Creating a List

• Lists are created by using a set of square brackets ([])
• Other data types can be type-casted as a list by using its constructor

listExample1 = ["4061CEM", "Programming", "Algorithms"]
listExample2 = list(("4061CEM", "Programming", "Algorithms"))
listExample3 = list("Hello 4061CEM!")

Items of a List

• The items of a list can be any data type
  • i.e. it can be a mixture of data types such as booleans, strings, lists or integers

listExample1 = ["4061CEM", "Programming", "Algorithms"]
listExample2 = [4061, "Programming and Algorithms", True,
                ["Dr Ian Cornelius", "Mr Terry Richards"]]

Accessing List Items (1)

• The items in a list can be accessed by referring to its index number inside a set of square brackets ([])
  • Note that the index of a list begins at 0 in Python, other programming languages begin at 1

listExample1 = ["4061CEM", "Programming", "Algorithms"]
listExample2 = [4061, "Programming and Algorithms", True,
                ["Dr Ian Cornelius", "Mr Terry Richards"]]

listExample1[1]
listExample1[1].upper()
listExample2[3][1]

Accessing List Items (2)

Negative Indexing

• When using a negative index, it will access the list from the end
  • i.e. -1 will refer to the last item and -2 the second to last item etc.

listExample1 = ["4061CEM", "Programming", "Algorithms"]

listExample1[-1]
listExample1[-2]

Accessing List Items (3)

Slicing a List using Positive Indexes i

• A selection of items in a list can be returned using a slice
  • a slice is a number range using a colon (“:”) between the two numbers
  • i.e. 1:3 represents begin at index 1 and go up to index 3
• The search will begin at the start value and include it in the returned list
  • it will end at the end value, but will not include it in the returned list

listExample1 = [4061, "Programming and Algorithms", True, "Dr Ian Cornelius"]

listExample1[1:3]

Accessing List Items (4)

Slicing a List using Positive Indexes ii

• By not providing a start value, the range function will always begin at the first index

listExample1 = [4061, "Programming and Algorithms", True, "Dr Ian Cornelius"]

listExample1[:3]

• If you do not provide an end value, it will return all items from the start index to the end of the list

listExample1[2:]

Modifying a List (1)

• As items are ordered and indexed, they are modifiable; otherwise known as being mutable

Inserting an Item

• Items can be inserted into the list and not replace pre-existing items at a given index using the insert() function

listExample1 = ["4061CEM", "Programming", "Algorithms"]

listExample1.insert(3, "Dr Ian Cornelius")

• You can also insert an item at a different index
  • this will move the item at the index to the right by one, and all other items

listExample1.insert(1, "Dr Ian Cornelius")

Modifying a List (2)

Appending an Item

• Items can be inserted at the end of the list using the append() function

listExample1 = ["4061CEM", "Programming", "Algorithms"]

listExample1.append("Mr Terry Richards")

Modifying a List (3)

Removing Items from a List i

• Items can be removed from a list using the remove() function
• This will search the list for a specific value and then remove it

listExample1 = ["4061CEM", "Programming", "Algorithms"]

listExample1.remove("Programming")

Modifying a List (4)

Removing Items from a List ii

• An item can also be removed from a list by using the pop() function
  • this will remove the item from a list by its index

listExample1 = ["4061CEM", "Programming", "Algorithms"]

listExample1.pop(1)

Modifying a List (5)

Removing Items from a List iii

• An item can also be removed from a list by referring to its index in square brackets ([]) and using the del keyword

listExample1 = ["4061CEM", "Programming", "Algorithms"]

del listExample1[1]

Modifying a List (6)

Clearing a List

• A list can be cleared of all its items, but still reserve its memory location by using the clear() function
• This will empty the contents of a list and leave it empty, symbolised by just the square brackets ([])

listExample1 = ["4061CEM", "Programming", "Algorithms"]

listExample1.clear()

Merging a List (1)

• There are various methods of merging two lists together: concatenation or extension

Concatenating a List

• The items of a list can be concatenated with the items of another list using the + operator

listExample1 = ["4061CEM", "Programming and Algorithms 1", "Dr Ian Cornelius"]
listExample2 = ["4059CEM", "Legal and Ethical Foundations", "Mr Terry Richards"]

mergedListExample1 = listExample1 + listExample2

Merging a List (2)

Extending a List

• The items of a list can be merged with the items of another list using the extend() function

listExample1 = ["4061CEM", "Programming and Algorithms 1", "Dr Ian Cornelius"]
listExample2 = ["4059CEM", "Legal and Ethical Foundations", "Mr Terry Richards"]

listExample1.extend(listExample2)

Copying a List

• The method of copying a list by using list2 = list1 is incorrect
  • this method creates a reference to list1 and not an actual copy; therefore any changes made in list1 will occur in list2
• The correct process of copying a list can be achieved by the copy() function or the list() constructor itself

listExample1 = ["4061CEM", "Programming", "Algorithms"]

copyListExample1 = listExample1.copy()
copyListExample2 = list(listExample1)

Creating a Tuple

• Tuples are created by using a set of brackets (())
• Other data types can be type-casted as a tuple by using its constructor

tupleExample1 = ("4061CEM", "Programming", "Algorithms")
tupleExample2 = tuple("Hello 4061CEM")

Items of a Tuple

• The items of a tuple can be any data type
  • i.e. it can be a mixture of data types such as booleans, strings, tuples or integers

tupleExample1 = ("4061CEM", "Programming", "Algorithms")
tupleExample2 = (4061, "Programming and Algorithms", True,
                    ("Dr Ian Cornelius", "Mr Terry Richards"))

Accessing Tuple Items (1)

• The items in a tuple can be accessed by referring to its index number inside a set of square brackets ([])
  • Note that the index of a tuple begins at 0 in Python, other programming languages begin at 1

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

tupleExample1[1]
tupleExample1[2]

Accessing Tuple Items (2)

Negative Indexing

• When using a negative index, it will access the tuple from the end
  • i.e. -1 will refer to the last item and -2 the second to last item etc.

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

tupleExample1[-1]
tupleExample1[-2]

Accessing Tuple Items (3)

Slicing a Tuple using Positive Indexes i

• A selection of items in a tuple can be returned using a slice
  • a slice is a number range using a colon (“:”) between the two numbers
  • i.e. 1:3 represents begin at index 1 and go up to index 3
• The search will begin at the start value and include it in the returned tuple
  • it will end at the end value, but will not include it in the returned tuple

tupleExample1 = (4061, "Programming and Algorithms", True, "Dr Ian Cornelius")

tupleExample1[1:3]

Accessing Tuple Items (4)

Slicing a Tuple using Positive Indexes ii

• By not providing a start value, the range function will always begin at the first index

tupleExample1 = (4061, "Programming and Algorithms", True, "Dr Ian Cornelius")

tupleExample1[:3]

• By not providing an end value, the range function will always terminate at the last index

tupleExample1[2:]

Modifying a Tuple (1)

• The items of a tuple cannot be changed once they have been created, commonly referred to as immutable
• There is a workaround to changing the items in a tuple:
  1. Convert the tuple to a list
  2. Make the changes as required to the list
  3. Convert the list back to a tuple

tupleExample1 = ("4061CEM", "Programming", "Algorithms")
listExample1 = list(tupleExample1)

listExample1.append("Ian Cornelius")
tupleExample1 = tuple(listExample1)

Modifying a Tuple (2)

Deleting a Tuple

• The entire tuple can be deleted and removed from the memory using the del keyword

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

del tupleExample1

Merging a Tuple

• The items of a tuple can be concatenated with the items of another tuple using the addition (“+”) operator

tupleExample1 = ("4061CEM", "Programming and Algorithms 1", "Dr Ian Cornelius")
tupleExample2 = ("4059CEM", "Legal and Ethical Foundations", "Mr Terry Richards")

mergedTupleExample1 = tupleExample1 + tupleExample2

Multiplying a Tuple

• The items of a tuple can be multiplied to duplicate them, this can be achieved using the multiplying (“*”) operator

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

tupleExample2 = tupleExample1 * 3

Packing and Unpacking a Tuple (1)

• Placing items within a tuple is known as packing
• The items of a tuple can be extracted to their own variable with a process known as unpacking

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

(module_code, title1, title2) = tupleExample1

Packing and Unpacking a Tuple (2)

• When unpacking you must match the number of variables to the number of items in the tuple
• If you have fewer variables than the number of items in the tuple; adding * to the variable name will assign remaining items in the tuple to a list

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

(module_code, *title) = tupleExample1

Packing and Unpacking a Tuple (3)

• If you add the * to a variable that is not last, then Python will assign values to a list for that variable until the number of values left match the number of variables left

tupleExample1 = ("4061CEM", "Programming", "Algorithms", "1", "Dr Ian Cornelius", True)

(module_code, *title, leader, running) = tupleExample1

Count

• The count() method will return the number of times a specified value will occur in the list or tuple

listExample1 = ["4061CEM", "Programming", "Algorithms", "Algorithms", "algorithms"]

listExample1.count('Algorithms')

Index

• The index() method will search the list for a specified value and return its index in the list or tuple

tupleExample1 = ("4061CEM", "Programming", "Algorithms")

tupleExample1.index("Programming")