A table set for fasting

Hi, this is Rose. I write for Datawrapper’s blog — and this week I’m back for a holiday Weekly Chart.

If you look at this year’s Weekly Chart archive, you might get a strange impression of what holidays are celebrated in our office. The spring equinox: a pretty big deal to the ancient Maya, as Anna explained, and it still gets one post today. Christmas: an actual legal holiday in Berlin, and we wrote two posts about it. National election: now that’s a real holiday as far as data vis is concerned. We gave it three posts.

So this week, let’s take a break from the news to celebrate Ramadan! Since last Saturday, Muslims around the world have been observing the monthlong holiday, whose major aspect is a complete fast during daylight hours. A few days ago, I happened upon this neat chart from the Economist, which compares the hours of the fast in ten countries with the biggest Muslim populations. That chart was published in 2015, when Ramadan began on June 18. Because it follows the lunar calendar, Ramadan falls on a different solar date from year to year — which means that the length of the daytime fast also changes from year to year. So I decided to create my own updated version of the chart for 2022:

Since days in the Northern Hemisphere are still lengthening, the fast will get a little longer here every day — the area in light orange represents those extra hours, which only fall during the fast towards the end of the holiday. For this table, I calculated each country's daylight hours using the coordinates of its largest city. You can see that in cities near the equator (like Jakarta, Indonesia) the fast will stay pretty much the same throughout the month. In fact, none of these countries is too far from the equator; Muslims in all of them will fast for similar lengths of time. Meanwhile, in Greenland...

The farther north you go, the longer the day will be: a person in Greenland can look forward to fasting over 18 and half hours by the end of the holiday. In the Southern Hemisphere, meanwhile, the day is getting shorter: in Auckland, New Zealand, last weekend's 13-hour fast will shrink to just under 12 hours by May. This year, with Ramadan falling near the equinox, no one has it too rough — when the holiday falls near the summer solstice, some Muslims in far northern areas observe Mecca's fast times to avoid going without food and water for over 22 hours.

Tips for creating this chart

The chart that inspired me doesn't particularly look like a table. But I knew that a Datawrapper heatmap was the perfect tool to recreate it.

Any numeric column in a Datawrapper table can easily be turned into a heatmap. But the data here is categorical — any given time slot is either day, night, or in-between. Not a problem: I simply recoded those columns as numbers, using 0 to represent nighttime and 1 to represent day. Using a table (instead of some other option like stacked bars) also allows me to show each country's total Muslim population with mini bar charts.

You can hover over any chart in this post and click on “Edit this chart” in the top right corner to get your own copy to edit and play around with. For an explanation of how to create a heatmap yourself, head over to our Academy.

That's all from me for this week. Ramadan mubarak to everyone celebrating!