Prerequisite: Lists and Tuples
1) What is the output of the following program?
PYTHON
List = [True, 50, 10]
List.insert(2, 5)
print(List, "Sum is: ", sum(List))
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a) [True, 50, 10, 5] Sum is: 66
b) [True, 50, 5, 10] Sum is: 65
c) TypeError: unsupported operand type(s) for +: ‘int’ and ‘str’
d) [True, 50, 5, 10] Sum is: 66
Ans. (d)
Explanation: The List is initially has 3 elements. The insert() adds element 5 at index 2, moving element 10 at index 3 and the List becomes [True, 50, 5, 10]. Boolean has an integer value of 1, thus sum becomes 1 + 50 + 5 + 10 = 66.
2) What is the output of the following program?
PYTHON
T = (1, 2, 3, 4, 5, 6, 7, 8)
print(T[T.index(5)], end = " ")
print(T[T[T[6]-3]-6])
|
a) 4 0
b) 5 8
c) 5 IndexError
d) 4 1
Ans. (b)
Explanation: The inbuilt function index() returns the index of the element. T.index(5) = 4 and T[4] = 5. The other print statement has indexing of tuples, similar to that of Lists. T[6] = 7, T[6]-3 = 4, T[T[6]-3] = 5, T[T[6]-3]-6 = -1 and T[T[T[6]-3]-6], i.e. T[-1] = 8.
3) What is the output of the following program?
PYTHON
L = [1, 3, 5, 7, 9]
print(L.pop(-3), end = ' ')
print(L.remove(L[0]), end = ' ')
print(L)
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a) 5 None [3, 7, 9]
b) 5 1 [3, 7, 9]
c) 5 1 [3, 7, 9]
d) 5 None [1, 3, 7, 9]
Ans. (a)
Explanation: pop() will delete and return the element whose index was passed as parameter. L.pop(-3) will delete 5 and return 5, which is printed by print(). remove() does return any value, it’s a void function. L[0] = 1, L.remove(1) will delete 1 from the list and the list remains to be [3, 7, 9].
4) What is the output of the following program?
PYTHON
def REVERSE(L):
L.reverse()
return(L)
def YKNJS(L):
List = []
List.extend(REVERSE(L))
print(List)
L = [1, 3.1, 5.31, 7.531]
YKNJS(L)
|
a) [1, 3.1, 5.31, 7.531]
b) [7.531, 5.31, 3.1, 1]
c) IndexError
d) AttributeError: ‘NoneType’ object has no attribute ‘REVERSE’
Ans. (b)
Explanation: REVERSE() reverses the list and returns it. YKNJS() adds reverse of a list L to the empty list List. L = [1, 3.1, 5.31, 7.531], gets reversed and becomes [7.531, 5.31, 3.1, 1].
5) What is the output of the following program?
PYTHON
from math import sqrt
L1 = [x**2 for x in range(10)].pop()
L1 + = 19
print(sqrt(L1), end = " ")
L1 = [x**2 for x in reversed(range(10))].pop()
L1 + = 16
print(int(sqrt(L1)))
|
a) 10.0 4.0
b) 4.3588 4
c) 10 .0 4
d) 10.0 0
Ans. (c)
Explanation: The first list compression will create list as [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] and pop() will return 81. 81 + 19 = 100, whose square root is 10.0 and similarly in 2nd case pop() will return 0 due to the reversed range and integer value of square root of 16 is 4.
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