How to search a Python List via Object Attribute?

Question

Consider the following python class:

class Event(Document):
  name = StringField()
  time = DateField()
  location = GeoPointField()

  def __unicode__(self):
    return self.name

Now I create a list of Events:

x = [Event(name='California Wine Mixer'),
  Event(name='American Civil War'),
  Event(name='Immaculate Conception')]

Now I want to add only unique events by searching via the event name. How is this done with the boolean in syntax?

The following is incorrect:

a = Event(name='California Wine Mixer')
if a.name in x(Event.name):
  x.append(a)

kennytm · Accepted Answer · 2010-11-07 19:22:52Z

3

By unique I think you want something like "if a.name not in x(Event.name):", which can be written as

if not any(y.name == a.name for y in x):
  ...

But if the name acts as an index, it is better to use a dictionary to avoid the O(N) searching time and the more complex interface.

event_list = [Event(name='California Wine Mixer'), ...]

event_dict = dict((b.name, b) for b in event_list)
# ignore event_list from now on.

....

a = Event(name='California Wine Mixer')
event_dict.setdefault(a.name, a)

answered Nov 7, 2010 at 19:22

kennytm

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1 Comment

agentargo Over a year ago

Yeah, that's what I meant. Thanks!

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