2 notes on data visualization

Written on 9 October 2019, 09:37pm

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  1. Know the limitations of pie charts: not so good for comparing values between themselves, but really good to compare relative to the 50% line
  2. Match your type of data with the right color scheme. There are 3 types of data: sequential, divergent and qualitative. The sequential color schemes help with ordered data. The divergent schemes use a neutral color the mid-range data and highly contrasting colors for the extremes. The qualitative schemes focus on creating visual differences between the sets of data.
Bar charts are better if you need to compare the values
But pie charts have their strengths when comparing to the 50% line
A sequential scheme. Colors range from light to dark, and are usually colorblind safe
A diverging scheme. Mid-range neutral color, highly contrasting extremes.
A qualitative, colorblind-safe scheme. It gets trickier if you need more than 4 colors. Each color need to scream “I’m different!

https://www.data-to-viz.com/caveat/pie.html
https://www.perceptualedge.com/articles/visual_business_intelligence/save_the_pies_for_dessert.pdf

http://colorbrewer2.org

Random links #17

Written on 7 October 2019, 02:49pm

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Electric planes

Air travel is bad for the planet—and travelers may finally be getting the message.
The change in mindset is due to increasing awareness of the issue thanks to attention-grabbing protests, like when activist group Extinction Rebellion shut down Heathrow Airport and climate warrior Greta Thunberg sailed across the Atlantic in a zero-emissions yacht to speak at the UN’s climate summit.

Does flight shaming work?

Solution? Hybrid or full electric planes. Also tested by NASA.

Heavyside, from Kitty Hawk is really silent and has a range of about 100 miles

Radiation in space is a big deal

If we want to prepare astronauts to fly to Mars, then we have a lot of problems to solve when it comes to health and well being. There are both psychological (isolation, confinement, sleep disturbance, etc) but also physiological (micro-gravity long time effects, radiation) factors to overcome. One of the most important is the radiation.

Radiation on Earth is about 4.6 mSv/year. On the Moon – 300/400x. On Mars – 1000x.

How can we reduce the radiation impact? Medical selection of the most resistant individuals, shielding (the ISS has 3 highly shielded areas) and medication. Hibernation is also an option, not explored yet.

Radiation sensitivity decreases with age. A teenager is 2 times more sensitive than a 30-years old adult, which is in turn 2 times more sensitive than a 50-years old.

Space travel affects the astronauts’ immune system. Various factors play a part in this process, i.e. weightlessness, cosmic radiation, isolation and the inevitable stress. At the request of European, American and Russian space agencies, SCK•CEN tests the blood of astronauts when they return from a long space mission. We perform analyses using advanced biochemical and molecular techniques.
Long-term exposure cannot be avoided during long distance missions, e.g. to Mars – for which the return flight takes 18 months. Sensitivity to cosmic radiation varies considerably between people, and consequently also between astronauts. 

The Belgian Nuclear Research Centre

Time matters

The Tesla dashcam writes its rolling clips in the /recent folder. The manually saved clips are stored in the /saved folder. Recently Tesla introduced the Sentry mode, which automatically saves events when the car is parked (ex. a person or a car is passing by).

The Tesla engineers thought that it’s appropriate to save these clips not in a dedicated folder (like /sentry), but in the same /saved folder where the manual clips are saved.

The outcome? When I want to look for a video that I manually saved, I have no easy way to find it. Sentry mode produces a huge number of videos, sometimes 10 videos for a half an hour spent in a busy parking. Finding the right folder among literally hundreds of other folders is like finding a needle in a haystack.

Compare this to the following bit:

One day Jobs complained to Larry Kenyon (the engineer of the Macintosh OS) that it was taking too long to boot up. Kenyon explained why reducing the boot-up time wasn’t possible, but Jobs cut him off: “If it would save a person’s life, could you find a way to shave 10 seconds off the boot time?”. He then showed on a whiteboard that if the Mac had five million users and it took 10 seconds extra to turn it on every day, that added up to 300 million or so hours a year — the equivalent of at least 100 lifetimes a year. After a few weeks, Kenyon had the machine booting up 28 seconds faster.

Steve Jobs Insane Productivity Secrets

Digital revolutions happening under our eyes

Written on 1 October 2019, 04:48pm

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In the beginning, there was the internet.

Then Steve gave us the smartphone and put the internet in our pockets, along with the thousands of apps to entertain us and crush the candies.

Soon after, Facebook and Twitter started to connect us. We liked it, and later on, Instagram and WhatsApp took off and filled the social media gap.

Then it was time to Netflix and chill. The streaming services filled our TVs with movies and our headphones with music and podcasts. Out of the pirate bay.

Without even realizing, during this time Amazon removed the friction in the online shopping. Same day delivery became the norm and the Black Fridays + Prime Days changed the expectations about shopping deals.

Changing the way we move and travel took a bit more time. But once we got Uber and Airbnb, there was no going back. UberEats, the electric bikes and scooters were really inevitable.

Workplaces had to keep up, and so remote work, co-working spaces and hot-desking became more and more familiar.

Now we leave in a world where we can have a nomad life. We no longer own a place, but we explore the world and jump from one AirBnb to another using Uber. If we want to drive, we DriveNow. We can work from anywhere and get paid directly in our Revolut account. We ride a Lime to the nearest grocery store where we pay with our phone. When we go out running, we use our wearables to see how we did and share the results with the world. We go out after swiping left and right, and there’s a 2/3 chance to meet our significant other online rather than in real life. When we are tired, we use UberEats to order pizza and take the couch to binge the most popular Netflix show.

Welcome to 2019! 🤩