
DIY Bertin Matrix with 569 Dominoes and No Glue - polm23
https://aviz.fr/diyMatrix/
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jonnydubowsky
The footnotes lead to some fascinating context into the associated research
field.

The World Values Survey, which started in 1981, is "the largest non-
commercial, cross-national, time series investigation of human beliefs and
values ever executed, currently including interviews with almost 400,000
respondents. Moreover the WVS is the only academic study covering the full
range of global variations, from very poor to very rich countries, in all of
the world’s major cultural zones".

"WVS consists of nationally representative surveys conducted in almost 100
countries which contain almost 90 percent of the world’s population, using a
common questionnaire" .

Their latest research study examines "Values In a Time Of Crisis" & the
effects of the Covid-19 pandemic on values.

"a natural experiment indeed—to study how people’s moral values behave during
times of crises. In the face of lacking evidence, we cannot take it for
granted that the glacial stability of values observed in normal times
continues throughout the Corona crisis. This uncertainty opens new territory
and raises several imminent research questions:

    
    
      - Does the Corona pandemic impact on people’s values? In other words, do people change their values under the imprint of this crisis? 
    
     - If yes, how massive are these changes? And if these changes are massive, in what direction do they move? 
    
     - How enduring are these changes, once an end of the crisis is at sight and once its economic consequences are overcome: do people’s moral values revert back to their old setpoint or does the crisis leave a lasting impact?"
    

[http://www.worldvaluessurvey.org/WVSEventsShow.jsp?ID=416](http://www.worldvaluessurvey.org/WVSEventsShow.jsp?ID=416)

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remcob
This optimization problem is very similar to that of minimizing the diagonal
bandwidth of a matrix, a common problem in large numerical computations [1].
It is also related to cluster finding in graphs and graph layouts by
considering the adjacency matrix.

The difference is that in both those cases the values are boolean, but in this
post the cost function is weighted.

[1]
[https://en.wikipedia.org/wiki/Cuthill%E2%80%93McKee_algorith...](https://en.wikipedia.org/wiki/Cuthill%E2%80%93McKee_algorithm)

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joelkevinjones
I'm a mediocre woodworker, but it seems to me cutting the dominoes on a table
saw would be faster than laser cutting. Setup a sled with a stop of the proper
width to create strips. The strips could be run through using the sled with
the stop set to a potentially different dimension. One can then use either a
drill press or a hand drill with a template to guide hole placement. A drill
press would be preferred, since getting exact placement and alignment is
essential to getting the rods to work.

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dleslie
I love the physical modelling and manipulation; but there has to be a better
way than removing and replacing all those rods every time you want to switch
dimensions, surely?

~~~
dest
If those rods were attached together like a comb, it would be much faster

~~~
adrianmonk
That could work, but it seems like part of the purpose of this form of matrix
is to be able to rearrange rows or columns as a unit. (Hence why it says,
"Reordering was clearly the most crucial.")

So for example, you might remove all the vertical rods, leave the horizontal
ones, and use the horizontal ones to rearrange rows.

This means you'd have to be able to detach the rods from the comb, but that's
probably doable. You could build the comb so that the connecting piece clamps
onto the end of the rods, for example. Put balls on the ends of the roads and
have corresponding voids in the connecting piece and a hinge to close the
connecting piece around the balls.

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isoprophlex
What a neat way of thinking about (dimension a, dimension b, value) tuples.

Does anyone know of any library to visualise data this way?

~~~
jamessb
The authors created Bertifier (project page [1], demo [2], paper [3]); the
paper has comparisons to other tools.

There was a paper at IEEE VIS last year ("Guiro: User-Guided Matrix
Reordering" [4]) about a tool that implemented > 70 matrix
seriation/reordering methods, but I don't think the code is available. There
was also a State of the Art Review on matrix re-ordering methods from 2016 [5,
6]: it is mostly about the algorithms rather than available implementations,
but it mentions reorder.js [7].

[1]: [https://aviz.fr/bertifier](https://aviz.fr/bertifier)

[2]: [https://aviz.fr/bertifier_app/](https://aviz.fr/bertifier_app/)

[3]: [https://aviz.fr/wiki/uploads/Bertifier/bertifier-
authorversi...](https://aviz.fr/wiki/uploads/Bertifier/bertifier-
authorversion.pdf)

[4]: [https://vcg.seas.harvard.edu/publications/guiro-user-
guided-...](https://vcg.seas.harvard.edu/publications/guiro-user-guided-
matrix-reordering)

[5]:
[https://onlinelibrary.wiley.com/doi/full/10.1111/cgf.12935](https://onlinelibrary.wiley.com/doi/full/10.1111/cgf.12935)

[6]:
[https://bib.dbvis.de/uploadedFiles/MatrixReorderingSTAR.pdf](https://bib.dbvis.de/uploadedFiles/MatrixReorderingSTAR.pdf)

[7]:
[https://github.com/jdfekete/reorder.js](https://github.com/jdfekete/reorder.js)

~~~
isoprophlex
O wow, what a fantastic reply. Thanks a lot for all those delicious links!

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yters
Is the reordering NP complete?

