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2613: Bad Map Projection: Madagascator

2022-05-02T21:02:56Z

Wasell: Undo revision 231888 by Whilе Falsе (talk)

{{comic
| number = 2613
| date = April 29, 2022
| title = Bad Map Projection: Madagascator
| image = bad_map_projection_madagascator.png
| titletext = The projection's north pole is in a small lake on the island of Mahé in the Seychelles, which is off the top of the map and larger than the rest of the Earth's land area combined.
}}

==Explanation==
This is the fifth comic in the series of [[:Category:Bad Map Projections|Bad Map Projections]] displaying Bad Map Projection #248: Madagascator. It came about 10 months after the fourth [[2489: Bad Map Projection: The Greenland Special ]] (#299).

This time, [[Randall]] used the classic {{w|Mercator projection}} but instead of placing the North Pole on top and the South Pole on the bottom it is oriented so that the top is the island of {{w|Mahé, Seychelles|Mahé}}. The map projection is technically a {{w|Oblique Mercator projection}}, with an unusual choice of the cylinder's axis. Since the Mercator projection tends to visually distort areas near the top and bottom of the resulting map, this gives some areas, notably Madagascar, very unusual shapes, hence the name the ''Madagascator''!

The Mercator projection became the standard projection for world maps during the 1800s because it is ''conformal of normal aspect'': a {{w|rhumb line}} is displayed as a straight line in a Mercator map. A rhumb line is roughly a straight line near the equator, but is very curved near the poles. During the age of sail, when navigation was performed by compass - this was a very valuable feature, since one could plot a course between two locations by measuring the direction from one to another on the map and then accounting for the difference between the magnetic and actual north poles to determine which rhumb should be taken. In the mid-20th century this trend was {{w|Mercator_projection#Criticism|criticized}} because the distortion towards the north and south poles gave an inaccurate impression of relative sizes. The most common example given of this distortion is that on a Mercator map of the world Greenland looks to have more area than Africa, when in real life Africa covers 14 times that of Greenland. Thus the reference to making Madagascar larger in this projection. Madagascar is a large island off the south east coast of the main African continent, but has only a quarter the coverage of Greenland. Greenland is often listed as the largest island in the world (which excludes continents in their own right, e.g. Australia) followed by New Guinea, Borneo and then Madagascar in fourth place.

Mahé, mentioned in the title text as the north pole's new location, is the largest island in Seychelles, with an area of 60.7 square miles. The claim in the title text that it is "larger than the rest of the Earth's land area combined", is an understatement, since the poles in the Mercator projection are infinitely far away the area occupied by Mahé in this projection is infinite. However no part of Mahé is visible on the comic.

Clicking on the actual comic will open a website that displays Mercator projections with a pole in any chosen location, with the location of the one opened set to Mahé. The chosen pole is (infinitely far to) the right of the screen, while its {{w|antipodes|antipode}} is on the left. With this, it is possible to see that the island is indeed larger than the rest of the map's land area combined, with a single national park within the island rivalling Africa in size, and at the site's cut-off point reaching a scale of distortion where a road is thicker than Panama. This also reveals that the location of the North Pole, the lake mentioned by Randall, is the Rochon Dam.

Unlike previous Bad Map Projections, Morocco and Western Sahara are drawn as one unlabelled country.

===Comparison of actual/mapped areas===
{| class="wikitable sortable"
! Landmass
! Status
! data-sort-type="number"|Actual Area<ref name="act">Major contiguous land areas that should exclude all islands, ''especially'' major ones, '''''especially''''' especially those listed separately</ref> (Millions of Km²)
! data-sort-type="number"|Proportion Land Area
! data-sort-type="number"|Proportion Image Area<ref name="pri">Of only these listed areas listed</ref>
! data-sort-type="number"|Distortion<ref name="dis">NB. Difference between percentages, rather than percentage difference</ref>
|-
| Africa<ref name="suez">Edge at Suez Canal</ref> || data-sort-value="C2"|Continent 2nd largest || 29.7 || 19.95% || 35% || +15.1%
|-
| Eurasia<ref name="suez" /> || data-sort-value="C1"|Continent Largest || 53.4 || 35.83% || 30% || -5.83%
|-
| North America<ref name="pan">Edge at Panama Canal</ref> || data-sort-value="C3"|Continent 3rd largest || 19.3 || 12.96% || 15% || +2.04%
|-
| South America<ref name="pan" /> || data-sort-value="C4"|Continent 4th largest || 17.8 || 11.96% || 7.8% || -4.16%
|-
| Antarctica<ref name="ice">Significant ice-sheets may complicate mapped/actual 'land' areas</ref> || data-sort-value="C5"|Continent 5th largest || 14.2 || 9.53% || 5.3% || -4.23%
|-
| Madagascar || data-sort-value="I04"|Island 4th largest || 0.592 || 0.40% || 2.9% || +2.50%
|-
| Australia || data-sort-value="C7"|Continent Smallest || 7.55 || 5.07% || 2.5% || -2.57%
|-
| Greenland<ref name="ice" /> || data-sort-value="I01"|Island Largest || 2.17 || 1.45% || 0.87% || -0.58%
|-
| Borneo || data-sort-value="I03"|Island 3rd largest || 0.749 || 0.50% || 0.37% || -0.13%
|-
| New Guinea || data-sort-value="I02"|Island 2nd largest || 0.786 || 0.53% || 0.32% || -0.21%
|-
| Japan<ref name="hon">Honshu only</ref> || data-sort-value="I07"|Island 7th largest || 0.228 || 0.15% || 0.10% || -0.05%
|-
| Mainland Britain || data-sort-value="I09"|Island 9th largest || 0.209 || 0.14% || 0.10% || -0.04%
|-
| Island of Ireland || data-sort-value="I20"|Island 20th largest || 0.082 || 0.05% || 0.03% || -0.02%
|}

<references/>

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
Bad map projection #248: Madagascator

Mercator projection but with the North Pole in the Indian Ocean so it exaggerates the size of Madagascar instead of Greenland. Various countries and oceans are labeled, and country borders are shown.
{{comic discussion}}

[[Category:Bad Map Projections]]

Talk:2483: Linked List Interview Problem

2021-07-01T20:00:58Z

Wasell: fix cat link

Assuming not everyone understands O notation: O(1) means that it always takes the same time, no matter how much data is stored. O(n) means the time is proportional to the amount of data stored - if you have 10 times the data, it takes 10 times as long to find the one you want. {{unsigned ip|108.162.221.84}}

This code won't mail the linked list to a museum - it will mail the memory location of the head of the list to a museum.{{unsigned ip|172.70.130.192}}
:I think part of the joke might be that the high-level language being used will actually spit out a representation of the entire list when using the str function. So it actually does all the traversing and abstracts it away, again making the interview question seem redundant! [[Special:Contributions/162.158.159.48|162.158.159.48]] 10:40, 1 July 2021 (UTC)
::The language looks almost like Python -- the only difference being the keyword ''define'' instead of ''def''. Lisp is the only family of languages I can think of that automatically converts linked lists to a representation of all the elements, since the linked list is its fundamental data structure. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 14:06, 1 July 2021 (UTC)

just to make sure I get this right.
If I want to save the numbers "1", "2", "3", "4" in an array it could (depending on the programming language) just be "[1,2,3,4]", while a linked list could be "1 (jump to 3rd entry), 4, 2 (jump to 4th entry), 3 (jump to 2nd entry)"?
Then entering 2.5 between 2 and 3 would be complicated in the array as you have to move the 3 and 4 to new places, while in the linked list you just change the direction after to to jump to 5th entry, and add 2.5 and the instruction to jump to 4th entry? While it is of course harder to find a specific entry in the linked list. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 06:01, 1 July 2021 (UTC)
:At the lowest level of access, such an array would be like the sequence "1234" (analogising to a simple string/char-array), asking for the nth-element quickly gets the nth-character by offset plus suitably multiplied memory reference). Inserting ("12a34") or deleting ("124") needs at least partial shuffling and resizing, while switching ("1324") or other internal re-ordering has widely variable overheads.
:A linked-list could be thought of as defining as "¹" with ¹="1²", ²="2³", ³="3⁴" and ⁴="4∅", taking up more initial memory, and effort to discover the nth item. But, done right and for the right reasons, additions (²="2⁵", ⁵="a³"), removals (²="2⁴", dump/reuse ³) and switches (either ²="3³", ³="2⁴" or ¹="1³", ³="3²", ²="2⁴") can be as efficient as possible once the splice-and-switch process knows which points to work with.
:(A linked-list sorter/editor will probably traverse the list, not worrying what 'offset' it is at, but holding an ⁿ pointer address for at least two adjacent items, ready to alter their ⁿs-as-reference to fulfil the change required, without worrying ''which'' ⁿs they were, and when created in whatever the next memory slot is.)
:Doubly-linked might be list header "¹" where ¹="∅1²", ²="¹2³", ³="²3⁴" and ⁴="³4∅" and is heavier in storage (though often balanced by the "1234" being much more complex as actual data (e.g. multi-word, possibly variable-length records) than the simple ⁿs, that in an array-accessed form would include far too much padding and wasting storage (or too little, requiring optionally-defined ⁿs at the end of each fixed-length record to direct to an 'overflow' memory location, effectively LLing) thus justifying the potential LL packing overheads.
:For further hybrid fun, nothing stops you having a fixed array "¹²³⁴∅∅∅" and define ¹="1", etc, then change the array-of-references accordingly ("¹²⁵³⁴∅∅", "¹²⁴∅∅∅∅", "¹³²⁴∅∅∅" or - if it's sensible - "¹²³⁴³²¹" which actually does something the LL would be hard-pressed to achieve for you without further structural overheads specifically designed for beyond-linear traversal).
:That it potentially becomes spaghetti-data should not concern you so long as you don't have spaghetti-code as well which causes some oversight of data-mangling to mess things up. And you'll probably want to maintain a custom data-dumper/collator/formatter capability to keep an eye on things as you're debugging the inevitably miswritten shuffle-function, and/or do battle with the compiler's garbage-handling insertions when you confuse it beyond reasonable limits. (No, wait, did you do full low-level garbage-handling yourself? Did you do it ''properly''? ;) )
:...but I must say I'm not overly keen to abandon modern inbuilt splice-functions (for arrays/otherwise) doing all this hard work for me. Only if I'm looking at something of more of a net-/tree-like relationship (esp. non-Euclidean), or something with complicated multi-layered disparity of pointed-at data might I design up from such basic foundations. But I can also be nostalgic about when it was far more necessary! [[Special:Contributions/162.158.159.48|162.158.159.48]] 10:18, 1 July 2021 (UTC)

Does anyone know when the last comic was that used colors? Is this something worth mentioning? --[[Special:Contributions/162.158.88.42|162.158.88.42]] 06:11, 1 July 2021 (UTC)

: I found the category: [[:Category:Comics with color]]. --[[Special:Contributions/162.158.93.153|162.158.93.153]] 06:17, 1 July 2021 (UTC)

I added some words regarding the title text. Feel free to expand/clarify/correct as necessary. [[Special:Contributions/172.69.35.209|172.69.35.209]] 06:57, 1 July 2021 (UTC)

The comic could also be a reference to the [https://en.wikipedia.org/wiki/British_Museum_Algorithm British Museum Algorithm]. --[[Special:Contributions/162.158.88.110|162.158.88.110]] 09:09, 1 July 2021 (UTC)

I second a previous comment, the code *does not* send the list to the museum, only the string representation of the head pointer. So the examiner may be rightully pissed off because both can be true: the candidate is trying to make fun of list algorithms '''and''' he doesn't know how to deal with a list.
(Unsure of what follows: given that the code looks like python, this may also be sarcasm about the style of (not only) python programming that always resorts to some external code module instead of defining new data structures and coding related methods. In this case, the external module is a museum :-) ). [[User:Xkcdmax|Xkcdmax]] ([[User talk:Xkcdmax|talk]])

Those wondering why linked lists are considered obsolete: insertion and deletion performance is rarely the issue these days. It's the cost of enumerating over all elements in the list. Both arrays and linked lists have O(n) complexity there, but arrays have the lower cost. And that's before we get into stuff like caches liking predictable access patterns (pointer chasing is not predictable) and all those pointers costing precious cache memory space.--[[User:Henke37|Henke37]] ([[User talk:Henke37|talk]]) 09:45, 1 July 2021 (UTC)

Talk:2237: AI Hiring Algorithm

2019-12-04T21:31:21Z

Wasell:

Not sure this has to do with deepmind. Deep is a term used generally for recurrent neural networks.
[[Special:Contributions/172.68.34.82|172.68.34.82]] 19:34, 4 December 2019 (UTC)

:Agree. Maybe we should just mention that? [[Special:Contributions/172.68.141.136|172.68.141.136]] 20:10, 4 December 2019 (UTC)

I don't like how "our" font for the comic title made me think it said "Al Hiring Algorithm" (although now I do want to see that comic!) (the actual xkcd website's comic title is in large/small caps, so it is unambiguous.) [[User:Mathmannix|Mathmannix]] ([[User talk:Mathmannix|talk]]) 20:17, 4 December 2019 (UTC)

I first heard about this type of system existing a few weeks ago. https://www.technologyreview.com/f/614694/hirevue-ai-automated-hiring-discrimination-ftc-epic-bias/ [[Special:Contributions/172.68.65.66|172.68.65.66]] 20:37, 4 December 2019 (UTC)

That's a big problem with AI as it's currently handled -- the AI's have to be trained, and the training is usually by feeding them lots of existing information, which means widespread errors and patterns of discrimination are inevitably going to color the AI's decisions, leading to feedback loops that favor existing discrimination. If feeding tons of books or case records or whatever to an AI, where say 95% of them were historically written by white males, one can expect an AI viewpoint that would lean towards what white men think. Garbage in, garbage out... amplified. [[User:N0lqu|-boB]] ([[User talk:N0lqu|talk]]) 21:29, 4 December 2019 (UTC)

So it's a slightly less stupid version of [https://rationalwiki.org/wiki/Roko's_basilisk Roko's basilisk]? -- [[User:Wasell|Wasell]] ([[User talk:Wasell|talk]]) 21:27, 4 December 2019 (UTC)

Talk:2237: AI Hiring Algorithm

2019-12-04T21:27:07Z

Wasell: roko?