Top Most Python Interview Questions.pdf

1. What is the difference between list and Tuples in Python?
2. What are the key features of Python?
Answer :-
Python is an interpreted language. That means that, unlike languages like C and its variants,
Python does not need to be compiled before it is run. Other interpreted languages include PHP and
Ruby.
Python is dynamically typed, which means that you don’t need to state the types of variables
when you declare them or anything like that. You can do things like x=111 and then x="I'm a string"
without error
Python is well suited to object-orientated programming in that it allows the definition of classes
along with composition and inheritance. Python does not have access specifiers (like C++’s public,
private).
In Python, functions are first-class objects. This means that they can be assigned to variables,
returned from other functions and passed into functions. Classes are also first class objects
Writing Python code is quick but running it is often slower than compiled languages. Fortunately
Python allows the inclusion of C-based extensions so bottlenecks can be optimized away and often
are. The numpy package is a good example of this, it’s really quite quick because a lot of the
number-crunching it does isn’t actually done by Python
Python finds use in many spheres – web applications, automation, scientific modeling, big data
applications and many more. It’s also often used as “glue” code to get other languages and
components to play nice. Learn more about Big Data and its applications from the Data Engineering
Training.
LIST TUPLES
Lists are mutable i.e they can be
edited.
Tuples are immutable (tuples are lists which can’t
be edited).
Lists are slower than tuples. Tuples are faster than list.
Syntax: list_1 = [10, ‘Chelsea’, 20] Syntax: tup_1 = (10, ‘Chelsea’ , 20)
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Top Most Python Interview Questions

3. What type of language is python? Programming or scripting?
Python is capable of scripting, but in general sense, it is considered as a general-purpose
programming language. To know more about Scripting.
4. Python an interpreted language. Explain.
An interpreted language is any programming language that is not in machine-level code before
runtime. Therefore, Python is an interpreted language.
5. What is pep 8?
PEP stands for Python Enhancement Proposal. It is a set of rules that specify how to format
Python code for maximum readability.
6. What are the benefits of using Python?
The benefits of using python are-
Easy to use– Python is a high-level programming language that is easy to use, read, write and
learn.
Interpreted language– Since python is interpreted language, it executes the code line by line and
stops if an error occurs in any line.
Dynamically typed– the developer does not assign data types to variables at the time of coding.
It automatically gets assigned during execution.
Free and open-source– Python is free to use and distribute. It is open source.
Extensive support for libraries– Python has vast libraries that contain almost any function
needed. It also further provides the facility to import other packages using Python Package
Manager(pip).
Portable– Python programs can run on any platform without requiring any change.
The data structures used in python are user friendly.
It provides more functionality with less coding.
9. What are Dict and List comprehensions?
Dictionary and list comprehensions are just another concise way to define dictionaries and lists.
Example of list comprehension is-
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4
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x=[i for i in range(5)]
The above code creates a list as below-
4
[0,1,2,3,4]
Example of dictionary comprehension is
-
x=[i : i+2 for i in range(5)]
The above code creates a list as below-
[0: 2, 1: 3, 2: 4, 3: 5, 4: 6]
10. What are the common built-in data types in Python?
The common built-in data types in python are-
Numbers– They include integers, floating-point numbers, and complex numbers. eg. 1, 7.9,3+4i
List– An ordered sequence of items is called a list. The elements of a list may belong to
different data types. Eg. [5,’market’,2.4]
Tuple– It is also an ordered sequence of elements. Unlike lists , tuples are immutable, which
means they can’t be changed. Eg. (3,’tool’,1)
String– A sequence of characters is called a string. They are declared within single or double-
quotes. Eg. “Sana”, ‘She is going to the market’, etc.
Set– Sets are a collection of unique items that are not in order. Eg. {7,6,8}
Dictionary– A dictionary stores values in key and value pairs where each value can be accessed
through its key. The order of items is not important. Eg. {1:’apple’,2:’mango}
Boolean– There are 2 boolean values- True and False.
11. What is the difference between .py and .pyc files?
The .py files are the python source code files. While the .pyc files contain the bytecode of the
python files. .pyc files are created when the code is imported from some other source. The
interpreter converts the source .py files to .pyc files which helps by saving time.
12. What is slicing in Python?
Slicing is used to access parts of sequences like lists, tuples, and strings. The syntax of slicing
is-[start:end:step]. The step can be omitted as well. When we write [start:end] this returns all
the elements of the sequence from the start (inclusive) till the end-1 element. If the start or end
element is negative i, it means the ith element from the end. The step indicates the jump or how
many elements have to be skipped. Eg. if there is a list- [1,2,3,4,5,6,7,8]. Then [-1:2:2] will return
elements starting from the last element till the third element by printing every second
element.i.e. [8,6,4].

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13. What are Keywords in Python?
Ans: Keywords in python are reserved words that have special meaning.They are generally used to
define type of variables. Keywords cannot be used for variable or function names. There are
following 33 keywords in python-
14. What are Literals in Python and explain about different Literals
A literal in python source code represents a fixed value for primitive data types. There are 5 types
of literals in python-
String literals– A string literal is created by assigning some text enclosed in single or double
quotes to a variable. To create multiline literals, assign the multiline text enclosed in triple
quotes. Eg.name=”Tanya”
A character literal– It is created by assigning a single character enclosed in double quotes. Eg.
a=’t’
Numeric literals include numeric values that can be either integer, floating point value, or a
complex number. Eg. a=50
Boolean literals– These can be 2 values- either True or False.
Literal Collections– These are of 4 types-
a) List collections-Eg. a=[1,2,3,’Amit’]
b) Tuple literals- Eg. a=(5,6,7,8)
c) Dictionary literals- Eg. dict={1: ’apple’, 2: ’mango, 3: ’banana`’}
d) Set literals- Eg. {“Tanya”, “Rohit”, “Mohan”}
6. Special literal- Python has 1 special literal None which is used to return a null variable.
And or Not Elif Else For While Break As Def Lamda Pass
Return True False Try With Assert Class Continue Del Except Finally From
Global Import In Is None Nonlocal Raise Yield

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Concatenating them by stacking the 2 dataframes vertically.
Concatenating them by stacking the 2 dataframes horizontally.
Combining them on a common column. This is referred to as joining.
New Dictionary functions Merge(|) and Update(|=)
New String Methods to Remove Prefixes and Suffixes
Type Hinting Generics in Standard Collections
New Parser based on PEG rather than LL1
New modules like zoneinfo and graphlib
Improved Modules like ast, asyncio, etc.
Optimizations such as optimized idiom for assignment, signal handling, optimized python
built ins, etc.
Deprecated functions and commands such as deprecated parser and symbol modules,
deprecated functions, etc.
Removal of erroneous methods, functions, etc.
Memory management in python is managed by Python private heap space. All Python
objects and data structures are located in a private heap. The programmer does not have
access to this private heap. The python interpreter takes care of this instead.
The allocation of heap space for Python objects is done by Python’s memory manager. The
core API gives access to some tools for the programmer to code.
Python also has an inbuilt garbage collector, which recycles all the unused memory and so
that it can be made available to the heap space.
15. How to combine dataframes in pandas?
The dataframes in python can be combined in the following ways-
1.
2.
3.
The concat() function is used to concatenate two dataframes. Its syntax is-
pd.concat([dataframe1, dataframe2]).
Dataframes are joined together on a common column called a key. When we combine all the
rows in dataframe it is union and the join used is outer join. While, when we combine the
common rows or intersection, the join used is the inner join. Its syntax is-
pd.concat([dataframe1, dataframe2], axis=’axis’, join=’type_of_join)
16. What are the new features added in Python 3.9.0.0 version?
The new features in Python 3.9.0.0 version are-
17. How is memory managed in Python?
Memory is managed in Python in the following ways:
1.
2.
3.

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os
sys
math
random
data time
JSON
18. What is namespace in Python?
A namespace is a naming system used to make sure that names are unique to avoid naming
conflicts.
19. What is PYTHONPATH?
It is an environment variable which is used when a module is imported. Whenever a module is
imported, PYTHONPATH is also looked up to check for the presence of the imported modules in
various directories. The interpreter uses it to determine which module to load.
20. What are python modules? Name some commonly used built-in modules in Python?
Python modules are files containing Python code. This code can either be functions classes or
variables. A Python module is a .py file containing executable code.
Some of the commonly used built-in modules are:
21. What are local variables and global variables in Python?
Global Variables:
Variables declared outside a function or in global space are called global variables. These
variables can be accessed by any function in the program.
22. Local Variables:
Any variable declared inside a function is known as a local variable. This variable is present in
the local space and not in the global space.
Example:
a=2
def add():
b=3
c=a+b
print(c)
add()
Output: 5
When you try to access the local variable outside the function add(), it will throw an error.

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Install python from this link: https://www.python.org/downloads/
After this, install it on your PC. Look for the location where PYTHON has been installed on your
PC using the following command on your command prompt: cmd python.
Then go to advanced system settings and add a new variable and name it as PYTHON_NAME
and paste the copied path.
Look for the path variable, select its value and select ‘edit’.
Add a semicolon towards the end of the value if it’s not present and then type
%PYTHON_HOME%
23. Is python case sensitive?
Yes. Python is a case sensitive language.
24. What is type conversion in Python?
Type conversion refers to the conversion of one data type into another.
int() – converts any data type into integer type
float() – converts any data type into float type
ord() – converts characters into integer
hex() – converts integers to hexadecimal
oct() – converts integer to octal
tuple() – This function is used to convert to a tuple.
set() – This function returns the type after converting to set.
list() – This function is used to convert any data type to a list type.
dict() – This function is used to convert a tuple of order (key, value) into a dictionary.
str() – Used to convert integer into a string.
complex(real,imag) – This function converts real numbers to complex(real,imag) number.
25. How to install Python on Windows and set path variable?
To install Python on Windows, follow the below steps:
26. Is indentation required in python?
Indentation is necessary for Python. It specifies a block of code. All code within loops, classes,
functions, etc is specified within an indented block. It is usually done using four space characters.
If your code is not indented necessarily, it will not execute accurately and will throw errors as well.
27. What is the difference between Python Arrays and lists?
Arrays and lists, in Python, have the same way of storing data. But, arrays can hold only a single
data type elements whereas lists can hold any data type elements.

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Example:
import array as arr
My_Array=arr.array('i',[1,2,3,4])
My_list=[1,'abc',1.20]
print(My_Array)
print(My_list)
Output:
array(‘i’, [1, 2, 3, 4]) [1, ‘abc’, 1.2]
28. What are functions in Python?
A function is a block of code which is executed only when it is called. To define a Python function, the
def keyword is used.
Example:
def Newfunc():
print("Hello World")
Newfunc(); #calling the function
Output: Hello World
29. What is __init__?
__init__ is a method or constructor in Python. This method is automatically called to allocate memory
when a new object/ instance of a class is created. All classes have the __init__ method.
Here is an example of how to use it.
class Employee:
def __init__(self, name, age,salary):
self.name = name
self.age = age
self.salary = 20000
E1 = Employee("XYZ", 23, 20000)
# E1 is the instance of class Employee.
#__init__ allocates memory for E1.
print(E1.name)
print(E1.age)
print(E1.salary)
Output:
XYZ
23
20000

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30. What is a lambda function?
An anonymous function is known as a lambda function. This function can have any number
of parameters but, can have just one statement.
Example:
a = lambda x,y : x+y
print(a(5, 6))
Output: 11
31. What is self in Python?
Self is an instance or an object of a class. In Python, this is explicitly included as the first
parameter. However, this is not the case in Java where it’s optional. It helps to
differentiate between the methods and attributes of a class with local variables.
The self variable in the init method refers to the newly created object while in other
methods, it refers to the object whose method was called.
32. How does break, continue and pass work?
Break
Allows loop termination when some condition is met and the
control is transferred to the next statement.
Continue
Allows skipping some part of a loop when some specific
condition is met and the control is transferred to the beginning
of the loop
Pass
Used when you need some block of code syntactically, but you
want to skip its execution. This is basically a null operation.
Nothing happens when this is executed.
35. What are python iterators?
Iterators are objects which can be traversed though or iterated upon.

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