Cross validation is an essential tool in statistical learning to estimate the accuracy of your algorithm. Despite its great power it also exposes some fundamental risk when done wrong which may terribly bias your accuracy estimate. In this blog post I'll demonstrate - using the Python scikit-learn framework - how to avoid the biggest and […]
Author: mottalrd
Data manipulation primitives in R and Python
Both R and Python are incredibly good tools to manipulate your data and their integration is becoming increasingly important. The latest tool for data manipulation in R is Dplyr whilst Python relies on Pandas. In this blog post I'll show you the fundamental primitives to manipulate your dataframes using both libraries highlighting their major advantages […]
Thoughts on the Railsconf 2015 Keynote
This year Rails 5 will be released and the Railsconf keynote held by DHH - the author of Rails - presents the rationale behind its latest developments. In the following I'll show you why I think we are riding the good Rails and how to apply the right amount of criticism around the Rails' author […]
Upload video files with progress bar using Rails, Paperclip and Javascript
Rails does not help much when dealing with AJAX uploads by means of external JS libraries. I recently came across a case where a user on www.codementor.io was struggling to use JQuery-upload-file to upload a video to a Rails backend. The main reason to use the library was the progress bar feature, something that is […]
Understanding the Resque internals - Resque::DirtyExit unveiled
If your Resque jobs fail because of a mysterious Resque::DirtyExit a quick tour of the Resque internals will help you fix the issue and be back up and running in a matter of minutes.
Bringing Ruby fetch to the Javascript world
If you are a Rubyist you are probably comfortable using the fetch method on a day-to-day basis but when you are developing in Javascript this sweetness is not immediately available. This is why I wrote underscorejs-fetch.
Refactoring a complex Javascript calendar
Frontend components are hard to implement and more often than not the code reflects this complexity. In this blog post I will show you how I refactored the code of a complex frontend calendar sharing some of the findings that led to a cleaner implementation.
A journey through a Web App optimization session
Fast web apps are beautiful to use and are one of the key requirements for a successful user experience. Not only, if you are running an e-commerce business being faster also have a great impact on revenue. Here I will show you how to analyze and speedup the performance of your web app for two […]
Compute property recommendations: A collaborative filtering approach
In this blog post I'll show how to build a simple recommendation engine for apartments. What are the possible design choices, how to implement them in practice, and how to validate the performance of your system.