[Tutor] how to do multiple searching against many lists

[Kent Johnson]

Srinivas Iyyer wrote:
> Hi Group, 
> 
> my Problem:
> 
> I have soms list for variety of animals, birds,
> bacteria
> 
> 
> I have another list:
> search_list =
> ['cat','python','parrot','donkey','e.coli']
> 
> animals = ['cat','tiger','donkey','zebra','lemur']
> birs = ['parrot','mina','oriole','blue jay']
> bacteria =
> ['e.coli','bacillus','staphy','acetobacter']
> 
> my output should look like this:
> 
> cat '\t' animal
> python '\t' animal
> parrot '\t' bird
> donkey '\t'animal
> e.coli '\t' bacteria
> 
> Can I do this using dictionaries , so that to make it
> faster?

I would make animals, birds and bacteria into sets rather than dicts 
since the values don't map to anything. You could store the sets in a 
single dict to give you the name -> set mapping. For example:

  >>> animals = set(['cat','tiger','donkey','zebra','lemur'])
  >>> birds = set(['parrot','mina','oriole','blue jay'])
  >>> bacteria = set(['e.coli','bacillus','staphy','acetobacter'])
  >>> fauna = { 'animals' : animals, 'birds' : birds, 'bacteria' : 
bacteria }
  >>> for item in ['cat','python','parrot','donkey','e.coli']:
  ...   for setName, setValue in fauna.iteritems():
  ...     if item in setValue:
  ...       print '%s\t%s' % (item, setName)
  ...
cat     animals
parrot  birds
donkey  animals
e.coli  bacteria

Or, if each critter can be in only one set, you could make one dict that 
maps the critter name to the set it is in, and just do one lookup:

  >>> fauna2 = {}
  >>> for animal in animals: fauna2[animal] = 'animal'
  ...
  >>> for bird in birds: fauna2[bird] = 'bird'
  ...
  >>> for bacterium in bacteria: fauna2[bacterium] = 'bacteria'
  ...
  >>> for item in ['cat','python','parrot','donkey','e.coli']:
  ...   print '%s\t%s' % (item, fauna2.get(item, 'None'))
  ...
cat     animal
python  None
parrot  bird
donkey  animal
e.coli  bacteria

Kent