Python: Data Types

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set


frozenset

fruits = {"Apple", "Banana", "Cherry", "Apple", "Kiwi"}
basket = frozenset(fruits)

print('Unique elements:', basket)

# Add new fruit throws an error!
basket.add("Orange")
print('After adding new element:', basket)

# AttributeError: 'frozenset' object has no attribute 'add'

frozenset is immutable data type and can't add new element


set

fruits = {"Apple", "Banana", "Cherry", "Apple", "Kiwi"}

print('Unique elements:', fruits)

# Add new fruit
fruits.add("Orange")
print('After adding new element:', fruits)

# Size of the set
print('Size of the set:', len(fruits))

>> Size of the set: 7

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sequence

  • tuple is immutable, list is mutable
  • tuple is faster and consume less memory than list
  • should not define a list in tuple
  • use array to constraint the type of elements stored in the list

tuple

# code to test that tuples are immutable

tuple = (0, 1, 2, 3)
tuple[0] = 4
print(tuple)

# TypeError: 'tuple' object does not support item assignment

tuple is immutable data type and can't add new element


list

# Creating a List with
# the use of Numbers
# code to test that tuples are mutable
List = [1, 2, 4, 4, 3, 3, 3, 6, 5]
print("Original list ", List)

List[3] = 77
print("Example to show mutablity ", List)

# Original list  [1, 2, 4, 4, 3, 3, 3, 6, 5]
# Example to show mutablity  [1, 2, 4, 77, 3, 3, 3, 6, 5]

array

# importing "array" for array creations
import array as arr

# creating an array with integer type
a = arr.array('i', [1, 2, 3])

# creating an array with double type
b = arr.array('d', [2.5, 3.2, 3.3])

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mapping

  • OrderedDict is a subclass of dict object
  • it maintains the orders of keys as inserted

dict

#Create normal dict
my_dict = {}
my_dict['AA'] = 11
my_dict['BB'] = 22
my_dict['CC'] = 33
my_dict['DD'] = 44

for item in my_dict.items():
   print(item)

# ('AA', 11)
# ('CC', 33)
# ('BB', 22)
# ('DD', 44)

OrderedDict

import collections

#Create ordered dict
my_ord_dict = collections.OrderedDict()
my_ord_dict['AA'] = 11
my_ord_dict['BB'] = 22
my_ord_dict['CC'] = 33
my_ord_dict['DD'] = 44

for item in my_ord_dict.items():
   print(item)

# ('AA', 11)
# ('BB', 22)
# ('CC', 33)
# ('DD', 44)

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