Tuesday, March 19, 2019

Who Will Win the Global City Race?

Animated bar chart races have suddenly become a very popular method for visualizing data over time. Their recent popularity owes much to John Murdoch's 18 Years of Interbrand’s Top Global Brands.

This animated bar chart race shows the brand value of the top global brands from the years 2000-2018. As the animation plays out each brand's bar on the chart grows or shrinks to reflect the brand's value. The bars also re-sort themselves automatically to show the most valuable brand at the top and the least valuable brand at the bottom. If a brand falls out of the top twelve most valuable brands then it falls off the bar graph. This method of visualization is very effective in showing the sudden rise or sudden fall in the value of a brand in comparison to the world's other large brands and the performance of these brands over time.

John Murdoch has now released another impressive animated bar race. This one shows The Most Populous Cities in the World from 1500 to 2018. This bar chart race is an incredibly interesting visualization of the world's most populated cities. There is something hypnotically fascinating watching different cities move up and down the chart over time as their populations rise and fall in comparison to other cities around the world. The bar chart is accompanied by a map which shows the location of the currently displayed most populated cities. Each city's bar on the chart is also colored by global region. The colors on the chart and the map help to reveal any regional patterns in the relative rise and fall of city populations.

As fantastic as John's visualization is I hope that there is more to come. I'd love a date control so that I could manually navigate to view the most populated cities in specific years. I'd also love some historical commentary with the visualization to provide some context or explanation as to why different cities rise or fall in the visualization. For example, when the visualization starts in 1500 Vijayanagar is the second most populous city in the world. It then suddenly drops off the chart in 1565. According to Wikipedia "In 1565 ... the city fell to a coalition of Muslim Sultanates. The conquered capital city of Vijayanagara was looted and destroyed, after which it remained in ruins.". An annotated version of The Most Populous Cities in the World would keep me happy for days.

As it is The Most Populous Cities in the World is totally awesome. What is even better is that it has been built and released as an Observable Notebook. That means anyone can fork, use and adapt the code. If you click on the 'dataset' line in the code you can see how the data for the visualization is formatted and click through to view the csv file where the data is held. This means that it would be a relatively trivial matter to adapt the visualization to work with your own data. Therefore you could create your own bar chart race, for example to show the most populated countries in the world over time or to show the most populated cities in your country over time. You could use economic data to show the GDP per capita of cities or countries over time. You could show the average life of death in cities or countries over time. In fact the bar chart race method is a great way to visualize lots of different types of data that has a time element.

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