Monthly Archives: October 2019

October 29, 2019 · 5:13 pm

Barcelona trees

Here I am again, this time with something that I love, trees!

It’s mostly common knowledge that the tree of Barcelona is the Platanus (bear with me with tree names, since the names in english confuse me most of the time 🙂 ). I’ve been looking for an excuse to dive back to Barcelona open data, and to create a hex-grid-map.

For this two images, I’ve used the street trees dataset, which only takes into account trees planted along streets, parks and green zones are not taken into account.

And from this excuse, two new data visualizations emerged!

show me those trees

Barcelona traffic accidents 2018

Coat of Arms Barcelona

Following the quick map of Barcelona mean renting prices, I took it to play a little bit more with datasets of Barcelona.

I came across an interesting one, traffic accidents in Barcelona, which could map quite nicely as a Heatmap:

Unsurprisingly there are accidents all over Barcelona, but the city center concentrates the highest amount of them.

The dataset splits the accidents by accident type (alcohol, bad signs etc), but the majority of points are classified as Not provided so there’s no way to prepare more specific maps.

There are datasets from 2014 upwards, to be frank, after checking them the hot points are more or less the same, so 2018 is probably enough to get an idea 🙂

Some extra fun (vehicle type)

I had some extra fun playing with this datasets, I filtered by different vehicle types to generate different heatmaps.

Buses are all over the place (which make sense, since those are running almost non-stop all over the city). On the other hand, Taxis are quite focused in the city center and l’Eixample, not surprising those being the most traffic packed zones.

Personal car accidents appear in the city center too, but we can see some highlights in the two arteries of the city, ronda de dalt and ronda litoral, those motorways are the main way to cross Barcelona connecting to bigger highways and neighbouring cities. There are daily jams in those two motorways.

Bike accidents appear mainly in the center, eixample and close to wide streets (like Diagonal and Meridiana). In other neigbourhoods it looks quite safe 🙂

Some extra fun (vehicle color)

Find here a clunky non-stylized bar graph of total accidents by vehicle colours. Colour names are in catalan, but the bars match the name so it’s quite international. Yes, apparently there’s a category for black-yellow vehicles, which I guess are Taxis.

What about the insurance myth about red cars?. Well, I don’t know about that, but it’s clear that there’s a big bar of red vehicles having accidents 🙂 But since I don’t have the number of red cars running around Barcelona it could just be that it’s a popular colour. White and Black cars are very common (from a quick walk around in Bcn you confirm that statement) and as you can see those have the most accidents.

To be safe, just buy a pink car 😉 (not really)

Conclusion

Making smallish maps of my area is fun, so I might get more datasets to present different aspects of Barcelona in the future :-D.

References

Barcelona Series

Barcelona rent price

2 Comments

Filed under curious, Life, Maps

Tagged as accidents, barcelona, bcn_opendata, life, maps, qgis

October 1, 2019 · 3:45 pm

Flattening the Earth: Two Thousand Years of Map Projections

This book can be summarized by: Excellent text about projections, also a very dry read.

I understand the aim of it, more of a history on map projections, the importance of them on a given period of time, and what they brought to the table.

As a scholar text it is really complete and thorough (there’s up to 35 pages of referenced works). As something to read from beginning to end it is quite boring. It’s better to read bit by bit when you feel like it. And be ready to concentrate on the contents, otherwise most of what it tries to tell you will just go over your head.

The book contents are plain but beautiful, full renderings of different map projections help give you an overview on how older maps were built. But at the same time I miss some real scans of old maps where we can see those projections in use. Being a history book would be really nice to present both a rendering alongside a real scan. The few cases where a scan is next to the rendering provide a good context to the projection.

Can’t finish this without commenting about fun excerpts of old descriptions of the projections, for example Ptolemy‘s take on his favourite projection:

(…) Although for these reasons this method of drawing the map is the better one, yet it is less satisfactory in this respect, that it is not as simple as the other…. for me both here and everywhere the better and more difficult scheme is preferable to the one which is poorer and easier, yet both methods are to me retained for the sake of those who, through laziness, are drawn to that certain easier method (…)

— Translation From Stevension 1932,

Full projections are described using this really old language as an example on how the knowledge was passed along before modern mathematics. Luckily, alognside those there’s a description from the author (John P. Synder) which makes everything much clearer.

Not a book I would recommend to everyone, but a really cool book to have in your bookshelf for some short bursts of reading.

Note

I did not finish reading this book yet. I’ve read the renaissance projections chapter and skimmed the nineteenth century projections chapter. (2 of 4 total chapters). Missing chapters on 1670-1799 and the twentieth century.