Category: General

‘Worst Sankey Diagram’ Award Suggested

Following my last post, which led to quite a number of comments, one reader of this blog has suggested to create a ‘Worst Sankey Diagram’ award.

While I personally kind of like the idea, I am not sure whether we can find as many ‘bad’ Sankey diagrams, in order to make this a real competition… Wouldn’t a ‘Best Sankey Diagram’ award be more reasonable? This is what I am going after in my search for Sankey diagrams, that I can present here on the blog. After all I want to show how useful and powerful this type of diagram is for specific visualizations.

Infographics Experts on Sankey Diagrams (Part 2)

Following yesterday’s post with the translation of a blog post by Chiqui Esteban from infografistas.com here is the translation of the post “Caudales, erogación… ¿flujo?” of April 5, 2009. Again, I left some words in Spanish in square brackets.

— translation start —

Volume flow, distribution… flux?

A new chapter in the discussion [polémica] about the ‘scientific’ name of the “little arms” graphics [‘gráficos de bracitos’].

Xocas came up with the name ‘volume flow’ diagrams [‘gráficos de caudales’] and my vote was for ‘distribution diagram’. Other suggestions were thrown in: Xoán G. made reference to Minard and his ‘capacity diagram’ [‘gráfico de aforo’]. Herminio J. Fernández voted for cosmography diagrams [‘cosmografías’] as refered to by Stovall [Infographics by James Glenn Stovall, Allyn&Bacon, Massachussetts, 1997]. Many others voted for ‘flow diagrams’ [‘gráficos de flujo’], although Xocas discarded this suggestion because “the term flow diagram normally refers to a very specific type of visualization of process [flows]. It could be used as a generic term, but has interference with another model”.

Now, there is a new player in our conversation. It is Mario Tascón, who also believes that the correct denomination is ‘flow diagrams’. His justification:
“According to Harris (Information Graphics) and Bruce Robertson (How to make Charts and Diagrams) these graphics are called flow diagrams, and are of the type in the same category which are used as decision diagrams in informatics [computer science]. The latter are more in fashion now [Por motivos de modas], but the former have always [sic!] existed (a historic example is the one of Napoleons troops)”.

Suggestions are welcome in the comments.

— translation end —

I hope I got it more or less correct. It is not easy to find the right translation for the sometimes subtle differences between the terms. For those of you who can read Spanish, please check out the original post and the full discussion thread on Xocas’ blog.

The post is decorated with this beautiful Sankey diagram.

It shows the main earnings and spendings of Spain in 2008 and was produced by Jorge Doneiger and Álvaro Valiño for the daily newspaper Publico in 2007. Values are in million Euros. Flows are not always to scale as for as I can see: the ‘impuestos especiales’ in dark black and the ‘deuda pública’ (at the bottom on the right side) are examples.

The top part shows the sources of funding, the bottom part the beneficiary sectors. The fact that the stacked width in the middle is wider than that of the funds distributed suggests that the Spanish state is actually piling up its money, but probably this has to do either with the list of recipients not being complete, or with earnings received in 2008 but not distributed in the same year.

The hand with the coin supports Chiqui Esteban’s vote for naming it a ‘distribution diagram’. Toss a coin in the coffee dispenser and wait for your coffee to be poured… errh, did we have ‘dispenser diagram’ already? 😉

I save the ‘best of comments’ and my reasoning why I still call them Sankey diagrams for another time…

Note (Aug 19): A case of DYRF, do your research first! I just detected that Chiqui himself has an English version of his article here. So, now you got the choice between two versions!

Infographics Experts on Sankey Diagrams (Part 1)

Chiqui Esteban who runs the Spanish blog infografistas.com had two posts back in March/April about a discussion he had with his colleague Xocas on how to name Sankey diagrams. Or, to be more precise: how a certain type of diagram that is more and more used in infographics should be named correctly.

They are absolutely funny, so I am trying to give you a translation of these two blog posts. This is part 1 for a post from March 17 titled “Gráficos de erogación”. I left some words in Spanish and my comments in square brackets.

— translation start —

Distribution Graphics

A couple of months ago, Xocas and I discussed via GTalk what the name, or what should be the name of the diagrams with the little arms [‘gráficos de bracitos’]. As it turned out, the winner name was volume flow graphics [‘gráfico de caudales’].

Today, we decided to withdraw our proposal and we are going to call them ‘distribution graphics’ instead [‘gráficos de erogación’].

This is because of the coffee. The coffee machine of my new employer www.lainformacion.com (click the link, we are already up running), shows the message ‘distributing’ [‘erogando’] while you wait for your cup to be filled. Looking in the RAE [note: Real Academia Española], the verb ‘erogar’ is defined as:

(Del lat. erogāre).

1. tr. Distribuir, repartir bienes o caudales. [distribute, share the goods or funds]
2. tr. Méx. y Ven. Gastar el dinero. [México and Venezuela: spend money]

This definition is spot on. So we shouldn’t continue to call them ‘little arms’ [‘de bracitos’], ‘tubing’ [‘de tubería’], ‘squid’ [‘de pulpo’], ‘tree-roots’ [‘raíces’] or whatever diagrams any more. But don’t say that we didn’t work hard in finding the correct nomenclature. As we have to do. So Tufte will… [‘A Tuftear’].

— translation end —

The accompanying Sankey diagram apparently is from the New York Times and shows how 21.4 billion $ in federal aid for NYC after 9/11 were distributed (hey! there you are, a ‘distribution diagram’ 😉 ). Funny enough, the caption says: “The figure above is an attempt to bring sources of funds together and show how they add up (sic!) to $ 21.3 billion”.

So what is distribution for one, is “adding up” from another perspective.

Part 2, the translation of “Caudales, erogación… ¿flujo?” and a summary of the comments to follow.

Note (Aug 19): A case of DYRF, do your research first! I just detected that Chiqui himself has an English version of his article here. So, now you got the choice between two versions!

Matlab routine for simple Sankey diagrams

Just came across a new piece of software for simple Sankey diagrams.
DrawSankey.m is a routine for Matlab that allows to produce diagrams like these:

DrawSankey.m is from the Industrial Energy Systems Laboratory (LENI) at Swiss EPFL in Lausanne. Find more information on their Wiki.

I haven’t tested it myself yet, but this definitely looks like an interesting add-on for Matlab users. I have added drawSankey.m to the Sankey software list.

What goes up, must come down!

For most Sankey diagrams I find when browsing the web, a ‘left-to-right’ or ‘bottom-to-top’ orientation prevails. ‘Top-to-bottom’ is less common, but there are also examples like this one.

A rather untypical shape for a Sankey diagram has been up on the German page of the e!Sankey webpage.

It shows the energy balance for a pumped storage power plant as a curved shape, with the energy input at the left leg, and the energy that can be recovered (77.3%) at the right one.

Energy is stored “in the form of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost off-peak electric power is used to run the pumps. During periods of high electrical demand, the stored water is released through turbines. Although the losses of the pumping process makes the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest. Pumped storage is the largest-capacity form of grid energy storage now available.” (Wikipedia)

I searched for the original Sankey diagram in the source given (Quaschning 2007) and found this text with the diagram in chapter 6.1.2. That diagram already featured the curvy shape, and has just been reproduced similarly.

The use of the curve layout seems justified here. The author chose it to point out the difference in altitude. The upper basin is at the apex of the curve. Water pumped up from the lower basin requires energy, which can partly be recovered when the water runs down again.

What goes up…