AaParsa's blog

Interesting Correlation between Rank and Rating Change
By AaParsa, 5 years ago, In English

Hello!

I recently learned about the Codeforces API and tried to code some to see what is going on. I found that the distribution of rating changes in every contest is almost normal (of course). Then I plotted the rating changes by their rank in some recent contests and saw these beautiful harmonies, and I think it is worth to share!

(Color of each dot shows the color of each handle before the contest.)

But there are somethings strange to me. First, why does the cyan area has a thick line in the middle? (Can you see it?) For the first time, I thought it happened because of new registrants users in Codeforces. But I saw it in 10 recent rated contests.

Second, can someone determine the goodness of a contest by these plots? Or they don't have any relations?

You can find code in this link to test and play yourself.

update: Thanks to Adhami. There were some bugs in the code. I edited the code and charts.

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5 years ago, # |
  Vote: I like it +16 Vote: I do not like it

nice :-)

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5 years ago, # |
  Vote: I like it +22 Vote: I do not like it

Maybe that thick cyan line is people creating new accounts?

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5 years ago, # |
  Vote: I like it +126 Vote: I do not like it

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5 years ago, # |
  Vote: I like it +16 Vote: I do not like it

You didn't handle that multiple users might have the same rank. I think that's the reason of the thick line.

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5 years ago, # |
  Vote: I like it +16 Vote: I do not like it

why delta of contestants who ranked below a certain threshold is almost consistent and then a leap in delta happens as we just pass that threshold?

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    5 years ago, # ^ |
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    Maybe those are the people who didn't solve anything.

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    5 years ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    Fixed:

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      5 years ago, # ^ |
        Vote: I like it +9 Vote: I do not like it

      so participants in that chunk were all ranked the same but the old code stretched them in the spectrum, the new code shows that delta wasn't consistent for a range.

      but that leap is still there, are they the ones who didn't solve anything?

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5 years ago, # |
  Vote: I like it +23 Vote: I do not like it

wow that was awesome !!!! how did you get the codeforces database??

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5 years ago, # |
  Vote: I like it +20 Vote: I do not like it

Very cool thing, thank you very much!

p.s. Help Dasha find a tourist :)

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5 years ago, # |
← Rev. 2   Vote: I like it +71 Vote: I do not like it

More interesting graph shows when you set the x value to the old rating:

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5 years ago, # |
  Vote: I like it +52 Vote: I do not like it

we can legitimately sell these graphs as modern art!

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5 years ago, # |
  Vote: I like it +27 Vote: I do not like it

Amazing !

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5 years ago, # |
  Vote: I like it +25 Vote: I do not like it

wow interesting :)

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5 years ago, # |
← Rev. 3   Vote: I like it +17 Vote: I do not like it

Agha_parsa_shakhe

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5 years ago, # |
  Vote: I like it +22 Vote: I do not like it

AAparsa orz

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5 years ago, # |
  Vote: I like it +14 Vote: I do not like it

It would be interesting after each contest to see that table and your position in it

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