Collection Types:
A collection is an object that represents group of objects.
Advantages of Collection Types:
1) Reduces programming effort
2) Increases programming speed and quality
There are five collection types in python:
1) list 2) tuple 3) set 4) frozenset 5) dict
List:
ØList can be created by using square brackets
ØList can also be created by using list() function
ØList can have homogeneous elements or heterogeneous elements
ØList allows duplicates
ØList supports both positive and negative indexing
ØList supports slice operations also
ØList is mutable
ØList supports deleting an element
ØList is an iterable object
ØElements of a list can be iterated by using for loop or while loop
ØInsertion order is preserved in a list
Examples:
2) List with heterogeneous elements:
3) List with duplicate elements(Indexing & Slicing Operations):
4) Modifying and Deleting elements:
5) Iterating elements of a list by using for loop:
6) Iterating elements of a list by using while loop:
7) List in a list(Nested list):
8) Searching for an element in a list:
9) Unpacking elements from list:
a=[10,20,30]
10) Converting a string into a list:
List comprehensions:
Examples:
1) a=[i for i range(10)]
print(a)
2) a=[i*i for i in range(10,20)]
print(a)
Functions:
1) len() function: It returns the length of the list
2) max() function: It returns the maximum value in a list
3) min() function: It returns the minimum value in a list
4) sum() function: It returns sum of the elements in a list
5) sorted() function: It returns sorted list
Example:
Methods:
1) append() method: It is used append an element at the end of the list.
2) count() method: It is used to count the no. of times appears a specified element in a list.
3) index() method: It is used to get the lowest index of specified element.
4) copy() method: It is used to create a copy of list.
5) remove() method: It is used to remove specified element.
6) extend() method: It is used to extend a list with another list.
7) sort() method: It is used to sort elements in a list.
8) reverse() method: It is used to reverse elements in a list.
9) clear() method: It is used to remove all elements from list.
10) pop() method: It is used to remove an element at the specified index.
11) insert() method: It is used to insert an element at the specified index.
Example:
Tuple:
Ø Tuple can also be created by using tuple() function
Ø Tuple can also be created by assigning multiple values
Ø Tuple can have homogeneous elements or heterogeneous elements
Ø Insertion order is preserved in a tuple
Ø Tuple allows duplicates
Ø Tuple supports both positive and negative indexing
Ø Tuple supports slice operations also
Ø Tuple is immutable
Ø Tuple does not support to delete an element
Ø Tuple can be deleted
Ø Tuple is an iterable object
Tuple Functions:
Methods of Tuple:
Differences between List and Tuple
List Tuple
Set:
Ø Set can also be created by using set() function
Ø {} empty curly braces treated as dict
Ø {10} atleast one element if we write then it will be treated as Set
Ø Set can have homogeneous elements or heterogeneous elements
Ø Set does not allow duplicates
Ø If we write duplicates, automatically ignores
Ø In a set insertion order is not preserved where as in a list and
Ø tuple insertion order is preserved.
Ø Set does not support indexing
Ø Set does not support slice operations
Ø Set is mutable because we can add an element by using add()
method and we can remove an element by using remove() method.
Ø Set is an iterable object
Ø Set in a set is not possible(Nested Set is not possible)
Ø Tuple can be stored in a Set
Ø List cannot be stored in a Set
Ø Set can be stored in a List
Ø Set can be stored in a Tuple
Set Functions:
Set Methods:
Set supports mathematical operations like union, intersection, difference & symmetric difference
1) a|b (or) a.union(b) => Returns a set that has elements from both the sets.
2) a&b (or) a.intersection(b) => Returns a set that has elements which are common in both the sets.
3) a-b (or)a.difference(b) => Returns a set that has elements in a but not in b
4) iv) a^b (or) a.symmetric_difference(b) => Returns a set with elements either in a or in b but not both
Example:
frozenset:
Ø frozenset is a immutable version of a set
Ø frozenset can be created by using frozenset() function
Ø We cannot add an element and we cannot remove an element because frozenset is immutable set
Ø frozenset can be used as a key in a dictionary
Example:
Dict:
Ø Dictionary can also be created by using dict() function
Ø Dictionary maintains data as a key/value pairs
Ø Keys & values are separated with ":" symbol
Ø Here keys are immutable
Ø Here values are mutable
Ø Dictionary does not allow duplicate keys
Ø Values may be duplicated
Ø If we write duplicate keys, automatically ignores
Ø Insertion order is not preserved
Ø Keys & values can be homogeneous or heterogeneous
Ø Dictionary does not support indexing
Ø Dictionary does not support slice operations
Ø Here values can be accessed by using keys
Ø Dictionary is mutable because new key & value pair can be added and existed value can be modified
Ø Dictionary is an iterable object
Ø List cannot be used as a key
Ø List can be used as a value
Ø Tuple can be used as a key
Ø Tuple can be used as a value
Ø Set cannot be used as a key
Ø Set can be used as a value
Dictionary Functions:
Dictionary Methods:
Example:
Iterating Values:
Iterating both keys & values:
Nested dictionary:
Searching a key:
Unpacking key & values from dictionary:
a={101:5000.00, 102:5500.00, 103=6000.00}
Dictionary comprehensions:
A collection is an object that represents group of objects.
Advantages of Collection Types:
1) Reduces programming effort
2) Increases programming speed and quality
1) Reduces programming effort
2) Increases programming speed and quality
There are five collection types in python:
1) list 2) tuple 3) set 4) frozenset 5) dict
1) list 2) tuple 3) set 4) frozenset 5) dict
List:
ØList can be created by using square brackets
ØList can also be created by using list() function
ØList can have homogeneous elements or heterogeneous elements
ØList allows duplicates
ØList supports both positive and negative indexing
ØList supports slice operations also
ØList is mutable
ØList supports deleting an element
ØList is an iterable object
ØElements of a list can be iterated by using for loop or while loop
ØInsertion order is preserved in a list
ØList can be created by using square brackets
ØList can also be created by using list() function
ØList can have homogeneous elements or heterogeneous elements
ØList allows duplicates
ØList supports both positive and negative indexing
ØList supports slice operations also
ØList is mutable
ØList supports deleting an element
ØList is an iterable object
ØElements of a list can be iterated by using for loop or while loop
ØInsertion order is preserved in a list
Examples:
1) List with homogeneous elements:
a=[10,20,15,25,30]
print(a)
print(type(a))
2) List with heterogeneous elements:
a=[10, 10.2, “abc”, True]
print(a)
3) List with duplicate elements(Indexing & Slicing Operations):
a=[10,20,10,50,88,31,89,88]
print(a)
print(a[1])
print(a[-3])
print(a[1:3])
print(a[-4:-1])
4) Modifying and Deleting elements:
a=[10,20,30,13,56,93]
print(a)
a[1]=22
print(a)
del a[2]
print(a)
5) Iterating elements of a list by using for loop:
a=[10,33,63,98,13,67]
for b in a:
print(b)
6) Iterating elements of a list by using while loop:
a=[10, 98, 32, 81, 38, 90]
i=0
while i<len(a):
print(a[i])
7) List in a list(Nested list):
a=[[10,11,12],[20,21,22],[30,31,32]]
for b in a:
print(b)
for c in b:
print(c)
8) Searching for an element in a list:
a=[10, 98, 32, 81, 38, 90]
b=32
if b in a:
print(“Element found”)
else:
print(“Element not found”)
9) Unpacking elements from list:
a=[10,20,30]
b,c,d=a
print(a)
print(b)
print(c)
print(d)
10) Converting a string into a list:
a=”welcome”
b=list(a)
print(a)
List comprehensions:
The concept of generating elements into a list by writing some logic in a list is known as list comprehension.
Examples:
1) a=[i for i range(10)]
1) a=[i for i range(10)]
print(a)
2) a=[i*i for i in range(10,20)]
print(a)
print(a)
Functions:
1) len() function: It returns the length of the list
2) max() function: It returns the maximum value in a list
3) min() function: It returns the minimum value in a list
4) sum() function: It returns sum of the elements in a list
5) sorted() function: It returns sorted list
1) len() function: It returns the length of the list
2) max() function: It returns the maximum value in a list
3) min() function: It returns the minimum value in a list
4) sum() function: It returns sum of the elements in a list
5) sorted() function: It returns sorted list
Example:
a=[10,23,83,43,92,13]
print(len(a))
print(max(a))
print(min(a))
print(sum(a))
print(sorted(a))
Methods:
1) append() method: It is used append an element at the end of the list.
2) count() method: It is used to count the no. of times appears a specified element in a list.
3) index() method: It is used to get the lowest index of specified element.
4) copy() method: It is used to create a copy of list.
5) remove() method: It is used to remove specified element.
6) extend() method: It is used to extend a list with another list.
7) sort() method: It is used to sort elements in a list.
8) reverse() method: It is used to reverse elements in a list.
9) clear() method: It is used to remove all elements from list.
10) pop() method: It is used to remove an element at the specified index.
11) insert() method: It is used to insert an element at the specified index.
1) append() method: It is used append an element at the end of the list.
2) count() method: It is used to count the no. of times appears a specified element in a list.
3) index() method: It is used to get the lowest index of specified element.
4) copy() method: It is used to create a copy of list.
5) remove() method: It is used to remove specified element.
6) extend() method: It is used to extend a list with another list.
7) sort() method: It is used to sort elements in a list.
8) reverse() method: It is used to reverse elements in a list.
9) clear() method: It is used to remove all elements from list.
10) pop() method: It is used to remove an element at the specified index.
11) insert() method: It is used to insert an element at the specified index.
Example:
a=[10,39,53,39,81,35]
print(a)
a.append(33)
print(a)
print(a.count(39))
print(a.index(81))
b=a.copy()
print(b)
a.remove(53)
print(a)
a.extend(b)
print(a)
a.sort()
print(a)
a.reverse()
print(a)
a.pop(2)
print(a)
a.insert(1,91)
print(a)
a.clear()
print(a)
Tuple:
Ø Tuple can be created by using parenthesis
Ø Tuple can also be created by using tuple() function
Ø Tuple can also be created by assigning multiple values
Ø Tuple can have homogeneous elements or heterogeneous elements
Ø Insertion order is preserved in a tuple
Ø Tuple allows duplicates
Ø Tuple supports both positive and negative indexing
Ø Tuple supports slice operations also
Ø Tuple is immutable
Ø Tuple does not support to delete an element
Ø Tuple can be deleted
Ø Tuple is an iterable object
Ø Tuple can also be created by using tuple() function
Ø Tuple can also be created by assigning multiple values
Ø Tuple can have homogeneous elements or heterogeneous elements
Ø Insertion order is preserved in a tuple
Ø Tuple allows duplicates
Ø Tuple supports both positive and negative indexing
Ø Tuple supports slice operations also
Ø Tuple is immutable
Ø Tuple does not support to delete an element
Ø Tuple can be deleted
Ø Tuple is an iterable object
Tuple Functions:
i) len() ii) max() iii) min() iv) sum() v) sorted()
Methods of Tuple:
i) count() ii) index()
Differences between List and Tuple
List Tuple
================== =======================
1) It is mutable 1) It is immutable
2) Deleting an element 2) Deleting an element is not
is possible possible
3) Many methods are 3) Few methods are present
present in a list in a tuple
4) List cannot be used 4) Tuple can be used as a key
as a key in a dict in a dict
Set:
Ø Set can be created by using curly braces
Ø Set can also be created by using set() function
Ø {} empty curly braces treated as dict
Ø {10} atleast one element if we write then it will be treated as Set
Ø Set can have homogeneous elements or heterogeneous elements
Ø Set does not allow duplicates
Ø If we write duplicates, automatically ignores
Ø In a set insertion order is not preserved where as in a list and
Ø tuple insertion order is preserved.
Ø Set does not support indexing
Ø Set does not support slice operations
Ø Set is mutable because we can add an element by using add()
method and we can remove an element by using remove() method.
Ø Set is an iterable object
Ø Set in a set is not possible(Nested Set is not possible)
Ø Tuple can be stored in a Set
Ø List cannot be stored in a Set
Ø Set can be stored in a List
Ø Set can be stored in a Tuple
Ø Set can also be created by using set() function
Ø {} empty curly braces treated as dict
Ø {10} atleast one element if we write then it will be treated as Set
Ø Set can have homogeneous elements or heterogeneous elements
Ø Set does not allow duplicates
Ø If we write duplicates, automatically ignores
Ø In a set insertion order is not preserved where as in a list and
Ø tuple insertion order is preserved.
Ø Set does not support indexing
Ø Set does not support slice operations
Ø Set is mutable because we can add an element by using add()
method and we can remove an element by using remove() method.
Ø Set is an iterable object
Ø Set in a set is not possible(Nested Set is not possible)
Ø Tuple can be stored in a Set
Ø List cannot be stored in a Set
Ø Set can be stored in a List
Ø Set can be stored in a Tuple
Set Functions:
i) len() ii) max() iii) min() iv) sum() v) sorted()
Set Methods:
i) add() ii) remove() iii) clear() iv) copy()
Set supports mathematical operations like union, intersection, difference & symmetric difference
1) a|b (or) a.union(b) => Returns a set that has elements from both the sets.
2) a&b (or) a.intersection(b) => Returns a set that has elements which are common in both the sets.
3) a-b (or)a.difference(b) => Returns a set that has elements in a but not in b
4) iv) a^b (or) a.symmetric_difference(b) => Returns a set with elements either in a or in b but not both
1) a|b (or) a.union(b) => Returns a set that has elements from both the sets.
2) a&b (or) a.intersection(b) => Returns a set that has elements which are common in both the sets.
3) a-b (or)a.difference(b) => Returns a set that has elements in a but not in b
4) iv) a^b (or) a.symmetric_difference(b) => Returns a set with elements either in a or in b but not both
Example:
a={10,20,30,40,50}
b={40,50,60,70,80}
print(a|b)
print(a.union(b)
print(a&b)
print(a.intersection(b))
print(a-b)
print(a.difference(b))
print(a^b)
print(a.symmetric_difference(b))
frozenset:
Ø frozenset is a immutable version of a set
Ø frozenset can be created by using frozenset() function
Ø We cannot add an element and we cannot remove an element because frozenset is immutable set
Ø frozenset can be used as a key in a dictionary
Ø frozenset can be created by using frozenset() function
Ø We cannot add an element and we cannot remove an element because frozenset is immutable set
Ø frozenset can be used as a key in a dictionary
Example:
a={10,20,30,40,50}
b=frozenset(a)
print(a)
print(type(a))
print(b)
print(type(b)
a.add(83)
print(a)
b.add(83) =>Error, because immutable set
print(b)
Dict:
Ø Dictionary can be created by using curly braces
Ø Dictionary can also be created by using dict() function
Ø Dictionary maintains data as a key/value pairs
Ø Keys & values are separated with ":" symbol
Ø Here keys are immutable
Ø Here values are mutable
Ø Dictionary does not allow duplicate keys
Ø Values may be duplicated
Ø If we write duplicate keys, automatically ignores
Ø Insertion order is not preserved
Ø Keys & values can be homogeneous or heterogeneous
Ø Dictionary does not support indexing
Ø Dictionary does not support slice operations
Ø Here values can be accessed by using keys
Ø Dictionary is mutable because new key & value pair can be added and existed value can be modified
Ø Dictionary is an iterable object
Ø List cannot be used as a key
Ø List can be used as a value
Ø Tuple can be used as a key
Ø Tuple can be used as a value
Ø Set cannot be used as a key
Ø Set can be used as a value
Ø Dictionary can also be created by using dict() function
Ø Dictionary maintains data as a key/value pairs
Ø Keys & values are separated with ":" symbol
Ø Here keys are immutable
Ø Here values are mutable
Ø Dictionary does not allow duplicate keys
Ø Values may be duplicated
Ø If we write duplicate keys, automatically ignores
Ø Insertion order is not preserved
Ø Keys & values can be homogeneous or heterogeneous
Ø Dictionary does not support indexing
Ø Dictionary does not support slice operations
Ø Here values can be accessed by using keys
Ø Dictionary is mutable because new key & value pair can be added and existed value can be modified
Ø Dictionary is an iterable object
Ø List cannot be used as a key
Ø List can be used as a value
Ø Tuple can be used as a key
Ø Tuple can be used as a value
Ø Set cannot be used as a key
Ø Set can be used as a value
Dictionary Functions:
i) len() ii) max() iii) min() iv) sum() v) sorted()
Dictionary Methods:
i) copy() ii) clear() iii) items() iv) keys() v) values() vi) get(key)
Example:
a={101:5000.00, 102:5500.00, 103=6000.00}
print(a)
a[104]=9000.00
print(a)
print(a[103])
Iterating keys:
a={101:5000.00, 102:5500.00, 103=6000.00}
for i in a:
print(i)
Iterating Values:
a={101:5000.00, 102:5500.00, 103=6000.00}
for i in a.values():
print(i)
Iterating both keys & values:
a={101:5000.00, 102:5500.00, 103=6000.00}
for i in a.items():
print(i)
Nested dictionary:
a={“venkatesh”:{“C”:99, “Java”:88, “Python”:90}}
print(a)
Searching a key:
a={101:5000.00, 102:5500.00, 103=6000.00}
b=102
if b in a:
print(“Given key present in a dictionary”)
else:
print(“Given key not present in a dictionary”)
Unpacking key & values from dictionary:
a={101:5000.00, 102:5500.00, 103=6000.00}
b,c,d=a.items()
print(b)
print(c)
print(d)
Dictionary comprehensions:
a={i:i*i for i in range(10)}
print(a)