Martin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca Martin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca - contact me Martin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca on Twitter Martin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca - Lumondo Photography Martin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca - Pi Art Martin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca - Hilbertonians - Creatures on the Hilbert CurveMartin Krzywinski / Canada's Michael Smith Genome Sciences Centre / mkweb.bcgsc.ca - Pi Day 2020 - Piku
Without an after or a when.Papercut feat. Maiken Sundbycan you hear the rain?more quotes

constellations: worthwhile


Scientific graphical abstracts — design guidelines


visualization + design


`\pi` Day 2021 Art Posters - A forest of Pi (a Lindenmayer system)
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca buy artwork
81 digits of `\pi` as a forest of trees: standard, bat cave and underwater editions. ( BUY ARTWORK )
Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
The 2021 Pi Day art celebrates the digits of `\pi` with a forest! Visit the bat cave and underwater ecosystems for the full experience.

`\pi` Day 2017 Art Posters - Star charts and extinct animals and plants


Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2021 `\pi` reminds us that good things grow for those who wait.' edition.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2019 `\pi` has hundreds of digits, hundreds of languages and a special kids' edition.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2018 `\pi` day stitches street maps into new destinations.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2017 `\pi` day imagines the sky in a new way.


Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2016 `\pi` approximation day wonders what would happen if about right was right.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2016 `\pi` day sees digits really fall for each other.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2015 `\pi` day maps transcendentally.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2014 `\pi` approx day spirals into roughness.


Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2014 `\pi` day hypnotizes you into looking.

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2014 `\pi` day

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
2013 `\pi` day is where it started

Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Circular `\pi` art and other distractions

On March 14th celebrate `\pi` Day. Hug `\pi`—find a way to do it.

For those who favour `\tau=2\pi` will have to postpone celebrations until July 26th. That's what you get for thinking that `\pi` is wrong. I sympathize with this position and have `\tau` day art too!

If you're not into details, you may opt to party on July 22nd, which is `\pi` approximation day (`\pi` ≈ 22/7). It's 20% more accurate that the official `\pi` day!

Finally, if you believe that `\pi = 3`, you should read why `\pi` is not equal to 3.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Most of the art is available for purchase as framed prints and, yes, even pillows. Sleep's never been more important — I take custom requests.

Caelum non animum mutant qui trans mare currunt.
—Horace

This year: creatures that don't exist, but once did, in the skies.

This year's `\pi` day song is Exploration by Karminsky Experience Inc. Why? Because "you never know what you'll find on an exploration".

If you like space, you'll love my the 12,000 billion light-year map of clusters, superclusters and voids. Find the biggest nothings in Boötes and Eridanus.

create myths and contribute!

Want to contribute to the mythology behind the constellations in the `\pi` in the sky? Many already have a story, but others still need one. Please submit your stories!

Here I make available all the files you need to reconstruct the chart. All files are plain text and designed to be easily parsable.


Pi Day 2017 Art Posters - Star charts and extinct animals and plants
 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca buy artwork
Star chart of the first 12,000,000 digits of `\pi`. The 80 constellations honor extinct animals and plants. Azimuthal equidistant projection. ( BUY ARTWORK )

For the simplest chart, you'll need the star catalogue which already provides the longitude and latitude coordinates for each star. It'll be up to you to choose and calculate a projection.

You can then layer constellations, which are defined by a list of edges. If you like, you can draw boundaries around each constellation, which are also provided.

Star-to-constellation mapping is also given, which allows you to create labels for the stars within each constellation based on relative brightness.

Finally, you can get the species details for each constellation, including the Latin name of the species, Wikipedia URL and (for many) the mythology of the constellation.

star catalogue

The star catalog generated from the first 12 million digits of `\pi`.

DOWNLOAD

#   idx       digits   name      x      y      z     long      lat      dist  mabs  mapp
      0 314159265358      a  -1859    926     35  145.339   38.384  2077.157  3.00 14.59
      1 979323846264      b   4793  -2616    126  -38.404  -39.555  5461.884 -1.00 12.69
      2 338327950288      c  -1617  -2205   -472 -110.162   32.164  2774.797  3.00 15.22
      3 419716939937      d   -803  -3307    493 -105.489    3.655  3438.620  2.00 14.68
...
 999996 601538500580  cexhk   1015  -1150   -442  -48.144  -14.704  1596.273 -5.00  6.02
 999997 420478142596  cexhl   -796   2814   -241   97.939   14.471  2934.330  1.00 13.34
 999998 278256213419  cexhm  -2218    621   -159  156.900   46.719  2308.776  4.00 15.82
 999999 453839371943  cexhn   -462  -1063   -306  -95.924   26.937  1198.770 -2.00  8.39

constellation definitions

Constellations were manually defined. Each constellation has a name and abbreviation (first 3 characters unless longer is required to uniquely specify it). Shown next is the number of stars used to define the constellation and their names, as appear in the star catalogue file above. Next is the number of edges and the star pairs that define the edges of the constellation. The edges are not in any particular order and have no direction. Any spaces in names are encoded with _.

DOWNLOAD

# idx n_stars n_edges name abbrev stars edges
 ...
 2  3  3                   alaotra     ala blts,btosf,cbkbw btosf-cbkbw,blts-btosf,blts-cbkbw
 3  4  4                 alloperla     all ghyr,pwkn,ssrx,ugwt pwkn-ssrx,pwkn-ghyr,ugwt-pwkn,ssrx-ghyr
 4  2  1                   aplonis     apl cbocd,rllm rllm-cbocd
 ...

You can use this file to quickly search for certain shapes. For example, triangular constellations are those that have 3 stars and 3 edges.

> grep " 3  3" constellations.def.txt
 2  3  3                   alaotra     ala blts,btosf,cbkbw btosf-cbkbw,blts-btosf,blts-cbkbw
16  3  3                   camptor    camp benxf,bqvh,bwqed bqvh-benxf,bwqed-bqvh,bwqed-benxf
26  3  3                  desmodus     des bfnqu,mork,zwzy bfnqu-mork,zwzy-bfnqu,zwzy-mork
27  3  3                ectopistes     ect bopmt,cbquf,wmnw cbquf-bopmt,wmnw-cbquf,wmnw-bopmt
30  3  3                    hoopoe     hoo bpsop,bvmjh,tryh tryh-bvmjh,bpsop-tryh,bpsop-bvmjh
31  3  3                      huia     hui ccteo,xbvq,yqet xbvq-yqet,ccteo-xbvq,ccteo-yqet
39  3  3               malpaisomys     mal bucqd,likq,nqn nqn-bucqd,likq-nqn,likq-bucqd
41  3  3                   mariana     mar gmps,jydb,pcjx pcjx-gmps,jydb-pcjx,jydb-gmps
49  3  3          palaeoaldrovanda     pal bedae,oife,saz bedae-saz,oife-bedae,oife-saz
63  3  3                    rhynia     rhy bpviv,cenuk,hivz bpviv-hivz,cenuk-bpviv,cenuk-hivz
65  3  3                  silphium     sil bjesg,bmquw,bpxia bmquw-bpxia,bjesg-bmquw,bjesg-bpxia
69  3  3                   tadorna     tad bukqe,cbtrx,epdx cbtrx-epdx,bukqe-cbtrx,bukqe-epdx
72  3  3                 traversia     tra fcnw,fywb,puib fywb-fcnw,puib-fywb,puib-fcnw
80  3  3                  yersinia     yer colq,ibls,zgvy ibls-zgvy,colq-ibls,colq-zgvy

constellation boundaries

The boundaries were manually defined. Shown here, for each constellation, is the constellation's area, perimeter center and boundary `(x,y)` pairs, delimited by : and represent a closed polygon that encloses the constellation's stars.

All values are longitude and latitude. The three constellations listed below are ones with smallest area.

DOWNLOAD

# abbrev area perimeter centroid_xy boundary_xy_pairs

...
com 74.83 34.96 -102.50,26.25 -100.00,30.00:-102.50,30.00:-105.00,30.00:-107.50,30.00:-107.50,27.50:
			      -107.50,25.00:-107.50,22.51:-105.00,22.51:-102.50,22.51:-100.00,22.51:
			      -97.51,22.51:-97.51,25.00:-97.51,27.50:-97.51,30.00:-100.00,30.00
pal 50.02 30.00 3.43,-40.93 5.00,-37.49:2.50,-37.49:0.00,-37.49:0.00,-40.00:0.00,-42.50:0.00,-45.00:
			    2.50,-45.00:5.00,-45.00:5.00,-42.50:7.49,-42.50:7.49,-40.00:7.49,-37.49:5.00,-37.49
sil 37.57 25.02 115.00,-51.25 115.00,-47.50:112.49,-47.50:112.49,-50.00:112.49,-52.49:112.49,-55.00:
    	  		      115.00,-55.00:117.50,-55.00:117.50,-52.49:117.50,-50.00:117.50,-47.50:115.00,-47.50

The boundary polygons abut but do not overlap and they cover the entire sky. There is one polygon per consetllation. The total area of all constellations is `360 × 180 = 36800`.

constellation star membership

This is a list of all the stars on the chart and their constellation membership. A star is considered to be in a constellation if it falls within the constellation boundary.

The `i` and `j` indexes give the relative brightness of the star on the map and in the constellation, respectively. If a star is used to define the constellation edges it gets a + otherwise -.

DOWNLOAD

# abbreviation star i j mapp on_edge?
     aep bkawv     35     0   1.34 +
     aep   gql     65     1   1.63 +
     aep cavix     72     2   1.71 +
     aep bqxvm    137     3   2.25 +
     aep  tjow    158     4   2.31 +
     aep beelq    176     5   2.39 +
...
     yer  jjlj  39365   412   7.24 -
     yer bgswm  39464   413   7.24 -
     yer  ittu  39546   414   7.24 -
     yer  wakp  39556   415   7.24 -
     yer bedks  39667   416   7.25 -
     yer  gxzo  39817   417   7.25 -

To lookup the 10 brightest stars, sort on the i index. Here we see that megal (Megalodon) has the brightest star in the sky, jkxo with apparent magnitude `-2.05`. The next two brighest stars are in mam (Mammuthus) and ara (Araucaria).

> cat constellations.stars.txt | sort -n +2 -3 | head -10
   megal  jkxo      0     0  -2.05 +
     mam btsqy      1     0  -0.73 +
     ara ccijs      2     0  -0.38 +
     rap btaum      3     0   0.26 +
     urs bxlss      4     0   0.26 +
     tec bgrdk      5     0   0.43 +
     cop  itwr      6     0   0.45 +
     ara  mrvq      7     1   0.54 +
     phe  loju      8     0   0.54 +
     mam bhlbw      9     1   0.55 +

To get a list of the brightest star in each constellation, just search for " 0 ". Below I show this list sorted by brightness.

> cat constellations.stars.txt | grep " 0 "| sort -n +4 -5 
   megal  jkxo      0     0  -2.05 +
     mam btsqy      1     0  -0.73 +
     ara ccijs      2     0  -0.38 +
     rap btaum      3     0   0.26 +
     urs bxlss      4     0   0.26 +
     tec bgrdk      5     0   0.43 +
     cop  itwr      6     0   0.45 +
     phe  loju      8     0   0.54 +
     kel bnhwx     11     0   0.59 +
     spe  rtep     13     0   0.71 +
     ...
     nes  vxou    299     0   2.80 -
     aur bmjvf    307     0   2.81 +
     tra  puib    318     0   2.83 +
     pip  cecq    358     0   2.91 +
     pal  oife    389     0   2.97 +
     swa   gvr    463     0   3.12 +
     hui ccteo    485     0   3.17 +
     ple bzqur    506     0   3.20 +
     com  ygrn    875     0   3.64 +
     car  yjkn    933     0   3.68 +

For example, tec (Tecopa) has bgrdk as its brightest star, which is 6th brightest in the sky with an apparent magnitude of 0.43.

The constellation whose brightest star is dimmest of all first brightest stars is car (Caracara). Its brightest star is yjkn which is 934th brightest in the sky with an apparent magnitude of 3.68.

To get the number of stars in each constellation, just add the number of times the constellation abbreviation appears. Bron has the most stars of any constellation, more than twice as many as the next one, archaeo (Archaeopteryx). Both car (Caracara) and por (Porzana) have only 7 stars each, the fewest of all constellations.

   5230 bro
   2287 archaeo
   2205 thy
   2155 kim
   1838 archaea
   1789 came
   1768 ard
...
     20 megal
     19 swa
     17 mar
     12 rhy
      8 sil
      7 por
      7 car

constellation names, stories and links

The constellations are in no particular order in this file.

DOWNLOAD

# constellation name
# hemisphere (n north, s south, b both)
# common name
# Latin name
# extinction date
# URL
# optional story

aplonis
n
mysterious bird of Ulieta
Aplonis ulietensis
1774-1850
https://en.wikipedia.org/wiki/Raiatea_starling

desmodus
n
Giant Vampire Bat
Desmodus draculae
Pleistocene or early Holocene
https://www.thoughtco.com/recently-extinct-shrews-bats-and-rodents-1092147
It is thought that each night Desmodus flies up against the dome of the sky, looking for a way to escape.

...

VIEW ALL

news + thoughts

Happy 2021 `\pi` Day—
A forest of digits

Sun 14-03-2021

Celebrate `\pi` Day (March 14th) and finally see the digits through the forest.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
The 26th tree in the digit forest of `\pi`. Why is there a flower on the ground?. (details)

This year is full of botanical whimsy. A Lindenmayer system forest – deterministic but always changing. Feel free to stop and pick the flowers from the ground.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
The first 46 digits of `\pi` in 8 trees. There are so many more. (details)

And things can get crazy in the forest.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A forest of the digits of '\pi`, by ecosystem. (details)

Check out art from previous years: 2013 `\pi` Day and 2014 `\pi` Day, 2015 `\pi` Day, 2016 `\pi` Day, 2017 `\pi` Day, 2018 `\pi` Day and 2019 `\pi` Day.

Testing for rare conditions

Tue 16-03-2021

All that glitters is not gold. —W. Shakespeare

The sensitivity and specificity of a test do not necessarily correspond to its error rate. This becomes critically important when testing for a rare condition — a test with 99% sensitivity and specificity has an even chance of being wrong when the condition prevalence is 1%.

We discuss the positive predictive value (PPV) and how practices such as screen can increase it.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Testing for rare conditions. (read)

Altman, N. & Krzywinski, M. (2021) Points of significance: Testing for rare conditions. Nature Methods 18

Standardization fallacy

Tue 09-02-2021

We demand rigidly defined areas of doubt and uncertainty! —D. Adams

A popular notion about experiments is that it's good to keep variability in subjects low to limit the influence of confounding factors. This is called standardization.

Unfortunately, although standardization increases power, it can induce unrealistically low variability and lead to results that do not generalize to the population of interest. And, in fact, may be irreproducible.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Standardization fallacy. (read)

Not paying attention to these details and thinking (or hoping) that standardization is always good is the "standardization fallacy". In this column, we look at how standardization can be balanced with heterogenization to avoid this thorny issue.

Voelkl, B., Würbel, H., Krzywinski, M. & Altman, N. (2021) Points of significance: Standardization fallacy. Nature Methods 18:5–6.

Graphical Abstract Design Guidelines

Fri 13-11-2020

Clear, concise, legible and compelling.

Making a scientific graphical abstract? Refer to my practical design guidelines and redesign examples to improve organization, design and clarity of your graphical abstracts.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Graphical Abstract Design Guidelines — Clear, concise, legible and compelling.

"This data might give you a migrane"

Tue 06-10-2020

An in-depth look at my process of reacting to a bad figure — how I design a poster and tell data stories.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A poster of high BMI and obesity prevalence for 185 countries.

He said, he said — a word analysis of the 2020 Presidential Debates

Thu 01-10-2020

Building on the method I used to analyze the 2008, 2012 and 2016 U.S. Presidential and Vice Presidential debates, I explore word usagein the 2020 Debates between Donald Trump and Joe Biden.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Analysis of word usage by parts of speech for Trump and Biden reveals insight into each candidate.