# Python MCQs on List Comprehension: SET 2

11. What will be the output of the following Python code?

l=[1,2,3,4,5]

[x&1 for x in l]

a) [1, 1, 1, 1, 1]

b) [1, 0, 1, 0, 1]

c) [1, 0, 0, 0, 0]

d) [0, 1, 0, 1, 0]

In the code shown above, each of the numbers of the list, that is, 1, 2, 3, 4 and 5 are AND-ed with 1 and the result is printed in the form of a list. Hence the output is [1, 0, 1, 0, 1].

12. What will be the output of the following Python code?

l1=[1,2,3]

l2=[4,5,6]

[x*y for x in l1 for y in l2]

a) [4, 8, 12, 5, 10, 15, 6, 12, 18]

b) [4, 10, 18]

c) [4, 5, 6, 8, 10, 12, 12, 15, 18]

d) [18, 12, 6, 15, 10, 5, 12, 8, 4]

The code shown above returns x*y, where x belongs to the list l1 and y belongs to the list l2. Therefore, the output is: [4, 5, 6, 8, 10, 12, 12, 15, 18].

13. Write the list comprehension to pick out only negative integers from a given list ‘l’.

a) [x<0 in l]

b) [x for x<0 in l]

c) [x in l for x<0]

d) [x for x in l if x<0]

To pick out only the negative numbers from a given list ‘l’, the correct list comprehension statement would be: [x for x in l if x<0].

For example if we have a list l=[-65, 2, 7, -99, -4, 3] >>> [x for x in l if x<0] The output would be: [-65, -99, -4].

14. What will be the output of the following Python code?

s=[“pune”, “mumbai”, “delhi”]

[(w.upper(), len(w)) for w in s]

a) Error

b) [‘PUNE’, 4, ‘MUMBAI’, 6, ‘DELHI’, 5]

c) [PUNE, 4, MUMBAI, 6, DELHI, 5]

d) [(‘PUNE’, 4), (‘MUMBAI’, 6), (‘DELHI’, 5)]

If we need to generate two results, we need to put it in the form of a tuple. The code shown above returns each word of list in uppercase, along with the length of the word. Hence the output of the code is: [(‘PUNE’, 4), (‘MUMBAI’, 6), (‘DELHI’, 5)].

15. What will be the output of the following Python code?

l1=[2,4,6]

l2=[-2,-4,-6]

for i in zip(l1, l2):

print(i)

a)

2, -2
4, -4
6, -6

b) [(2, -2), (4, -4), (6, -6)]

c)

(2, -2)
(4, -4)
(6, -6)

d) [-4, -16, -36]

The output of the code shown will be:
(2, -2)
(4, -4)
(6, -6)
This format is due to the statement print(i).

16. What will be the output of the following Python code?

l1=[10, 20, 30]

l2=[-10, -20, -30]

l3=[x+y for x, y in zip(l1, l2)]

l3

a) Error

b) 0

c) [-20, -60, -80]

d) [0, 0, 0]

The code shown above returns x+y, for x belonging to the list l1 and y belonging to the list l2. That is, l3=[10-10, 20-20, 30-20], which is, [0, 0, 0].

17. Write a list comprehension for number and its cube for l=[1, 2, 3, 4, 5, 6, 7, 8, 9].

a) [x**3 for x in l]

b) [x^3 for x in l]

c) [x**3 in l]

d) [x^3 in l]

The list comprehension to print a list of cube of the numbers for the given list is: [x**3 for x in l].

18. What will be the output of the following Python code?

l=[[1 ,2, 3], [4, 5, 6], [7, 8, 9]]

[[row[i] for row in l] for i in range(3)]

a) Error

b) [[1, 4, 7], [2, 5, 8], [3, 6, 9]]

c)

1 4 7
2 5 8
3 6 9

d)

(1 4 7)
(2 5 8)
(3 6 9)

In the code shown above, ‘3’ is the index of the list. Had we used a number greater than 3, it would result in an error. The output of this code is: [[1, 4, 7], [2, 5, 8], [3, 6, 9]].

19. What will be the output of the following Python code?

import math

[str(round(math.pi)) for i in range (1, 6)]

a) [‘3’, ‘3’, ‘3’, ‘3’, ‘3’, ‘3’]

b) [‘3.1’, ‘3.14’, ‘3.142’, ‘3.1416’, ‘3.14159’, ‘3.141582’]

c) [‘3’, ‘3’, ‘3’, ‘3’, ‘3’]

d) [‘3.1’, ‘3.14’, ‘3.142’, ‘3.1416’, ‘3.14159’]

The list comprehension shown above rounds off pi(3.141) and returns its value, that is 3. This is done 5 times. Hence the output is: [‘3’, ‘3’, ‘3’, ‘3’, ‘3’].

20. What will be the output of the following Python code?

l1=[1,2,3]

l2=[4,5,6]

l3=[7,8,9]

for x, y, z in zip(l1, l2, l3):

print(x, y, z)

a)

1 4 7
2 5 8
3 6 9

b)

(1 4 7)
(2 5 8)
(3 6 9)

c) [(1, 4, 7), (2, 5, 8), (3, 6, 9)]

d) Error

The output of the code shown above is:
1 4 7
2 5 8
3 6 9
This is due to the statement: print(x, y,z).

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