Q: 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]
Solution: 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].
Q: 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]
Solution: 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].
Q: 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]
Solution: 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].
Q: 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)]
Solution: 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)].
Q: 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]
Solution: The output of the code shown will be:
(2, -2)
(4, -4)
(6, -6)
This format is due to the statement print(i).
Q: 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]
Solution: 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].
Q: 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]
Solution: The list comprehension to print a list of cube of the numbers for the given list is: [x**3 for x in l].
Q: 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)
Solution: 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]].
Q: 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’]
Solution: 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’].
Q: 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
Solution: 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).