Chapter 7.5, Problem 18CP

1. a.

Explanation of Solution

List method “index()”:

• • “index()” method in Python finds an element in the list and outputs the element’s index.
• • This method is useful in finding the position of the given element in the list.
• • The “index()” method takes an element as an input and searches the list for that element appearance and outputs its position.
• • If more than one occurrence of the element is present in the list, then the method outputs the lowest index.
• • If the element is not present in the list, then this method raises a “ValueError” exception.

Syntax:

In Python, “index()” has the following syntax,

element_index = List_name.index(element)

Explanation:

In the above code,

• • The variable “element_index” stores the return value from the “insert()” method.
• • The variable “List_name” represents the name of the list.
• • The variable “element” indicates the element that is going to be searched in the list.

Example program:

Consider the following example that demonstrates the “index()” method...

1. b.

Explanation of Solution

List method “insert()”:

• • The “insert()” method in Python adds an element to the list.
• • This method places an element in the list at a given index.
• • This method takes an element and its position as input parameters and places the given element at the indicated position.
• • When the element is inserted in the list, the list size is increased to hold the given element.
• • The element at the current index and the elements following it are moved by one place to the list end.
• • This method never throws an exception even if the index is not a valid value.
• • If the index value that is greater than the list size is specified as element’s position, then this method inserts the element at the list end.
• • If the index value is negative and it indicates an invalid position, then this method places the element at the list beginning.

Syntax:

In Python, “insert()” has the following syntax,

List_name.insert(element_index, element)

Explanation:

In the above code,

• • The variable “List_name” represents the name of the list.
• • The variable “element_index” indicates the position where the “element” to be inserted in the list.
• • The variable “element” indicates the element that is going to be inserted in the list.

Example program:

Consider the following example that demonstrates the “insert()” method...

1. c.

Explanation of Solution

List method “sort()”:

• • “sort()” method sorts the list elements.
• • This method arranges the elements in the list in the ascending order.
• • So that the elements in the list are arranged from lower to higher values.
• • This method does not receive any input and does not return a value.

Syntax:

In Python, “sort()” has the following syntax,

List_name.sort()

Explanation:

In the above code,

• • The variable “List_name” represents the list name that is to be sorted.

Example program:

Consider the following example that demonstrates the “sort()” method.

#Function definition

def main():

         #Create a list to store the names

         mynames_list = ['John', 'Tom', 'David', 'Kim']

         #Print message to the user

       ;&#x...

1. d.

Explanation of Solution

List method “reverse()”:

• • “reverse()” method reverses the list elements.
• • This method changes the elements’ orders in the list.
• • So that the list contains the elements in reverse order.
• • This method does not obtain any input and does not output a value.

Syntax:

In Python, “reverse()” has the following syntax,

List_name.reverse()

Explanation:

In the above code,

• • The variable “List_name” represents the list name that is to be reversed.

Example program:

Consider the following example that demonstrates the “reverse()” method.

#Function definition

def main():

         #Create a list to store the numbers

         mynumbers_list = [1, 15, 11, 21, 12]

         #Print message to the user

         print('The numbers list before r...