Why Should We Use The Django Framework
The main goal to designing Django is to make it simple to its users, to do this Django uses:
- The principles concerning rapid development, which implies developers can complete more than one iteration at a time without beginning the full schedule from scratch
- DRY philosophy Do not Replicate Yourself that means developers can reuse surviving code and also focus on the individual one.
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Does Multiple Inheritances Are Supported In Python
Multiple inheritances are supported in python. It is a process that provides flexibility to inherit multiple base classes in a child class.
An example of multiple inheritances in Python is as follows:
class Calculus: def Sum: return a+b class Calculus1: def Mul: return a*b class Derived: def Div: return a/b d = Derived print) print) print)
How Are Arguments Passed By Value Or By Reference In Python
- Pass by value: Copy of the actual object is passed. Changing the value of the copy of the object will not change the value of the original object.
- Pass by reference: Reference to the actual object is passed. Changing the value of the new object will change the value of the original object.
In Python, arguments are passed by reference, i.e., reference to the actual object is passed.
defappendNumber: arr.appendarr = print #Output: => appendNumberprint #Output: =>
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Q How To Retrieve Data From A Table In Mysql Database Through Python Code Explain
#import MySQLdb module as : importMySQLdb#establish a connection to the database.db=MySQLdb.connect#initialize the cursor variable upon the established connection: c1=db.cursor#retrieve the information by defining a required query string.s="Select * from dept"#fetch the data using fetch methods and print it. data=c1.fetch#close the database connection. db.close
What Is The Significance Of Local And Global Variables In Python
Answer: Local and global variables are kinds of variables with different scopes.
Scope: The part of the code that can access a particular variable, represents the scope of that variable.
A variable that is declared/defined within a function or class, is local to that function or class. The existence of the variable will be till the control remains within that function or class. These variables cannot be accessed from outside its scope.
sum_result = number_first + number_second
Summation #calling the function
Thus, from the above example, we understand that number_first, number_second, and sum are local variables to the function Summation.
It cannot be accessed from outside the function Summation.
Error shown for trying to access local variables from outside the scope is as below:
When a variable is declared/defined outside of a function or class, it can be accessed from outside that function or class. Such variables fall under global variables. In other words, when a variable is not enclosed within a class or function, its scope runs throughout the program and will only cease to exist when the execution is terminated.
sum_result = number_first+number_second #accessing the global variable
Summation #calling the function
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What Are The Important Errors In Python
Important errors represent logical places for a programmer to look for errors in the code. The candidate must be able to identify the most important errors and how to fix them. What to look for in an answer:
- Can name all three important errors
- A brief explanation of each
- Can describe what error handling accomplishes
“There are three important errors I look for. They are the ArithmeticError, ImportError, and the IndexError. The Arithmetic Error is when arithmetic operations need revisions. The ImportError occurs when a typo in a module missing from the standard path, or in the module name. The IndexError happens when you reference an out-of-range sequence. These errors come up when the interpreter comes across them. Handling errors add to the strength of the code, guarding against failures causing the program to close.”
How Multithreading Is Achieved In Python
- Although Python includes a multi-threading module, it is usually not a good idea to utilize it if you want to multi-thread to speed up your code.
- As this happens so quickly, it may appear to the human eye that your threads are running in parallel, but they are actually sharing the same CPU core.
- The Global Interpreter Lock is a Python concept . Only one of your ‘threads’ can execute at a moment, thanks to the GIL. A thread obtains the GIL, performs some work, and then passes the GIL to the following thread.
Q What Do You Mean By Overriding Methods
Ans. Suppose class B inherits from class A. Both have the method sayhello- to each, their own version. B overrides the sayhello of class A. So, when we create an object of class B, it calls the version that class B has.
Hello, I’m A
How Do You Handle Exceptions In Python
Exception handling follows the try-except structure:
try: # try to run this block of codeexcept: # do this if try block failsfinally: # always run this block
try: test = 1 + "one"except: print test = 10finally: printprint
Exception encountered! Default value will be usedThis is always run10
In the above, the test = 1 + “one” fails because summing a string and a number is not possible. The except block catches this error and runs some code.
With exception handling, your program does not crash. Instead, it resolves the error cases and continues to run.
Q Explain Relational Operators In Python
Relational operators compare values.
- Less than If the value on the left is lesser, it returns True.
Greater than If the value on the left is greater, it returns True. 1.1 + 2.2 > 3.3
This is because of the flawed floating-point arithmetic in Python, due to hardware dependencies.
Less than or equal to If the value on the left is lesser than or equal to, it returns True. 3.0 < = 3
Greater than or equal to If the value on the left is greater than or equal to, it returns True. True > = False
Equal to If the two values are equal, it returns True. ==
Not equal to If the two values are unequal, it returns True. True!=0.1
How Do You Access Parent Members In The Child Class
Following are the ways using which you can access parent class members within a child class:
- You can use the name of the parent class to access the attributes as shown in the example below:
classParent:# Constructordef__init__: self.name = name classChild:# Constructordef__init__: Parent.name = name self.age = agedefdisplay:print# Driver Codeobj = Childobj.display
- The parent class members can be accessed in child class using the super keyword.
classParent:# Constructordef__init__: self.name = name classChild:# Constructordef__init__:''' In Python 3.x, we can also use super.__init__ ''' super.__init__ self.age = agedefdisplay:# Note that Parent.name cant be used # here since super is used in the constructorprint# Driver Codeobj = Childobj.display
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Save Memory With Generators
List comprehensions are convenient tools but can sometimes lead to unnecessary memory usage.
Imagine youve been asked to find the sum of the first 1000 perfect squares, starting with 1. You know about list comprehensions, so you quickly code up a working solution:
> > > sum333833500
Your solution makes a list of every perfect square between 1 and 1,000,000 and sums the values. Your code returns the right answer, but then your interviewer starts increasing the number of perfect squares you need to sum.
At first, your function keeps popping out the right answer, but soon it starts slowing down until eventually the process seems to hang for an eternity. This is the last thing you want happening in a coding interview.
Whats going on here?
Its making a list of every perfect square youve requested and summing them all. A list with 1000 perfect squares may not be large in computer-terms, but 100 million or 1 billion is quite a bit of information and can easily overwhelm your computers available memory resources. Thats whats happening here.
Thankfully, theres a quick way to solve the memory problem. You just replace the brackets with parentheses:
> > > sum))333833500
Swapping out the brackets changes your list comprehension into a generator expression. Generator expressions are perfect for when you know you want to retrieve data from a sequence, but you dont need to access all of it at the same time.
Q How Do I Test A Python Program Or Component
Python comes with two testing frameworks:The documentation test module finds examples in the documentation strings for a module and runs them, comparing the output with the expected output given in the documentation string.
The unittest moduleis a fancier testing framework modeled on Java and Smalltalk testing frameworks.
For testing, it helps to write the program so that it may be easily tested by using good modular design. Your program should have almost all functionality encapsulated in either functions or class methods. And this sometimes has the surprising and delightful effect of making the program run faster because local variable accesses are faster than global accesses.
Furthermore the program should avoid depending on mutating global variables, since this makes testing much more difficult to do.The “global main logic” of your program may be as simple as:
at the bottom of the main module of your program.Once your program is organized as a tractable collection of functions and class behaviors, you should write test functions that exercise the behaviors.
A test suite can be associated with each module which automates a sequence of tests.
You can make coding much more pleasant by writing your test functions in parallel with the “production code”, since this makes it easy to find bugs and even design flaws earlier.
“Support modules” that are not intended to be the main module of a program may include a self-test of the module.
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Q30 What Is Self In Python
Ans: 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 its 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.
How To Crack A Coding Interview
It is not that easy as we usually think. Mugging up some programs and executing the same will not work. The ideal way to crack the coding interview, you should be proficient in writing code without the support of any IDE. Don’t panic or argue, test your code before you submit, wait for their feedback. Practicing mock interviews will help. Coderbyte platform will help you in enhancing your skills.
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What Is A Map Function In Python
The map function in Python has two parameters, function and iterable. The map function takes a function as an argument and then applies that function to all the elements of an iterable, passed to it as another argument. It returns an object list of results.
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How Can You Insert Elements In Array
Python array insert operation enables you to insert one or more items into an array at the beginning, end, or any given index of the array. This method expects two arguments index and value.
The syntax is
Let us add a new value right after the second item of the array. Currently, our balance array has three items: 300, 200, and 100. Consider the second array item with a value of 200 and index 1.
In order to insert the new value right after index 1, you need to reference index 2 in your insert method, as shown in the below Python array example:
import arraybalance = array.arraybalance.insertprint
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How To Install Python On Windows And Set A Path Variable
For installing Python on Windows, follow the steps shown below:
- After that, install it on your PC by looking for the location where PYTHON has been installed on your PC by executing the following command on command prompt
- Visit advanced system settings and after that add a new variable and name it as PYTHON_NAME and paste the path that has been copied.
- Search for the path variable -> select its value and then select edit.
- Add a semicolon at the end of the value if its not present and then type %PYTHON_HOME%
Iterate With Enumerate Instead Of Range
This scenario might come up more than any other in coding interviews: you have a list of elements, and you need to iterate over the list with access to both the indices and the values.
Theres a classic coding interview question named FizzBuzz that can be solved by iterating over both indices and values. In FizzBuzz, you are given a list of integers. Your task is to do the following:
Often, developers will solve this problem with range:
> > > numbers=> > > foriinrange):... ifnumbers%3==0andnumbers%5==0:... numbers='fizzbuzz'... elifnumbers%3==0:... numbers='fizz'... elifnumbers%5==0:... numbers='buzz'...> > > numbers
Range allows you to access the elements of numbers by index and is a useful tool for some situations. But in this case, where you want to get each elements index and value at the same time, a more elegant solution uses enumerate:
> > > numbers=> > > fori,numinenumerate:... ifnum%3==0andnum%5==0:... numbers='fizzbuzz'... elifnum%3==0:... numbers='fizz'... elifnum%5==0:... numbers='buzz'...> > > numbers
For each element, enumerate returns a counter and the element value. The counter defaults to 0, which conveniently is also the elements index. Dont want to start your count at 0? Just use the optional start parameter to set an offset:
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Explain The Procedure To Minimize Or Lower The Outages Of The Memcached Server In Your Python Development
The following are the steps used to minimize the outages of the Memcached server in your Python development, and they are.
- When a single instance fails, this will impact on larger load of the database server. The client makes the request when the data is reloaded. In order to avoid this, the code that you have written must be used to lower cache stampedes then it will be used to leave a minimal impact.
- The other way is to bring out the instance of the Memcached on a new machine by using the IP address of the lost machine.
- Another important option is to lower the server outages is code. This code provides you with the liberty to modify the Memcached server list with minimal work
- another way is by setting a timeout value that will be one of the options for memcac
Class Student:def __init__:self.name = nameS1=Studentprint
- hed clients to implement the Memcached server outage. When the performance of the server goes down, the client keeps on sending a request until the timeout limit is reached.
What Are The Types Of Literals In Python
For primitive data types, a literal in Python source code indicates a fixed value. Following are the 5 types of literal in Python:
- String Literal: A string literal is formed by assigning some text to a variable that is contained in single or double-quotes. Assign the multiline text encased in triple quotes to produce multiline literals.
- Numeric Literal: They may contain numeric values that are floating-point values, integers, or complex numbers.
- Character Literal: It is made by putting a single character in double-quotes.
- Boolean Literal: True or False
- Literal Collections: There are four types of literals such as list collections, tuple literals, set literals, dictionary literals, and set literals.
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What Are The Applications Of Python
Python is used in various software domains some application areas are given below.
- Web and Internet Development
- Image processing and graphic design applications
- Enterprise and business applications development
- Operating systems
- GUI based desktop applications
Python provides various web frameworks to develop web applications. The popular python web frameworks are Django, Pyramid, Flask.
Python’s standard library supports for E-mail processing, FTP, IMAP, and other Internet protocols.
Python’s SciPy and NumPy helps in scientific and computational application development.
Python’s Tkinter library supports to create a desktop based GUI applications.
Python Basic Interview Questions
1. Briefly explain some characteristics of Python.
Python is a general purpose, high-level, interpreted language. It was specifically developed with the purpose of making the content readable. Python has often been compared to the English language, and it also has fewer syntactic constructions compared to other languages.
2. What are some distinct features of Python?
Some distinct features of Python are:
3. What is Pythonpath?
A Pythonpath tells the Python interpreter to locate the module files that can be imported into the program. It includes the Python source library directory and source code directory. You can preset Pythonpath as a Python installer.
4. Why do we use the Pythonstartup environment variable?
The variable consists of the path in which the initialization file carrying the Python source code can be executed. This is needed to start the interpreter.
5. What is the Pythoncaseok environment variable?
The Pythoncaseok environment variable is applied in Windows with the purpose of directing Python to find the first case insensitive match in an import statement.
6. What are the supported standard data types in Python?
Example: tup =
Example: L =
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