How Do You Identify And Deal With Missing Values
Identifying missing values
We can identify missing values in the DataFrame by using the `isnull` function and then applying `sum`. `Isnull` will return boolean values, and the sum will give you the number of missing values in each column.
In the example, we have created a dictionary of lists and converted it into a pandas DataFrame. After that, we used isnull.sum to get the number of missing values in each column.
import pandas as pdimport numpy as np# dictionary of listsdict = # creating a DataFramedf = pd.DataFramedf.isnull.sum# id 1# Age 2# Score 1
Dealing with missing values
There are various ways of dealing with missing values.
Note: make sure you are working with a larger dataset while using the `dropna` function.
# drop missing valuesdf.dropna#fillnadf.fillna#replace null values with -999df.replace# Interpolatedf.interpolate
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- People who eager to ace the coding interview at companies like Google, Amazon, Microsoft, Facebook, etc.
- People who want to develop their problem solving skills.
- Students getting ready for their coding interviews.
- People who want to get better at competitive programming.
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What Are The Benefits Of Using Python
Your hiring manager might ask you this question to assess your familiarity with the program and to make sure you understand when using Python is most beneficial. In your answer, try to communicate your in-depth knowledge of the program and comprehensive understanding of its applications.
Example answer:”There are many benefits to using Python. For one, it’s relatively easy to read and write. The syntax is intuitive, which can improve productivity and reduce errors. I also appreciate that it’s an open-source program because there are so many ways you can adapt it to fit the needs of a specific project or ask a specific question to the community. I’ve been able to experiment with the program in my free time because of its accessibility. I just think it’s a very versatile language with lots of diverse applications and uses.”
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Write A Program To Generate A List Of Fibonacci Numbers
Recall that the Fibonacci sequence is generated by starting with two integers: 1 and 2. The next number in the sequence is found by adding the previous two numbers together. This question can be answered in a number of different ways. One possible solution uses Python generators and is shown below.
This would be a good opportunity to impress the interviewer with your knowledge of Python generator functions and how they can be used to return lazy iterators in your code. You can speak to a generatorâs advantages such as time and memory efficiency as well as making Python code concise and clear.
Fair For All Candidates
Weve built our platform and tests on the standards of the Equal Employment Opportunity Commission to remove unconscious bias from the hiring process. This means youll see your best candidates ranked the highest regardless of gender, race, ethnicity, or age. We also periodically use differential item functioning studies performed on data collected from candidates. This helps us to continually remove any potential adverse impact from the hiring process.
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What Is An Iterator In Python
Ask candidates this question to learn whether they have in-depth knowledge of this critical feature in Python.
Amazon Python Interview Questions
Amazon Python interview questions can vary greatly but could include:
18. Find the missing number in the array
You have been provided with the list of positive integers from 1 to n. All the numbers from 1 to n are present except x, and you must find x.
def checkTriplet: n = len for i in range: array = array**2 array.sort for i in range: s = set for j in range: if in s: return True s.add return Falsearr = checkTriplet# True
20. How many ways can you make change with coins and a total amount?
We need to create a function that takes a list of coin denominations and total amounts and returns the number of ways we can make the change.
In the example, we have provided coin denominations and the total amount of 5. In return, we got five ways we can make the change.
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Differentiate Between Deep And Shallow Copies
- Shallow copy does the task of creating new objects storing references of original elements. This does not undergo recursion to create copies of nested objects. It just copies the reference details of nested objects.
- Deep copy creates an independent and new copy of an object and even copies all the nested objects of the original element recursively.
Explain What Functions In Python Are
Are your candidates savvy when it comes to the technical aspects of Python? If they are, they should know what functions are.
The best responses will identify that functions might be described as code blocks that need to be called if you want to execute them. Candidates might also explain that if you wanted to define functions in Python, youd use the keyword def.
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.
What Is Zip Function In Python
Python zip function returns a zip object, which maps a similar index of multiple containers. It takes an iterable, convert into iterator and aggregates the elements based on iterables passed. It returns an iterator of tuples.
iterator1, iterator2, iterator3: These are iterator objects that are joined together.
It returns an iterator from two or more iterators.
Note: If the given lists are of different lengths, zip stops generating tuples when the first list ends. It means two lists are having 3, and 5 lengths will create a 3-tuple.
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What Is The Procedure To Install Python On Windows And Set Path Variables
We need to implement the following steps to install Python on Windows, and they are:
- First, you need to install Python from https://www.python.org/downloads/
- After installing Python on your PC, find the place where it is located in your PC using the cmd python command.
- Then visit advanced system settings on your PC and add a new variable. Name the new variable as PYTHON_NAME then copy the path and paste it.
- Search for the path variable and select one of the values for it and click on edit.
- Finally, we need to add a semicolon at the end of the value, and if the semicolon is not present then type %PYTHON_NAME%.
Which Sorts Of Roles Are Python Interview Questions Ideal For
In addition to software development, programming, and engineering positions, Python interview questions are ideal for data analysts. But thats not all. Some more positions for which you might use Python interview questions include:
- Machine learning engineer roles
- Python developer jobs
- Jobs in the field of artificial intelligence
To get the most out of your interviews, you should always align the interview questions to the role you are hiring for, as well as to your organizations needs.
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Python Programming Library Interview Questions
Q.23. Can I dynamically load a module in Python?
Dynamic loading is where we do not load a module till we need it. This is slow, but lets us utilize the memory more efficiently. In Python, you can use the importlib module for this:
import importlibmodule = importlib.import_module
Q.24. What is speech_recognition? Does this ship with Python by default?
Speech_recognition is a library for performing the task of recognizing speech with Python. This forms an integral part of AI. No, this does not ship with Python by default. We must download it from the PyPI and install it manually using pip.
Score High in Interview Dont forget to practice Speech Emotion Recognition Python Project with Source Code
Q.25. How would you generate a random number in Python?
To generate a random number, we import the function random from the module random.
> > > from random import random> > > random
Lets call for help on this.
> > > help
Help on built-in function random:
random method of random.Random instance
random -> x in the interval [0, 1).
This means that it will return a random number equal to or greater than 0, and less than 1.
We can also use the function randint. It takes two arguments to indicate a range from which to return a random integer.
> > > from random import randint> > > randint
Q.26. How will you locally save an image using its URL address?
For this, we use the urllib module.
> > > import urllib.request> > > urllib.request.urlretrieve
Advanced Python Data Science Interview Questions And Answers
Go through the following python interview questions for data science that are slightly advanced. These python data science interview questions might be difficult for you to answer but it is important that you prepare for these python interview questions as well before going for your interview.
1) How will you use Pandas library to import a CSV file from a URL?
import pandas as pd
2) How will you transpose a NumPy array?
3) What are universal functions for n-dimensional arrays?
Universal functions are the functions that perform mathematical operations on each element of an n-dimensional array. Example: np.sqrt and np.exp evaluate square root and exponential of each element of an array respectively.
4) List a few statistical methods available for a NumPy array.
np.means, np.cumsum, np.sum,
5) What are boolean arrays? Write a code to create a boolean array using the NumPy library.
A boolean array is an array whose elements are of the boolean data type. A vital point to remember is that for boolean arrays, Python keywords and and or do not work.
Barr = np.array
6) What is Fancy Indexing?
IN NumPy, one can use an integer list to describe the indexing of NumPy arrays. For example, Array] for an array of dimensions 4×4 will print the rows in the order specified by the list.
7) What is NaT in Pythons Pandas library?
NaT stands for Not a Time. It is the NA value for timestamp data
8) What is Broadcasting for NumPy arrays?
This can be represented by the following image:
What Advantages Do Numpy Arrays Offer Over Python Lists
- Python lists are efficient general-purpose containers that support efficient operations like insertion,appending,deletion and concatenation.
- The limitations of lists are that they dont support vectorized operations like element wise addition and multiplication, and the fact that they can contain objects of differing types mean that Python must store type information for every element, and must execute type dispatching code when operating on each element.
- NumPy is more efficient and more convenient as you get a lot of vector and matrix operations for free, which helps to avoid unnecessary work and complexity of the code.Numpy is also efficiently implemented when compared to nested
- NumPy array is faster and contains a lot of built-in functions which will help in FFTs, convolutions, fast searching, linear algebra,basic statistics, histograms,etc.
What Are The Different Types Of Operators In Python
Python uses a rich set of operators to perform a variety of operations. Some individual operators like membership and identity operators are not so familiar but allow to perform operations.
- Arithmetic OperatorsRelational Operators
- Identity Operators
- Bitwise Operators
Arithmetic operators perform basic arithmetic operations. For example “+” is used to add and “?” is used for subtraction.
Relational Operators are used to comparing the values. These operators test the conditions and then returns a boolean value either True or False.
# Examples of Relational Operators
Assignment operators are used to assigning values to the variables. See the examples below.
Logical operators are used to performing logical operations like And, Or, and Not. See the example below.
Membership operators are used to checking whether an element is a member of the sequence or not. Python uses two membership operators in and not in operators to check element presence. See an example.
Identity Operators both are used to check two values or variable which are located on the same part of the memory. Two variables that are equal does not imply that they are identical. See the following examples.
Bitwise Operators are used to performing operations over the bits. The binary operators work on bits. See the example below.
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What Are The Advantages Of Numpy Over Regular Python Lists
Numpy arrays consume less memory.
For example, if you create a list and a Numpy array of a thousand elements. The list will consume 48K bytes, and the Numpy array will consume 8k bytes of memory.
Numpy arrays take less time to perform the operations on arrays than lists.
For example, if we are multiplying two lists and two Numpy arrays of 1 million elements together. It took 0.15 seconds for the list and 0.0059 seconds for the array to operate.
Numpy arrays are convenient to use as they offer simple array multiple, addition, and a lot more built-in functionality. Whereas Python lists are incapable of running basic operations.
Attend Seminars And Webinars
There are numerous contents available on the internet which you can go through. From detailed webinars to small workshops, make sure to attend those to brush up on your basic skills. You can also become a part of a concept which you have never heard of in programming. This way you can reinvent your ways of learning.
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What Are The Important Features Of Python
- Python is a scripting language. Python, unlike other programming languages like C and its derivatives, does not require compilation prior to execution.
- Python is dynamically typed, which means you don’t have to specify the kinds of variables when declaring them or anything.
- Python is well suited to object-oriented programming since it supports class definition, composition, and inheritance.
What Are The Python Coding Interview Questions
Python coding interview questions are asked to test your Python coding expertise and analytical skills. For example, you can expect the questions related to keywords, architecture, ORM, frameworks, how to solve a particular scenario, how to write a code or what is the output of the program, etc. Learn 30+ Python coding interview questions and answers here in this blog.
Python Technical Interview Questions
Q.15. When you exit Python, is all memory deallocated?
Exiting Python deallocates everything except:
- modules with circular references
- Objects referenced from global namespaces
- Parts of memory reserved by the C library
Q.16. What is the Dogpile effect?
In case the cache expires, what happens when a client hits a website with multiple requests is what we call the dogpile effect. To avoid this, we can use a semaphore lock. When the value expires, the first process acquires the lock and then starts to generate the new value.
Q.17. Explain garbage collection with Python.
The following points are worth nothing for the garbage collector with CPython-
- Python maintains a count of how many references there are to each object in memory
- When a reference count drops to zero, it means the object is dead and Python can free the memory it allocated to that object
- The garbage collector looks for reference cycles and cleans them up
- Python uses heuristics to speed up garbage collection
- Recently created objects might as well be dead
- The garbage collector assigns generations to each object as it is created
- It deals with the younger generations first.
Q.18. How will you use Python to read a random line from a file?
We can borrow the choice method from the random module for this.
> > > import random> > > lines=open.read.splitlines> > > random.choice
Lets restart the IDLE and do this again.
> > > random.choice