List: Generally speaking a list is a collection of objects that can contain any types of objects.
It can be an arbitrary mixture of elements like numbers, strings, other lists and so on.
Properties of Python lists:
It can be an arbitrary mixture of elements like numbers, strings, other lists and so on.
Properties of Python lists:
- The contain arbitrary objects like numbers, strings, other lists etc..
- Elements of a list can be accessed by an index
- They are arbitrarily nestable, i.e. they can contain other lists as sublists
- They are mutable, i.e. the elements of a list can be changed
Below are the Example and operations on the list:
import copy
# creating a list itemlist = ['apple','orange','banana','grape']
itemlist_copy = itemlist # To copy a list (This is Shallow copy) #Adding new item to a exiting list
itemlist.append('pepaya') for item in itemlist: print(item)
Output:
apple
orange
banana
grape
pepaya
___________________________________________________________________________________________
# itemlist and itemlist_copy are equal because of Shallow copy print(str(itemlist) +'==>'+str(itemlist_copy))
['apple', 'orange', 'banana', 'grape', 'pepaya']==>['apple', 'orange', 'banana', 'grape', 'pepaya']
# Both lists are refering to the same object id.
print(str(id(itemlist)) + '==>' + str(id((itemlist_copy))))
4334167304==>4334167304
print(itemlist == itemlist_copy)
True print(itemlist is itemlist_copy)
True
# this is deep copy
itemlist_copy = copy.deepcopy(itemlist)
itemlist.append('Avocados')
print(str(itemlist) +'==>'+str(itemlist_copy))
['apple', 'orange', 'banana', 'grape', 'pepaya', 'Avocados']==>
['apple', 'orange', 'banana', 'grape', 'pepaya']
# Both lists are different, refering to different objects
print(str(id(itemlist)) + '==>' + str(id((itemlist_copy))))4334167304==>4334167048# Another way to copy the list is using the list constructor,
as constructor used to create a new object. itemlist_copy = list(itemlist)
# Here it is False because the list reference objects are different.
print("List copy constructor {}".format(itemlist is itemlist_copy)) List copy constructor False
# Here it is True because the list content are same in same order.
print("List copy constructor {}".format(itemlist == itemlist_copy)) List copy constructor True# Both lists are refering to the same object id.print(str(id(itemlist)) + '==>' + str(id((itemlist_copy))))
4334167304==>4334326280# Adding two list even = [2,4,6,8] odd = [1,3,5,7,9] add = even + odd str1 = ['A','B'] str2 = ['C','D','E','FGH']print(sorted(even+odd))
[1, 2, 3, 4, 5, 6, 7, 8, 9]
add.sort()
#It return None, becuase for sorting the values it needs objects and print do not create that
print(add.sort())
None print(add)
[1, 2, 3, 4, 5, 6, 7, 8, 9]
print(str1 + str2)
['A', 'B', 'C', 'D', 'E', 'FGH'] # You can also create a empty list by using the list constructor l1 = [] l2 = list()print("List l1 {}".format(l1))
List l1 [] print("List l2 {}".format(l2))
List l2 []if l1 == l2:print("the list are equal")the list are equal# List constructor automatically create a list when pass a string print(list("This list is created using constructor")) ['T', 'h', 'i', 's', ' ', 'l', 'i', 's', 't', ' ', 'i', 's', ' ', 'c', 'r', 'e', 'a', 't',
'e', 'd', ' ', 'u', 's', 'i', 'n', 'g', ' ', 'c', 'o', 'n', 's', 't', 'r', 'u', 'c', 't',
'o', 'r']
# Nested List even = [2,4,6,8] odd = [1,3,5,7,9] number = [even,odd]
print(number)
[[2, 4, 6, 8], [1, 3, 5, 7, 9]] for list_set in number: print(list_set) # Printing even and odd list for list_evement in list_set: print(list_evement) # Printing even and odd list elements [2, 4, 6, 8] 2 4 6 8 [1, 3, 5, 7, 9] 1 3 5 7 9
