*Editor's Note: Jonathan Trajkovic is a Data Analyst working for Synaltic in Paris, France. In this #HackerMonth blog post, Jonathan explains how he built a viz to simulate the results of a French presidential election. Check out more of Jonathan's work on his blog, Tips and Viz with Tableau!*

This month, Tableau Public launched Hacker Month to promote out of the ordinary vizzes. I chose to remake an old viz I did 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?!

The main trick is about using parameters. Indeed, I used parameters to allow users to simulate the final result as a function of the transfer of votes between candidates. Users can type a value from 0 to 100, and even give a little part to abstention. This trick is used to calculate the result for France and for each county. The parameters were inserted in calculations to provide a percentage corresponding to the candidate's result. Here is an example of the calculation:

```
(([% Voix/Exp HOLLANDE]+[% Voix/Exp BAYROU]*([BAYROU pour HOLLANDE]/100)+
[% Voix/Exp LE PEN]*([LE PEN pour HOLLANDE]/100)+[% Voix/Exp ARTHAUD]+
[% Voix/Exp JOLY]+[% Voix/Exp MÃ‰LENCHON]+[% Voix/Exp POUTOU])
/
([% Voix/Exp SARKOZY]+[% Voix/Exp BAYROU]*([BAYROU pour SARKOZY]/100)+
[% Voix/Exp LE PEN]*([LE PEN pour SARKOZY]/100)+[% Voix/Exp CHEMINADE]+
[% Voix/Exp DUPONT-AIGNAN]+[% Voix/Exp HOLLANDE]+[% Voix/Exp BAYROU]*([BAYROU pour HOLLANDE]/100)+
[% Voix/Exp LE PEN]*([LE PEN pour HOLLANDE]/100)+[% Voix/Exp ARTHAUD]+
[% Voix/Exp JOLY]+[% Voix/Exp MÃ‰LENCHON]+[% Voix/Exp POUTOU]))*100
```

The first part of the calculation is the percentage for the left side candidate and the second part is the total. This calculation gives me a percentage used in a bar chart. The same method was used to create the map (the difference is that I chose vote quantity instead of percentage).

Moreover, I tried to create a map which shows an overview of French counties as a function of the political side. This map was different compared to ones seen in the press. Indeed, this was not a map as a function of political party, and it tried to show a different view of French counties. For instance, it is not because a county chose UMP (right side) that the global trend is right side and vice-versa!

The last trick I used was to show bar charts in tooltips. This trick is really great because it allow users to know the distribution for each county. To do this a method is existing using special characters and formulas. Here is an example of calculation:

`Left("██████████████████████████████████████████████████",ROUND([% Gauche carte 2nd tour]/2))`

This calculation could be set in the tooltip to create a bar. In this case, the measure is relative (percentage) and divided by 2 because I used 50 special characters (and not 100). The result is a bar chart in the tooltip that we can customize (color, font, etc...).

The last trick I used 3 years ago was custom geocoding. Indeed, in 2012 counties for France was not available in Tableau Desktop. That is why I created a dataset allowing me to draw counties. If I had to remake it now, I think I will build the dataset in another way to make it easier to use.