How is kNN different from k-means clustering?
kNN, or k-nearest neighbors is a classification algorithm, where the k is an integer describing the number of neighboring data points that influence the classification of a given observation. K-means is a clustering algorithm, where the k is an integer describing the number of clusters to be created from the given data. Both accomplish different tasks.

DATA SCIENCE INTERVIEW QUESTIONS WITH ANSWERS


1. What is a logistic function? What is the range of values of a logistic function?

f(z) = 1/(1+e -z )
The values of a logistic function will range from 0 to 1. The values of Z will vary from -infinity to +infinity.


2. What is the difference between R square and adjusted R square?

R square and adjusted R square values are used for model validation in case of linear regression. R square indicates the variation of all the independent variables on the dependent variable. i.e. it considers all the independent variable to explain the variation. In the case of Adjusted R squared, it considers only significant variables(P values less than 0.05) to indicate the percentage of variation in the model.

Thus Adjusted R2 is always lesser then R2.


3. What is stratify in Train_test_split?

Stratification means that the train_test_split method returns training and test subsets that have the same proportions of class labels as the input dataset. So if my input data has 60% 0's and 40% 1's as my class label, then my train and test dataset will also have the similar proportions.


4. What is Backpropagation in Artificial Neuron Network?

Backpropagation is the method of fine-tuning the weights of a neural network based on the error rate obtained in the previous epoch (i.e., iteration). Proper tuning of the weights allows you to reduce error rates and make the model reliable by increasing its generalization.

ENJOY LEARNING 👍👍

Core machine learning concepts explained through memes and simple charts created by Mihail Eric.

🔰 Python for Machine Learning & Data Science Masterclass

⏱ 44 Hours 📦 170 Lessons

Learn about Data Science and Machine Learning with Python! Including Numpy, Pandas, Matplotlib, Scikit-Learn and more!

Taught By: Jose Portilla

Download Full Course: https://t.iss.one/datasciencefree/69
Download All Courses: https://t.iss.one/datasciencefree/2

You are given a data set. The data set has missing values which spread along 1 standard deviation from the median. What percentage of data would remain unaffected? Why?

Answer: This question has enough hints for you to start thinking! Since, the data is spread across median, let’s assume it’s a normal distribution. We know, in a normal distribution, ~68% of the data lies in 1 standard deviation from mean (or mode, median), which leaves ~32% of the data unaffected. Therefore, ~32% of the data would remain unaffected by missing values.

Machine Learning Cheatsheet

#python #ml #cheatsheet #ai

Pattern Recognition and
Machine Learning [ Information Science and Statistics ]

Christopher M. Bishop
#python #machinelearning #statistics #information #ai #ml

📕 Introduction to Machine Learning
by Alex Smola and S.V.N. Vishwanathan

University Press, Cambridge

#numpy

NumPy

Smart use of ‘:’ to extract the right shape


Sometimes you encounter a 3-dim array that is of shape (N, T, D), while your function requires a shape of (N, D). At a time like this, reshape() will do more harm than good, so you are left with one simple solution:

Example:

for t in xrange(T):
x[:, t, :] = # ...

To become a Machine Learning Engineer:

• Python
• numpy, pandas, matplotlib, Scikit-Learn
• TensorFlow or PyTorch
• Jupyter, Colab
• Analysis > Code
• 99%: Foundational algorithms
• 1%: Other algorithms
• Solve problems ← This is key
• Teaching = 2 × Learning
• Have fun!

A LITTLE GUIDE TO HANDLING MISSING DATA
Having any Feature missing more than 5-10% of its values? you should consider it to be missing data or feature with high absence rate👀

How can you handle these missing values, ensuring you dont loose important part of your data🤷‍♀️
Not a problem😌. Here are important facts you must know😉

✍️Instances with missing values for all features should be eliminated
✍️Features with high absence rate should either be eliminated or filled with values
✍️Missing values can be replaced using Mean Imputation or Regression Imputation
✍️ Be careful with mean imputation for it may introduce bias as it evens out all instances
✍️Regression Imputation might overfit your model
✍️Mean and Regression Imputation can't be applied to Text features with missing values
✍️Text Features with missing values can be eliminated if not needed in data
✍️Important Text Features with Missing values can be replaced with a new class or category labelled as uncategorized

Top 8 Github Repos to Learn Data Science and Python

1. All algorithms implemented in Python
By: The Algorithms
Stars ⭐️: 135K
Fork: 35.3K
Repo: https://github.com/TheAlgorithms/Python

2. DataScienceResources
By: jJonathan Bower
Stars ⭐️: 3K
Fork: 1.3K
Repo: https://github.com/jonathan-bower/DataScienceResources

3. Playground and Cheatsheet for Learning Python
By: Oleksii Trekhleb ( Also the Image)
Stars ⭐️: 12.5K
Fork: 2K
Repo: https://github.com/trekhleb/learn-python


4. Learn Python 3
By: Jerry Pussinen
Stars ⭐️: 4,8K
Fork: 1,4K
Repo: https://github.com/jerry-git/learn-python3


5. Awesome Data Science
By: Fatih Aktürk, Hüseyin Mert & Osman Ungur, Recep Erol.
Stars ⭐️: 18.4K
Fork: 5K
Repo: https://github.com/academic/awesome-datascience

6. data-scientist-roadmap
By: MrMimic
Stars ⭐️: 5K
Fork: 1.5K
Repo: https://github.com/MrMimic/data-scientist-roadmap


7. Data Science Best Resources
By: Tirthajyoti Sarkar
Stars ⭐️: 1.8K
Fork: 717
Repo: https://github.com/tirthajyoti/Data-science-best-resources/blob/master/README.md


8. Ds-cheatsheets
By: Favio André Vázquez
Stars ⭐️: 10.4K
Fork: 3.1K
Repo: https://github.com/FavioVazquez/ds-cheatsheets

💥Deep Learning with Pytorch by Prof.Yann LeCun (CNN Founder)

This course concerns the latest techniques in deep learning and representation learning, focusing on supervised and unsupervised deep learning, embedding methods, metric learning, convolutional and recurrent nets, with applications to computer vision, natural language understanding, and speech recognition.

GitHub Link: https://atcold.github.io/pytorch-Deep-Learning/

YouTube Playlist: https://www.youtube.com/playlist?list=PLLHTzKZzVU9eaEyErdV26ikyolxOsz6mq

Probability Cheat Sheet
👇👇
https://web.cs.elte.hu/~mesti/valszam/kepletek

New Data Scientists - When you learn, it's easy to get distracted by Machine Learning & Deep Learning terms like "XGBoost", "Neural Networks", "RNN", "LSTM" or Advanced Technologies like "Spark", "Julia", "Scala", "Go", etc.

Don't get bogged down trying to learn every new term & technology you come across.

Instead, focus on foundations.
- data wrangling
- visualizing
- exploring
- modeling
- understanding the results.

The best tools are often basic, Build yourself up. You'll advance much faster. Keep learning!

Data Analysis Interview Questions and Answers
👇👇

1.How to create filters in Power BI?

Filters are an integral part of Power BI reports. They are used to slice and dice the data as per the dimensions we want. Filters are created in a couple of ways.

Using Slicers: A slicer is a visual under Visualization Pane. This can be added to the design view to filter our reports. When a slicer is added to the design view, it requires a field to be added to it. For example- Slicer can be added for Country fields. Then the data can be filtered based on countries.
Using Filter Pane: The Power BI team has added a filter pane to the reports, which is a single space where we can add different fields as filters. And these fields can be added depending on whether you want to filter only one visual(Visual level filter), or all the visuals in the report page(Page level filters), or applicable to all the pages of the report(report level filters)


2.How to sort data in Power BI?

Sorting is available in multiple formats. In the data view, a common sorting option of alphabetical order is there. Apart from that, we have the option of Sort by column, where one can sort a column based on another column. The sorting option is available in visuals as well. Sort by ascending and descending option by the fields and measure present in the visual is also available.


3.How to convert pdf to excel?

Open the PDF document you want to convert in XLSX format in Acrobat DC.
Go to the right pane and click on the “Export PDF” option.
Choose spreadsheet as the Export format.
Select “Microsoft Excel Workbook.”
Now click “Export.”
Download the converted file or share it.


4. How to enable macros in excel?

Click the file tab and then click “Options.”
A dialog box will appear. In the “Excel Options” dialog box, click on the “Trust Center” and then “Trust Center Settings.”
Go to the “Macro Settings” and select “enable all macros.”
Click OK to apply the macro settings.

————————————————————-

ENJOY LEARNING 👍👍