# Month: September 2011

## Misc Sankey Diagrams Uncommented 04

Found these two Sankey diagram on Wikiversity. I think it was somewhere on one of the sub-pages on the small solar vehicle… They show energy losses at the different components of the vehicle, such as at the solar panels or through rolling resistance. Percentage values.

These diagrams are made up from rectangles and simple arrows. Only straight arrows, no curves. The blue color of the border of some of the thinner arrows adds a strange effect…

## Making Of an Infographic

A notice on scoop.it/visualdata led me to this fascinating video on visualnews. It shows the making of an infographic in two minutes or 3657 frames and is by Jess Bachmann for mint.com.

The central element of the infographic is a Sankey diagram on the trade flows between the United States and China (and to/from other countries).

it is interesting to see how Jess did every weighted arrow as a brush line with rounded head (the heads are neatly hidden behind the country maps, or capped at the other end). Each horizontal, vertical and curved segment is done individually.

In the YouTube comments of the long version of this video the author replied to one commenter: “After determining a metric, i.e 1 pixel width = \$1M, I then stroked a line with the corresponding size brush. A \$34M﻿ item would have a 34px width line. At one point you can even see a calculator popping up (0:55 into the video).

The long (7 minute) version has a lot more details on how the infographic comes to life. You can even see that Jess keeps saving his work from time to time…

Wow, what a hell lot of work – but the result sure looks gorgeous.

I calculated that Jess took more than 10h to complete this: 3657 frames, ten seconds between each frame = 36570 sec, 3600 seconds to an hour, makes 10.16 hours! I am just glad I have my Sankey diagramming software, so at least I don’t have to bother about brush sizes.

## Sankey Diagrams in Python

I am impressed by the Sankey diagrams produced with ‘sankeypython’, a new open source project. I first came across this in a discussion forum, where Yannick Copin from France presented his work using matprotlib. The project is now at Sourceforge. This sourceforge link not working any more, check Matplotlib project instead (thanks to commenter Johannes for pointing out the broken link), and several Sankey Diagrams in Python samples can be seen there.

The most important functionality is available, such as labels for flows and units. Diagrams have a basic left-to-right orientation, with vertical arrows branching out on both sides. Color changes seem to be realized by combining several systems. There are apparently no node objects where the flows directly hook to (as is common in other tools), but by interlacing differently colored Sankey arrows a process step becomes kind of implicit.

This has only been up on Sourceforge since June 2011, so it will be interesting to follow further development on ‘Sankey Diagrams in Python’. I have added the project to the list of Sankey diagram software.

## Engine Combined Cycle Power Plant Sankey

At the Technical University of Munich a project on Engine Combined Cycle (ECC) Power Plants aims at “improving the electrical efficiency of an engine combined cycle plant by using the exhaust gas heat in a steam cycle”.

The following Sankey diagram is shown to illustrate where heat can be recovered.

No absolute values are given, but the Sankey arrows represent the percentage of the primary energy. Four percent of the energy in the steam process can be recovered to add a total of 47.8% efficiency output of electrical power to grid. Losses branch out to the right side and are primarily via the cooling water and condensate at the steam process. The whole Sankey diagram is presented in a simple single-color design.

## Efficient Water Use in Saudi-Arabia

Consumption of water resources in arid and semi-arid areas has become an important issue over the last years. The Wafeer water conservation project is trying to raise awareness and educate people in Saudi-Arabian industry in regard to the efficient use of water. On page 21 of their Water Efficiency Manual, the following Sankey diagram can be found:

The report describes that “Sankey diagrams enable visual representation of both quantitative and qualitative characteristics of water entering and leaving different activities and therefore serve as a good communication aid.”

The above diagram does not show any unit, but presumably is meant to be in cubic metres (per year?). It shows water (blue) and waste water (grey) flows, as well as evaporation losses (red).

More water Sankey diagrams of similar style can be found on pages 19 through 23 in this workshop presentation on ‘The Importance of and Difficulties in Water Accounting’.

## Misc Sankey Diagrams Uncommented 03

From the Mostly Uncommented Series, here is another one that has been sitting in my collection.

Black/White Sankey diagram for energy gains and losses in a building. Titles in French. Shadow effects. No values given. Unnecessary crossing of Sankey arrows. Not sure where I downloaded this from, will have to check my bookmarks. In the meantime, pls have a nice week-end…