Question 1

Question 7What are the two ways to add something to a list ? How are they different ?

Accepted Answer

The two methods to add something to a list are:append method — The syntax of append method is list.append(item).extend method — The syntax of extend method is list.extend(<list>).DifferenceThe difference between the append() and extend() methods in python is that append() adds one element at the end of a list, while extend() can add multiple elements, given in the form of a list, to a list.Exampleappend method:lst1 = [10, 12, 14]    
lst1.append(16)  
print(lst1)  Output — [10, 12, 14, 16]extend method:t1 = ['a', 'b', 'c']  
t2 = ['d', 'e']  
t1.extend(t2)  
print(t1)  Output — ['a', 'b', 'c', 'd', 'e']

Question 2

Question 8What are the two ways to remove something from a list? How are they different ?

Accepted Answer

The two ways to remove something from a list are:pop method — The syntax of pop method is List.pop().del statement — The syntax of del statement isdel list[] # to remove element at index del list[:] # to remove elements in list slice DifferenceThe difference between the pop() and del is that pop() method is used to remove single item from the list, not list slices whereas del statement is used to remove an individual item, or to remove all items identified by a slice.Examplepop() method:t1 = ['k', 'a', 'e', 'i', 'p', 'q', 'u'] ele1 = t1.pop(0) print(ele1)Output — 'k'del statement:lst = [1, 2, 3, 4, 5] del lst[2:4] print(lst)Output — [1, 2, 5]

Question 3

Question 19How is del D and del D[<key>] different from one another if D is a dictionary ?

Accepted Answer

del D deletes the entire dictionary D. After executing del D, the variable D is no longer defined, and any attempt to access D will result in a NameError.del D[] deletes the key-value pair associated with the specified key from the dictionary D. After executing del D[], the dictionary D still exists, but the specified key and its corresponding value are removed from the dictionary.For example:d = {1: 'a' , 2 : 'b'} del d[2] print(d) del d print(d)Output{1:'a'} NameError: name 'd' is not defined.

Question 4

Question 20Create a dictionary named D with three entries, for keys 'a', 'b' and 'c'. What happens if you try to index a nonexistent key (D['d']) ? What does python do if you try to assign to a nonexistent key d.(e.g., D['d'] = 'spam') ?

Accepted Answer

In this example, the dictionary D does not contain the key 'd'. Therefore, attempting to access this key by D['d'] results in a KeyError because the key does not exist in the dictionary.If we try to assign a value to a nonexistent key in a dictionary, python will create that key-value pair in the dictionary. In this example, the key 'd' did not previously exist in the dictionary D. When we attempted to assign the value 'spam' to the key 'd', python created a new key-value pair 'd': 'spam' in the dictionary D.D = {'a' : 1, 'b' : 2, 'c' : 3}
D['d'] = 'spam'OutputD = {'a' : 1, 'b' : 2, 'c' : 3, 'd' : 'spam'}

Question 5

Question 21What is sorting ? Name some popular sorting techniques.

Accepted Answer

Sorting refers to arranging elements of a sequence in a specific order — ascending or descending.Sorting Techniques are as follows :Bubble SortInsertion SortSelection SortHeap SortQuick Sort

Question 6

Question 22Discuss Bubble sort and Insertion sort techniques.

Accepted Answer

Bubble Sort :In Bubble sort, the adjoining values are compared and exchanged if they are not in proper order. This process is repeated until the entire array is sorted.Insertion Sort :Insertion sort is a sorting algorithm that builds a sorted list one element at a time from the unsorted list by inserting the element at its correct position in sorted list.

Question 7

Question 1(a)What will be the output produced by following code fragments ?y = str(123)  
x = "hello" \* 3  
print(x, y)  
x = "hello" + "world"  
y = len(x)  
print(y, x)

Accepted Answer

Outputhellohellohello 123
10 helloworld
Explanationstr(123) converts the number 123 to string and stores in y so y becomes "123". "hello" * 3 repeats "hello" 3 times and stores it in x so x becomes "hellohellohello"."hello" + "world" concatenates both the strings so x becomes "helloworld". As "helloworld" contains 10 characters so len(x) returns 10.

Question 8

Question 1(c)What will be the output produced by following code fragments ?x = "hello world"  
print(x[:2], x[:-2], x[-2:])  
print(x[6], x[2:4])  
print(x[2:-3], x[-4:-2])

Accepted Answer

Outputhe hello wor ld
w ll
llo wo or
Explanationprint(x[:2], x[:-2], x[-2:]) —x[:2] extracts the substring from the beginning of x up to index 1, resulting in "he".x[:-2] extracts the substring from the beginning of x up to the third last character, resulting in "hello wor".x[-2:] extracts the substring from the last two characters of x until the end, resulting in "ld".Hence, output of this line becomes he hello wor ldprint(x[6], x[2:4]) —x[6] retrieves the character at index 6, which is 'w'.x[2:4] extracts the substring from index 2 up to index 3, resulting in "ll".Hence, output of this line becomes w llprint(x[2:-3], x[-4:-2]) —x[2:-3] extracts the substring from index 2 up to the fourth last character, resulting in "llo wo".x[-4:-2] extracts the substring from the fourth last character to the third last character, resulting in "or".Hence, output of this line becomes llo wo or

Question 9

Question 2Write a short Python code segment that adds up the lengths of all the words in a list and then prints the average (mean) length.

Accepted Answer

word_list = eval(input("Enter a list of words: "))
total_length = 0
for word in word_list:
    total_length += len(word)
average_length = total_length / len(word_list)
print("Average length of words:", average_length)OutputEnter a list of words: ["apple", "banana", "orange", "kiwi"] 
Average length of words: 5.25
ExplanationThe code prompts the user to enter a list of words and assigns it to the variable word_list.We iterate over word_list using for loop. Inside the loop, length of each word gets added to total_length variable.Average length is calculated by dividing total_length by the number of words in word_list.

Question 10

Question 3Predict the output of the following code snippet ?a = [1, 2, 3, 4, 5] 
print(a[3:0:-1])

Accepted Answer

Output[4, 3, 2]
ExplanationThe slicing notation a[start:stop:step] extracts a portion of the list from index start to stop-1 with a specified step. In the slicing part a[3:0:-1]:start is 3, which corresponds to the element with value 4.stop is 0, but as element at stop index is excluded so slicing goes up to index 1.step is -1, indicating that we want to step backward through the list.Putting it together:a[3:0:-1]This extracts elements from index 3 to (0+1) in reverse order with a step of -1.The output of the code will be:[4, 3, 2]

Question 11

Question 4(a)Predict the output of the following code snippet?arr = [1, 2, 3, 4, 5, 6]
for i in range(1, 6):
    arr[i - 1] = arr[i]
for i in range(0, 6):
    print(arr[i], end = "")

Accepted Answer

Output234566
Explanationarr is initialised as a list with elements [1, 2, 3, 4, 5, 6].for loop iterates over the indices from 1 to 5. For each index i, it assigns the value of arr[i] to arr[i - 1], effectively shifting each element one position to the left. After this loop, the list arr becomes [2, 3, 4, 5, 6, 6].Second for loop iterates over the indices from 0 to 5 and prints each element of the list arr without newline characters because of end="" parameter. Then it prints the elements of the modified list arr, resulting in 234566.

Question 12

Question 6Assuming words is a valid list of words, the program below tries to print the list in reverse. Does it have an error ? If so, why ? (Hint. There are two problems with the code.)for i in range(len(words), 0, -1):
    print(words[i], end=' ')

Accepted Answer

There are two issue in range(len(words), 0, -1):The start index len(words) is invalid for the list words as it will have indexes from 0 to len(words) - 1.The end index being 0 means that the last element of the list is missed as the list will be iterated till index 1 only.The corrected python code is :for i in range(len(words)-1, -1, -1):
    print(words[i], end=' ')

Question 13

Question 7What would be the output of following code if ntpl = ("Hello", "Nita", "How's", "life ?") ?(a, b, c, d) = ntpl 
print("a is:", a) 
print("b is:", b) 
print("c is:", c) 
print("d is:", d) 
ntpl = (a, b, c, d)
print(ntpl[0][0] + ntpl[1][1], ntpl[1])

Accepted Answer

Outputa is: Hello
b is: Nita
c is: How's
d is: life ?
Hi Nita
Explanationntpl is a tuple containing 4 elements. The statement (a, b, c, d) = ntpl unpacks the tuple ntpl into the variables a, b, c, d. After that, the values of the variables are printed.The statement ntpl = (a, b, c, d) forms a tuple with values of variables a, b, c, d and assigns it to ntpl. As these variables were not modified, so effectively ntpl still contains the same values as in the first statement.ntpl[0] ⇒ "Hello"∴ ntpl[0][0] ⇒ "H"ntpl[1] ⇒ "Nita"∴ ntpl[1][1] ⇒"i"ntpl[0][0] and ntpl[1][1] concatenates to form "Hi". Thus ntpl[0][0]+ntpl[1][1], ntpl[1] will return "Hi Nita ".

Question 14

Question 8What will be the output of the following code ?tuple_a = 'a', 'b'  
tuple_b = ('a',  'b')  
print (tuple_a == tuple_b)

Accepted Answer

OutputTrue
ExplanationTuples can be declared with or without parentheses (parentheses are optional). Here, tuple_a is declared without parentheses where as tuple_b is declared with parentheses but both are identical. As both the tuples contain same values so the equality operator ( == ) returns true.

Question 15

Question 9What will be the output of the following code snippet ?rec = {"Name" : "Python", "Age" : "20", "Addr" : "NJ", "Country" : "USA"}
id1 = id(rec)
del rec
rec = {"Name" : "Python", "Age" : "20", "Addr" : "NJ", "Country" : "USA"}
id2 = id(rec)
print(id1 == id2)TrueFalse1Exception

Accepted Answer

OutputTrue
ExplanationIn the given python code snippet, id1 and id2 will point to two different objects in memory as del rec deleted the original dictionary whose id is stored in id1 and created a new dictionary with the same contents storing its id in id2. However, id1 == id2 will compare the contents of the two dictionaries pointed to by id1 and id2. As contents of both the dictionaries are same hence it returns True. If in this code we add another line print(id1 is id2) then this line will print False as id1 and id2 point to two different dictionary objects in memory.

Question 16

Question 10Write the output of the code given below :my_dict = {"name" : "Aman", "age" : 26} 
my_dict['age'] = 27
my_dict['address'] = "Delhi"
print(my_dict.items())

Accepted Answer

Outputdict_items([('name', 'Aman'), ('age', 27), ('address', 'Delhi')])
ExplanationA dictionary my_dict with two key-value pairs, 'name': 'Aman' and 'age': 26 is initialized. Then updates the value associated with the key 'age' to 27. Then adds a new key-value pair 'address': 'Delhi' to the dictionary my_dict. The items() method returns all of the items in the dictionary as a sequence of (key, value) tuples. In this case, it will print [('name', 'Aman'), ('age', 27), ('address', 'Delhi')].

Question 17

Question 11Write a method in python to display the elements of list thrice if it is a number and display the element terminated with '#' if it is not number.For example, if the content of list is as follows :List = ['41', 'DROND', 'GIRIRAJ', '13', 'ZARA']The output should be414141DROND#GIRIRAJ#131313ZAR#

Accepted Answer

def display(my_list):
    for item in my_list:
        if item.isdigit():
            print(item * 3)
        else:
            print(item + '#')
display(my_list = eval(input("Enter the list :")))OutputEnter the elements of the list separated by spaces:41 DROND GIRIRAJ 13 ZARA
414141
DROND#
GIRIRAJ#
131313
ZARA#
ExplanationThe code prompts the user to enter the elements of the list separated by spaces and stores the input as a single string in the variable my_list.Then splits the input string my_list into individual elements and stores them in a new list called new_list.Then for loop iterates over each element in the new_list.The isdigit() method is used to check if all characters in the string are digits. If it's true (i.e., if the element consists only of digits), then it prints the element concatenated with itself three times. Otherwise, if the element contains non-digit characters, it prints the element concatenated with the character '#'.

Question 18

Question 2Write a program that should prompt the user to type some sentence(s) followed by "enter". It should then print the original sentence(s) and the following statistics relating to the sentence(s):Number of wordsNumber of characters (including white-space and punctuation)Percentage of characters that are alpha numericHintsAssume any consecutive sequence of non-blank characters in a word.Solutionstr = input("Enter a few sentences: ")
length = len(str)
spaceCount = 0
alnumCount = 0

for ch in str :
    if ch.isspace() :
        spaceCount += 1
    elif ch.isalnum() :
        alnumCount += 1

alnumPercent = alnumCount / length * 100

print("Original Sentences:")
print(str)

print("Number of words =", (spaceCount + 1))
print("Number of characters =", (length))
print("Alphanumeric Percentage =", alnumPercent)OutputEnter a few sentences: Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands. Its implementation began in December 1989. Python 3.0 was released on 3 December 2008.
Original Sentences:
Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands. Its implementation began in December 1989. Python 3.0 was released on 3 December 2008.
Number of words = 34
Number of characters = 205
Alphanumeric Percentage = 80.48780487804879

Accepted Answer

str=input("Enter a few sentences: ")length=len(str)spaceCount=0alnumCount=0forchinstr:ifch.isspace() :spaceCount+=1elifch.isalnum() :alnumCount+=1alnumPercent=alnumCount/length*100print("Original Sentences:")print(str)print("Number of words =", (spaceCount+1))print("Number of characters =", (length))print("Alphanumeric Percentage =",alnumPercent)OutputEnter a few sentences: Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands. Its implementation began in December 1989. Python 3.0 was released on 3 December 2008.Original Sentences:Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands. Its implementation began in December 1989. Python 3.0 was released on 3 December 2008.Number of words = 34Number of characters = 205Alphanumeric Percentage = 80.48780487804879

Question 19

Question 9Create a dictionary whose keys are month names and whose values are the number of days in the corresponding months.(a) Ask the user to enter a month name and use the dictionary to tell them how many days are in the month.(b) Print out all of the keys in alphabetical order.(c) Print out all of the months with 31 days.(d) Print out the (key-value) pairs sorted by the number of days in each month.Solutiondays_in_months = {
    "january":31,
    "february":28,
    "march":31,
    "april":30,
    "may":31,
    "june":30,
    "july":31,
    "august":31,
    "september":30,
    "october":31,
    "november":30,
    "december":31
}

m = input("Enter name of month: ")

if m not in days_in_months:
    print("Please enter the correct month")
else:
    print("There are", days_in_months[m], "days in", m)

print("Months in alphabetical order are:", sorted(days_in_months))

print("Months with 31 days:", end=" ")
for i in days_in_months:
    if days_in_months[i] == 31:
        print(i, end=" ")

day_month_lst = []
for i in days_in_months:
    day_month_lst.append([days_in_months[i], i])
day_month_lst.sort()

month_day_lst =[]
for i in day_month_lst:
    month_day_lst.append([i[1], i[0]])

sorted_days_in_months = dict(month_day_lst)
print()
print("Months sorted by days:", sorted_days_in_months)OutputEnter name of month: may
There are 31 days in may
Months in alphabetical order are: ['april', 'august', 'december', 'february', 'january', 'july', 'june', 'march', 'may', 'november', 'october', 'september']
Months with 31 days: january march may july august october december
Months sorted by days: {'february': 28, 'april': 30, 'june': 30, 'november': 30, 'september': 30, 'august': 31, 'december': 31, 'january': 31, 'july': 31, 'march': 31, 'may': 31, 'october': 31}

Accepted Answer

days_in_months={"january":31,"february":28,"march":31,"april":30,"may":31,"june":30,"july":31,"august":31,"september":30,"october":31,"november":30,"december":31}m=input("Enter name of month: ")ifmnotindays_in_months:print("Please enter the correct month")else:print("There are",days_in_months[m],"days in",m)print("Months in alphabetical order are:",sorted(days_in_months))print("Months with 31 days:",end=" ")foriindays_in_months:ifdays_in_months[i]==31:print(i,end=" ")day_month_lst=[]foriindays_in_months:day_month_lst.append([days_in_months[i],i])day_month_lst.sort()month_day_lst=[]foriinday_month_lst:month_day_lst.append([i[1],i[0]])sorted_days_in_months=dict(month_day_lst)print()print("Months sorted by days:",sorted_days_in_months)OutputEnter name of month: mayThere are 31 days in mayMonths in alphabetical order are: ['april', 'august', 'december', 'february', 'january', 'july', 'june', 'march', 'may', 'november', 'october', 'september']Months with 31 days: january march may july august october decemberMonths sorted by days: {'february': 28, 'april': 30, 'june': 30, 'november': 30, 'september': 30, 'august': 31, 'december': 31, 'january': 31, 'july': 31, 'march': 31, 'may': 31, 'october': 31}

Question 20

Question 10Write a function called addDict(dict1, dict2) which computes the union of two dictionaries. It should return a new dictionary, with all the items in both its arguments (assumed to be dictionaries). If the same key appears in both arguments, feel free to pick a value from either.Solutiondef addDict(dict1, dict2):
    union_dict = {}
    for key, value in dict1.items():
        union_dict[key] = value
    for key, value in dict2.items():
        union_dict[key] = value
    return union_dict

dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}
result = addDict(dict1, dict2)
print("Union of dict1 and dict2:", result)OutputUnion of dict1 and dict2: {'a': 1, 'b': 3, 'c': 4}

Accepted Answer

defaddDict(dict1,dict2):union_dict={}forkey,valueindict1.items():union_dict[key]=valueforkey,valueindict2.items():union_dict[key]=valuereturnunion_dictdict1={'a':1,'b':2}dict2={'b':3,'c':4}result=addDict(dict1,dict2)print("Union of dict1 and dict2:",result)OutputUnion of dict1 and dict2: {'a': 1, 'b': 3, 'c': 4}

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