Python check that key is defined in dictionary [duplicate]

Answer 1

a = {'foo': 1, 'bar': 2}
if a.has_key('foo'):
    a['foo']+=1
else:
    a['foo']=1

Answer 2

parsedData=[]
dataRow={}
if not any(d['url'] == dataRow['url'] for d in self.parsedData):
       self.parsedData.append(dataRow)

Answer 3

Its syntax is if key in dict: :

if "b" in a:
    a["b"] += 1
else:
    a["b"] = 1

Now you may want to look at collections.defaultdict and (for the above case) collections.Counter.

Answer 4

if b in a:
     a[b]+=1
else:
    a[b]=1

Answer 5

Use the in operator:

if b in a:

Demo:

>>> a = {'foo': 1, 'bar': 2}
>>> 'foo' in a
True
>>> 'spam' in a
False

You really want to start reading the Python tutorial, the section on dictionaries covers this very subject.