What is Python Dictionary data type
What is Python Dictionary data type
Python dictionary data type gives us a way to store key and value pair. The key and value pair is separated by colon and the key-value item is separated by comma.
The key of a dictionary can be any immutable data types, such as numbers, real numbers, strings and tuples.
The syntax of creating dictionary.
phonebook = {'Alice': '2341', 'Beth': '9102', 'Cecil': '3258'}
The code above creates a dictionary. It has three key-value pairs.
We can also use dictionary to create one to many map.
letterDict = {'vowel':['a','e','i','o','u'],'consonant':['b','c','d','f']}
To loop over the keys of a dictionary, you can use a plain for statement.
d = {'x': 1, 'y': 2, 'z': 3}
# from w w w. ja va 2 s . c o m
for key in d:
print key, 'corresponds to', d[key]
The code above generates the following result.
You can use the dict function to construct dictionaries from other mappings or from sequences of (key, value) pairs:
items = [('name', 'Gumby'), ('age', 42)]
d = dict(items)
print d
print d['name']
The code above generates the following result.
It can also be used with keyword arguments, as follows:
d = dict(name='Gumby', age=42)
print d
The code above generates the following result.
An empty dictionary can be created by {}
.
x = {}
x[42] = 'Foobar'
print x
The code above generates the following result.
Dictionary assignment
dict1 = {'A': 'earth', 'B': 80}
dict1['A'] = 'venus'
dict1['B'] = 6969
dict1['C'] = 'sunos5'
# from w w w . j ava2 s.c om
print dict1
The code above generates the following result.
Dictionary Keys Are Case-Sensitive
d = {} # from ww w. java2s . c o m
d["key"] = "value"
d["key"] = "other value"
print d
d["Key"] = "third value"
print d
The code above generates the following result.