# Machine Learning: Predicting house prices

February 16th, 2017 by
(http://blog.trifork.com/2017/02/16/machine-learning-predicting-house-prices/)

Recently i have followed an online course on machine learning to understand the current hype better. As with any subject though, only practice makes perfect, so i was looking to apply this new knowledge.

While looking to sell my house i found that would be a nice opportunity: Check if the prices a real estate agents estimates are in line with what the data suggests.

Linear regression algorithm should be a nice algorithm here, this algorithm will try to find the best linear prediction (y = a + bx1 + cx2 ; y = prediction, x1,x2 = variables). So for example this algorithm can estimate a price per square meter floor space or price per square meter of garden. For a more detailed explanation, check out the wikipedia page.

In the Netherlands funda is the main website for selling your house, so i have started by collecting some data, i used data on the 50 houses closest to my house. I’ve excluded apartments to try and limit data to properties similar to my house. For each house i collected the advertised price, usable floor space, lot size, number of (bed)rooms, type of house (row-house, corner-house, or detached) and year of construction (..-1930, 1931-1940, 1941-1950, 1950-1960, etc). These are the (easily available) variables i expected would influence house price the most. Type of house is a categorical variable, to use that in regression I modeled them as several binary (0/1) variables.

As preparation, i checked for relations between the variables using correlation. This showed me that much of the collected data does not seem to affect price: Only the floor space, lot size and number of rooms showed a significant correlation with house price.

For the regression analysis I only used the variables that had a significant correlation. Variables without correlation would not produce meaningful results anyway.

# GOTO Nights Amsterdam, Join & Learn!

March 8th, 2016 by
(http://blog.trifork.com/2016/03/08/goto-nights-amsterdam-join-learn/)

As an introduction to the GOTO Conference in June, we organize a monthly meetup to introduce you to the topics of the conference. These meetups are called GOTO Nights and are totally free to attend and food and drinks are included.

At the start of the GOTO season we gather together to decide which topics are interesting for developers to learn more about. For these topics we try to find the best speakers for the conference and for the GOTO Nights.

# Setting up PWM as a password recovery tool for OpenLDAP

July 28th, 2015 by

A running LDAP implementation without a password recovery service for users can be a real hassle for system administrators, in our case every time when a user forgets his/her password the only way to reset/change it was to go to the system administrator let him fix it.

As a solution for this problem we stumbled upon PWM as a password recovery service and in this blogpost will describe the steps you have to take to implement this yourself.

The reasons why we chose PWM as our service of choice are the following:

• Open-source and still being actively developed.
• It works with multiple LDAP implementations, including OpenLDAP.
• Pretty intuitive design for the end-user.
• A vast amount of configuration options, of which configuring our own password policy is one option.
• Able to recover password by sending and Email/SMS token or PIN.
• Event logs and statistics that are available to administrators.

The rest of this post will focus on walking through the installation and initial configuration of PWM with an OpenLDAP system. Most of the things we describe can also be found in the PWM administration guide or from other sources. However, some things (eg. configuration of certain modules in PWM) we didn’t immediately understand and we will describe some tips/solutions here.

# NewsBite April 2015

March 30th, 2015 by
(http://blog.trifork.com/2015/03/30/newsbite-march-2015/)

We have several news items that we would like to share with you. We have plenty of meetup activities and GOTO nights planned for the agenda that you don’t want to miss. The GOTO Amsterdam Schedule is now Live with core Tracks at this year’s event. 5th Keynote is all about Drones ! Additionally we have a new case study from FD to share and our partner elasticsearch changes name and  strategy Elastic: For – You Know, More Than Search Read on to learn more about all of this!

# THINK COMMUNITY…THINK GIVING BACK…THINK WELIKETOSHARE

At Trifork, we are not only passionate about what we do we are also passionate about giving back. Social responsibility starts with us … together we can make a difference.

Trifork is pleased to announce it collaboration with Weliketoshare. An online hotel price checker Weliketoshare has launched a new way to donate to charity. A way of donating that costs nothing extra for you. Book from over 700,000 hotels worldwide the cheapest hotel and automatically do something good for the world.Free of charge. Weliketoshare makes this possible, with every booking, we give a fixed portion of our income to charity projects. So choose a project and book your hotel, together we realize beautiful things!

Are you looking for a hotel for business or personal travel? Book your travel arrangements through our page and you too can make a difference!

# My Goto Amsterdam 2014

July 17th, 2014 by
(http://blog.trifork.com/2014/07/17/my-goto-amsterdam-2014/)

People who have worked with me know I’m a bit of a technical conservative. I’m very wary of quickly adopting the latest fads and trends because I’ve seen the collective hype and the following disillusionment too many times, including software being built with the then-latest-hype framework or platform and a year later being stuck with now-obsolete technology that only the original developers and a handful of other people still have any real experience with.

For the same reason I’ve avoided software tech conferences in the past years. A few visits to conferences several years ago on each occasion left me with feeling that I’d heard a lot about a lot, but that it wasn’t really going to improve my daily software development work.

Luckily, Goto Amsterdam 2014 was different.

Many, if not all, of the talks were relevant to my actual, day to day, software development job. I learned about looking at Agile in a different way. I heard people speak on real life problems being solved with actual, current, widely adopted technology. I even listened to talks that weren’t really that much about software development at all.

So let me walk you through my Goto Friday.