Dictionaries

Official Documentation

• Dictionaries associates keys with values
• Keys must be immutable (e.g. no lists, but tuples are ok)

Creation

# Literal
d = { key1 => value1, key2 => value2 }

# From list of pairs
d = dict([ (key1, value1), (key2, value2) ])

Operations

Syntax	Semantics
xs[k]	Read value associated with k
xs[k] = v	Add/overwrite value associated with k
len(d)	Number of key/value pairs in d
d.keys()	List of keys
d.values()	List of values
d.items()	Sequence of key/value pairs
del(d[k])	Removes key/value pair whose key is k
d.clear()	Empty dictionary
d.copy()	Make a copy
k in d	Checks if k is a key in d