Python -- interview questions

Question 1

Q: How Python is interpreted?

Answer 1

A: Python language is an interpreted language. Python program runs directly from the source code. It converts the source code that is written by the programmer into an intermediate language, which is again translated into machine language that has to be executed.

Question 2

Q: What is the difference between list and tuple?

Answer 2

A: The difference between list and tuple is that the list is mutable while tuple is not. Tuple can be hashed for e.g as a key for dictionaries.

Question 3

Q: How are arguments passed by value or by reference?

Answer 3

A: Everything in Python is an object and all variables hold references to the objects. The references values are according to the functions; as a result, you cannot change the value of the references. However, you can change the objects if it is mutable.

Question 4

Q: What are Dict and List comprehension?

Answer 4

They are syntax constructions to ease the creation of a Dictionary or List based on existing iterable.

Question 5

Q: What are the built-in type does python provides?

Answer 5

A: There are mutable and Immutable types of Pythons built-in types Mutable built-in types
List
Sets
Dictionaries
Immutable built-in types
Strings
Tuples

Question 6

Q: What is namespace in Python?

Answer 6

A: In Python, every name introduced has a place where it lives and can be hooked for. This is known as a namespace. It is like a box where a variable name is mapped to the object placed. Whenever the variable is searched out, this box will be searched, to get the corresponding object.

Question 7

Q: What is lambda in Python?

Answer 7

A: It is a single expression anonymous function often used as an inline function.

Question 8

Q: Why lambda forms in python do not have statements?

Answer 8

A: A lambda form in python does not have statements as it is used to make a new function object and then return them at runtime.

Question 9

Q: What are the generators in Python?

Answer 9

A: The way of implementing iterators are known as generators. It is a normal function except that it yields expression in the function.

Question 10

Q: How can you copy an object in Python?

Answer 10

A: To copy an object in Python, you can try copy.copy () or copy.deepcopy() for the general case. You cannot copy all objects but most of them.

Question 11

Q: What is a negative index in Python?

Answer 11

A: Python sequences can be index in positive and negative numbers. For positive index, 0 is the first index, 1 is the second index and so forth. For negative index, (-1) is the last index and (-2) is the second last index and so forth.

Question 12

Q: How you can convert a number to a string?

Answer 12

A: In order to convert a number into a string, use the inbuilt function str(). If you want an octal or hexadecimal representation, use the inbuilt function oct() or hex().

Question 13

Q: What is the difference between Xrange and range?

Answer 13

A: Xrange returns the xrange object while range returns the list, and uses the same memory and no matter what the range size is.

Question 14

Q: What is the module and package in Python?

Answer 14

A: In Python, the module is the way to structure the program. Each Python program file is a module, which imports other modules like objects and attributes.

Question 15

Q: What are the rules for local and global variables in Python?

Answer 15

Local variables: If a variable is assigned a new value anywhere within the function’s body, it’s assumed to be local.
Global variables: Those variables that are only referenced inside a function are implicitly global.

Question 16

Q: how many Data structures are available In pandas?

Answer 16

A: There are two data structures supported by pandas library, Series and DataFrames. Both of the data structures are built on top of Numpy. Series is a one-dimensional data structure in pandas and DataFrame is the two-dimensional data structure in pandas. There is one more axis label known as Panel which is a three-dimensional data structure and it includes items, major_axis, and minor_axis.

Question 17

Q: What Are A pandas DataFrame? How Will You Create An Empty DataFrame In pandas?

Answer 17

A: Pandas DataFrame is a two-dimensional size-mutable, potentially heterogeneous tabular data structure with labeled axes (rows and columns). It consists of three principal components, the data, rows, and columns. pandas DataFrame can be created from the lists, dictionary, and from a list of the dictionary, etc.
To create an empty DataFrame in pandas, type
import pandas as pd
df = pd.DataFrame()

Question 18

Q:Suppose you want to join train and test dataset (both are two numpy arrays train_set and test_set) into a resulting array (resulting_set) to do data processing on it simultaneously. This is as follows:

Answer 18

A: train_set = np.array([1, 2, 3])
test_set = np.array([[0, 1, 2], [1, 2, 3]])
resulting_set –> [[1, 2, 3], [0, 1, 2], [1, 2, 3]]

Question 19

Q: Can we create a DataFrame with multiple data types in Python? If yes, how can you do it?

Question 20

Q: Write the code to sort an array in NumPy by the nth column?

Answer 20

A: Using argsort () function this can be achieved. If there is an array X and you would like to sort the nth column then code for this will be x[x [: n-1].argsort ()]

Question 21

Q: Explain the usage of decorators?

Answer 21

A: decorator is a function that takes another function and extends the behavior of the latter function without explicitly modifying it. They are used to modify the code in classes and functions. With the help of decorators, a piece of code can be executed before or after the execution of the original code.

Question 22

Q: What is __init__ in Python?

Answer 22

A: __init__ is a reserved method in Python classes which is equivalent to constructors in OOP terminology. The __init__ method is called automatically whenever a new object is initiated. The __init__ method allocates memory for the new object as soon as it is created. This method can also be used to initialize variables.

Question 23

Q: What is self-keyword in Python?

Answer 23

A: Self-keyword is used as the first parameter of a function inside a class that represents the instance of the class. The object or the instance of the class is automatically passed to the method that it belongs to and is received in the ‘self-keyword’. Users can use another name for the first parameter of the function that catches the object of the class, but it is recommended to use the self-keyword only as it is more of a Python convention.

Question 24

What does yield do in python?

Answer 24

yield is an keyword expression used in generators. They suspend the iterator at a certain point and return a value, the generator only goes forward with a next statement.

Co-routines also use this function but use yield from or the variable before it.

Question 25

What is GIL

Answer 25

Global interpreter lock used so only one thread has control (or lock) on the program at a time. https://realpython.com/python-gil/