Python

Question 1

How do you type cast in Python?

Answer 1

desired_type(x)
ex: int(5.0)

Question 2

What are the operators for division vs integer division?

Answer 2

/ - division
// - integer division

Question 3

What is the method to insert a value at the end of a list in Python?

Answer 3

list.append(value)

Question 4

The range method has the format range(start, stop, step); what does the following iterate through? range(2, 12, 2)

Answer 4

2, 4, 6, 8, 10

Question 5

What is the structure of a List Comprehension in Python?

Answer 5

List_Name = [(expression(variable)) for (variable) in (List) if (condition)]

Question 6

What does the following List Comprehension code yield?

newList = [x**2 for x in range(6) if x%2==0]
print(newList)

Answer 6

[0, 4, 16]

Question 7

Python List Slicing; what does the following code produce?

values = [x for x in range(11)]
print(values)
print(values[1:3])
print(values[2:-1])
print(values[:2])
print(values[2:])
print(values[::2])

Answer 7

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[1, 2]
[2, 3, 4, 5, 6, 7, 8, 9]
[0, 1]
[2, 3, 4, 5, 6, 7, 8, 9, 10]
[0, 2, 4, 6, 8, 10]

Question 8

In Python are lists passed in functions passed by Value or by Reference?

Answer 8

Pass by Reference

Question 9

What is Pass by Reference?

Answer 9

Reference to variable is passed, allowing direct modification

Question 10

What is Pass by Value

Answer 10

A copy of a variable is passed, so modification does not persist outside of local scope.

Question 11

How is Function Documentation formatted?

Answer 11

’'’Message … ‘’’

Question 12

In Python, how do you import a library with an alias?

Answer 12

import “library” as “alias”

Question 13

In Python, what is the difference between (5,) and (5)

Answer 13

(5,) is a tuple, while (5) is just the int 5

Question 14

What is the NumPy function to find the norm of an Array?

Answer 14

np.linalg.norm(np.array([v1, v2,…, vk]))

Question 15

What is the NumPy function for calculating the dot product of two vectors?

Answer 15

np.dot(np.array([v1,v2,…,vk]),np.array([u1,u2,…,uk]))

Question 16

What is the java equivalent of ‘self’?

Answer 16

‘this’

Question 17

What is the __init__ function’s java equivalent?

Answer 17

A class constructor

Question 18

What is the benefit of opening a file using a ‘with’ statement?

Answer 18

It automatically closes the file afterwards.

Question 19

Given the file data.csv, how would you open it with a ‘with’ statment?

Answer 19

with open(data.csv) as var:

Question 20

what is the python version of a try-catch block?

Answer 20

try:
except:

Question 21

Given an open file stored in variable data_file, how would you read lines via a for loop?

Answer 21

for line in data_file:

Question 22

What does “for line in data_file” return?

Answer 22

a string of a line from the file data_file.

Question 23

Given the function open(“file_name”, mode = ?), what are the options for mode?

Answer 23

“r”: read only
“w”: write. Create if not found
“a”: append. Create if not found
“x”: create