# Tag: Data Science

## Recommender System in Python

The Amazon and Netflix are making almost 50% of their revenues by recommending appropriate products (books, movies) to their users. But how do they know what to recommend to their users? Well, they use the power of the collaboration between all other items and users. Collaborative Filtering(CF) is maybe the most popular method in Recommender ...

## Java MapReduce for top N Twitter Hashtags

Back in 2015 i had to implement MapReduce job to extract top 15 hashtags from twitter’s raw data in Hadoop. This was a part of Business Intelligence lecture exercise at Vienna University of Technology. Regex used (not the best one by my opinion), for hashtag extraction, has following format: String regex = “text\”:\\\”(.*)\\\”,\”source”; The ‘source’ field comes ...

## Linear Regression with multiple Variables in Matlab

In the previous post I showed you how to implement Linear Regression with one Variable in Matlab. In this one I’m going to discuss implementation with multiple variables. Before implementing multivariate Linear Regression, feature normalization would be the smart step since the gradient descent would converge (would find minimum cost function) much more quickly. Every sample value is ...

## Linear Regression with one Variable in Matlab

In this post i will show you how to implement one of the basic Machine Learning concepts in Matlab, the Linear Regression with one Variable. Matlab and Octave are very useful high-level languages for prototyping Machine Learning algorithms. [Linear Regression Example from mathworks.com] The idea is to find the line that perfectly fits all ...

## Distribute Missing Values randomly across rolumns in Python Pandas

Continuing to the previous post this script distributes missing values across all features in Pandas DataFrame. Just set min and max missing value distribution and you’re ready to execute … Enjoy…

## Distribute Missing Values in Pandas DataFrame Column with Python

If you want to test how Maschine Learning algorithms perform with missing values you may need a script to distribute a fixed percentage of missing values in a feature. This script randomly distributes missing values in a single data set’s column. Enjoy…

## Feature Scaling in Python and Pandas DataFrame

Hire is a small script that i wrote long time ago to scale some of the features in order to get better performance and better prediction results in some ML algorithms. I used Python with Pandas to read in the CSV file and process feature values. Formulas for feature scaling used in the script can be found ...