Common Dictionary Operations in Python

Dictionary

A dictionary constant consists of a series of key-value pairs enclosed by curly braces { }

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With dictionaries, you can store things so that you quickly can find them again

• What is a Dictionary in Python?
• Python Programming – Creation, Initialization and Accessing The Elements In A Dictionary
• Python Programming – Python Dictionary

Dictionary Operations

Below is a list of common dictionary operations:

create an empty dictionary

x = {}

create a three items dictionary

x = {"one":1, "two":2, "three":3}

access an element

x['two']

get a list of all the keys

x.keys()

get a list of all the values

x.values()

add an entry

x["four"]=4

change an entry

x["one"] = "uno"

delete an entry

del x["four"]

make a copy

y = x.copy()

remove all items

x.clear()

number of items

z = len(x)

test if has key

z = x.has_key("one")

looping over keys

for item in x.keys(): print item

looping over values

for item in x.values(): print item

using the if statement to get the values

if "one" in x:
    print x['one']

if "two" not in x:
    print "Two not found"

if "three" in x:
    del x['three']