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Basic Datatypes: Dictionaries

#############################

aa = {}   # an empty dictionary

dict = {'alpha':3, 'beta':4, 'gamma':5, 'delta':7}

# getting value
print 'beta is:', dict['beta']   # beta is: 4

# add an entry
dict['XXX'] = 10
print dict   # {'alpha': 3, 'beta': 4, 'XXX': 10, 'gamma': 5, 'delta': 7}

# delete an entry
del dict['alpha']
print dict   # {'beta': 4, 'XXX': 10, 'gamma': 5, 'delta': 7}

# print keys, print values
print dict.keys()     # ['beta', 'XXX', 'gamma', 'delta']
print dict.values()   # [4, 10, 5, 7]

# check if an entry is there
print 'beta is there:', dict.has_key('beta')     # True
print 'alpha is there:', dict.has_key('alpha')   # False (it was removed)

# iterate the dict. and access the key/value pairs
myDict = {'alpha':3, 'beta':4, 'gamma':5, 'delta':7}
for k, v in myDict.iteritems():
    print k, v

dict.clear()   # delete all items in the dict.
dict = {}      # another way to delete all items

List comprehension with dictionaries

data = {'location': 'death star', \
        'hero': 'luke skywalker', \
        'objective': 'save princess leia'}

li = ["%s=%s" % (k, v) for (k, v) in data.items()]
print li   # ['objective=save princess leia', 'hero=luke skywalker', 'location=death star']

Some dictionary functions