Sankey diagram

Sankey diagrams are a data visualisation technique or flow diagram that emphasizes flow/movement/change from one state to another or one time to another,{{cite journal | author-first1 = Ethan | author-last1 = Otto | author-first2 = Eva | author-last2 = Culakova | author-first3 = Sixu | author-last3 = Meng | author-first4 = Zhihong | author-last4 = Zhang | author-first5 = Huiwen | author-last5 = Xu | author-first6 = Supriya | author-last6 = Mohile | author-first7 = Marie | author-last7 = Flannery | date = 2022-05-13 | title = Overview of Sankey Flow Diagrams: Focusing on Symptom Trajectories in Older Adults with Advanced Cancer | journal = Journal of Geriatric Oncology | volume = 13 | issue = 5 | pages = 742–746 | doi = 10.1016/j.jgo.2021.12.017 | pmid = 35000890 | pmc = 9232856 }} in which the width of the arrows is proportional to the flow rate of the depicted extensive property. The arrows being connected are called nodes and the connections are called links.

Sankey diagrams can also visualize the energy accounts, material flow accounts on a regional or national level, and cost breakdowns.{{cite journal | last = Schmidt | first = Mario | date = 2008 | title = The Sankey Diagram in Energy and Material Flow Management - Part II: Methodology and Current Applications | journal = Journal of Industrial Ecology | volume = 12 | issue = 2 | issn = 1530-9290 | pages = 173–185 | doi = 10.1111/j.1530-9290.2008.00015.x }} The diagrams are often used in the visualization of material flow analysis.

Sankey diagrams emphasize the major transfers or flows within a system. They help locate the most important contributions to a flow. They often show conserved quantities within defined system boundaries.

History

Sankey diagrams are named after Irish Captain Matthew Henry Phineas Riall Sankey, who used this type of diagram in 1898 in a classic figure{{cite journal | last1 = Kennedy | first1 = Alex B. W. | last2 = Sankey | first2 = H. Riall | date = 1898 | title = The Thermal Efficiency Of Steam Engines | journal = Minutes of the Proceedings of the Institution of Civil Engineers | volume = 134 | issue = 1898 | pages = 278–312 | doi = 10.1680/imotp.1898.19100 | url = https://zenodo.org/record/2036163 }} (see diagram) showing the energy efficiency of a steam engine. The original charts in black and white displayed just one type of flow (e.g. steam); using colors for different types of flows lets the diagram express additional variables.

Over time, it became a standard model used in science and engineering to represent heat balance, energy flows, material flows, and since the 1990s this visual model has been used in life-cycle assessment of products.{{cite journal | last = Schmidt | first = Mario | date = 2008 | title = The Sankey Diagram in Energy and Material Flow Management - Part I: History | journal = Journal of Industrial Ecology | volume = 12 | issue = 1 | pages = 82–94 | doi = 10.1111/j.1530-9290.2008.00004.x | s2cid = 154150190 | doi-access = free }}

File:Minard.png's invasion of Russia, using the feature now named after Sankey]]

One of the most famous Sankey diagrams is Charles Minard's Map of Napoleon's Russian Campaign of 1812.{{cite web|last1=Corbett|first1=John|title=Charles Joseph Minard: Mapping Napoleon's March, 1861|url=http://www.csiss.org/classics/content/58|publisher=Center for Spatially Integrated Social Science|access-date=21 May 2023|archive-url=https://web.archive.org/web/20170312205811/http://www.csiss.org/classics/content/58/|archive-date=12 March 2017|url-status=dead}} It is a flow map, overlaying a Sankey diagram onto a geographical map. It was created in 1869, predating Sankey's first Sankey diagram of 1898. Minard had used this form of diagram for visualising flow of goods and transport of people from at least since 1844.{{cite web | url=https://catalogue.bnf.fr/ark:/12148/cb46641873t | title=Tableaux graphiques et cartes figuratives. : [transports de voyageurs et marchandises en France et Europe, trains, péniches, navires, transports maritimes mondiaux, importations de coton, de houilles 1845-1870] | date=1844 }}

Science

File:Earth_heat_balance_Sankey_diagram.svg – line thickness is linearly proportional to relative amount of energy]]

Sankey diagrams are often used in fields of science, especially physics. They are used to represent energy inputs, useful output, and wasted output.

Active examples

The United States Energy Information Administration (EIA) produces numerous Sankey diagrams annually in its Annual Energy Review{{cite web|title=Annual Energy Review|url=http://www.eia.gov/totalenergy/data/annual/|website=Energy Information Administration|access-date=15 December 2017}} which illustrate the production and consumption of various forms of energy.

The US Department of Energy's Lawrence Livermore Laboratory maintains a site of Sankey diagrams, including US energy flow and carbon flow.{{cite web|title=LLNL Flow Charts|url=https://flowcharts.llnl.gov/|website=Lawrence Livermore National Laboratory|access-date=15 December 2017}}

Eurostat, the Statistical Office of the European Union, has developed an interactive Sankey web tool to visualise energy data by means of flow diagrams.{{cite web|title=Energy balance flow for European Union (28 countries) 2015|url=http://ec.europa.eu/eurostat/cache/sankey/sankey.html?geo=EU28&year=2015&unit=KTOE&fuels=0000&highlight=&nodeDisagg=0101000000&flowDisagg=false|website=Eurostat|access-date=15 December 2017}} The tool allows the building and customisation of diagrams by playing with different options (country, year, fuel, level of detail).

The International Energy Agency (IEA) created an interactive Sankey web application that details the flow of energy for the entire planet.{{cite web|title=World Balance (2015)|url=http://www.iea.org/Sankey/#?c=World&s=Balance|website=International Energy Agency (IEA)|access-date=15 December 2017}} Users can select specific countries, points of time back to 1973, and modify the arrangement of various flows within the Sankey diagram.

File:Balance of trade with the United States by country.webp (2023)]]

References

External links

{{commons category-inline|Sankey diagrams}}

Category:Diagrams

Category:Irish inventions

Category:British inventions