        print "Found dog!"

The problem is that, in your example, i is the integer key. With itervalues, you grab the value at the key (aka the dictionary you are wanting to parse).