#ParisAttacks - How Twitter tells the story

This is an analysis of Twitter's hashtags after the week-end. I used a website (www.takwalker.com) to get the data. The dataset is aggregated for each hour of each days from Friday 13rd November 2015 to today. I chose to try to tell the story with Twitter's data.

Hacker Month -- Tableau Public

French Presidential election in 2012

This month, Tableau Public launch the Hacker Month which promote out of the ordinary vizzes. I chose to remake an old viz I have done 3 years ago about the Presidential election. This viz was created during the "inter-rounds weeks" and the aim was to simulate the final result: who will be the next president ?!

How to create a radar chart in Tableau

Radar chart: I can see you...

After my last blog post about The Social Progress Index, I had a question about the creation of a radar chart. I will try to answer the question clearly during this blog post. On my own, I think radar chart is intersting if you want to compare members of a dimension in function of several metrics (you can also use Parallels coordinates). For example, when you want to buy a smartphone you can compare several devices with a radar chart (metrics: battery, camera, memory...). Let's try to explain how to create this in Tableau.

Trigonometry, my best friend ever!

To create a radar chart, I have to use trigonometry formulas... You remember the circle with Pi and number and stuff like that... ?

"Unit circle angles color" by Jim.belk - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

Well... It is important to use it to create axis and it depends on number of metrics you want to display. Indeed, if you want to display 5 axis (= 5 metrics) you have to use differents formulas than 6 axis chart. In my case I used a 12 axis chart so I had to use several formulas (as on the image above).
Thanks to Internet I was able to find the different formulas and create a calculation in Tableau for X axis and Y axis.

Calculation for [Xaxis]

case [Dimension]
    when "Member 1" then 0
    when "Member 2" then [Value] *(1/2)
    when "Member 3" then [Value] *(sqrt(3)/2)
    when "Member 4" then [Value]
    when "Member 4" then [Value] *(sqrt(3)/2)
    when "Member 5" then [Value] *(1/2)
    when "Member 6" then 0
    when "Member 7" then [Value] *(-1/2)
    when "Member 8" then [Value] *(-sqrt(3)/2)
    when "Member 9" then [Value] *(-1)
    when "Member 10" then [Value] *(-sqrt(3)/2)
    when "Member 11" then [Value] *(-1/2)
end

Calculation for [Yaxis]

case [Dimension]
    when "Member 1" then [Value]
    when "Member 2" then [Value]*(sqrt(3)/2)
    when "Member 3" then [Value]*(1/2)
    when "Member 4" then 0
    when "Member 5" then ([Value])*(-1/2)
    when "Member 6" then [Value]*(-sqrt(3)/2)
    when "Member 7" then [Value]*(-1)
    when "Member 8" then [Value]*(-sqrt(3)/2)
    when "Member 9" then [Value]*(-1/2)
    when "Member 10" then 0
    when "Member 11" then [Value]*(1/2)
    when "Member 12" then [Value]*(sqrt(3)/2)
end

It is very important to have the same [Value] scale for each [Dimension] members! Indeed, the 12 axis have to be the same. In my case the scale was from 0 to 100.

Build the radar to detect everything

After the creation of calculations, I had to build the chart. To do this, I just have to drag and drop the [Yaxis] on the lines shelf and the [Xaxis] on the columns shelf.

You can note that I use the aggregation Average (because Sum will returns a wrong result). Here I have only 1 point. To create the radar I have to use several dimensions (in my case, [Country] and [IndexType]). The [IndexType] allows me to draw 12 axis because this is a dimension with 12 members; [Country] allows me to draw 1 radar by country. If I want to draw the average radar chart, I can remove the [Country] field. To have several points I add [IndexType] on the Mark shelf as a Level of Detail.

After I can change the Mark to draw a polygon and add [Country] as a quick filter.

To have a beautiful radar, the last things to do are put [IndexType] as a Path to follow and Fix axis between -110 and 110 (or whatever you want to have enough space between borders and chart).

Some Formatting and "Voilà"!

To give some design to my chart, I chose to remove grid lines, Zero lines and borders, and to hide headers. Moreover, I chose to give some trnasparency and a border to my polygon in order to have a more beautiful chart.

Finally, I drew a background image to have reference axis in order to give some visual impact. Indeed, I think it is better if you know where the maximum is.

To add beautiful tooltips, it is important to put AVG([Value]) on the Mark shelf and to configure the tooltip like this:

And "Voilà"! The radar chart is done!

Thank you for the reading!

Which shape are you?

The Social Progress Index

Two weeks ago, I was browsing the Tableau community forum and I found an interesting question about reference line. The question was about to create a band reference line but just for few members in a dimension (Here is the question). This question drove me to an other question: Is it possible to create a "dynamic" reference line?

To answer it, I chose a dataset about Social metrics in the world: The Social Progress Index. With this dataset I tried to create a "dynamic" reference line.

As you can see in the visualisation below, when you click on a country on the map the reference line in the distribution graphic shows the average gap. The average gap is represented by a grey band calculated when the user click on a country. My idea was to show the gap when a country is highlighted and the average line in the other hand. To do this I used th LoD. It was just my second time with LoD... and it was very interesting!

The formula used in the LoD calculation allows me to calculate the general average: { EXCLUDE [Country]: avg([Value]) }. To build the reference band, I chose the average for each country as the end and my LoD calculation as the begin. The 9.0 version of Tableau allows me to show re-calculated reference lines when a mark is selected so I used it to redraw the reference band! Because in fact, the band is equal to 0 when no selection is provided. After this I chose to add some other graphics such as the radar graph to show the shape of each country and a map to allow the selection.

Feel free to leave a message or a note about this work!

Source:
The Social Progress Index - Data

Thank you for the reading!

Inside Airbnb dataset

Analysis of Airbnb data

Thanks to Jewel Loree from Tableau Public, I found a dataset about Airbnb. The timing was excellent because I had to choose an Airbnb accomodation for a training in Luxembourg a few weeks ago. When I discovered the website Inside Airbnb, I was suprised to find a lot of CSV files concerning several cities around the world. As a French, I chose to start my analysis with Paris but actually, I downloaded all the files to build the visualisation below.

IronViz Wiki Contest entry - The Eiffel Tower

History of the Eiffel Tower

IronViz time is here! This post is about my entry for the Wiki Contest. I have to admit that it was difficult to find a topic. First, I told me that it was too difficult to find a good and interesting topic with enough data and enough time to prepare these data... but in fact I found a topic yesterday evening during the Tableau User Group in Paris. During a conversation with co-leaders, they told me that we have to tell everybody : "French people do Tableau too !" That is why I choose to do a viz about The Eiffel Tower. I think it is a great construction and a great symbol for France!

You can find the viz just below. I tried to tell a story with the data of Wikipedia. I tried to present information about visitors, about the construction and the replicas. I put the sources just after the viz.

This post will be updated soon with more information about the method and the data.

Sources :
History of the Eiffel Tower
Technical details of the Eiffel Tower
Frequentation of the Eiffel Tower
Replicas of the Eiffel Tower
Welcome image

Thank you for the reading! And please vote for me!