Codechef Rating Predictor is Back

rakeshpandit · December 1, 2019, 6:36am

Is there any way to see predicted ratings ?

kid_delta0001 · December 10, 2019, 2:01pm

Will the predictor be restarted during December Long?
It was amazing.

saurabhshadow · December 10, 2019, 7:15pm

Hope it comes soon!!!

l_returns · December 11, 2019, 2:45am

I guess it might be available again after ICPC.
It’s my random guess.

akshay181998 · December 11, 2019, 11:27am

it is stopped working from a long time ago

dushsingh1995 · December 11, 2019, 12:56pm

I’m glad you guys liked it. But unfortunately there are very less chances of making it comeback. After the API was restricted, I made changes to access it using OAuth2 via credentials.

But a part of this predictor parses the submissions page of contest to get list of all participants since ranklist doesn’t have participants having zero score. Example - https://www.codechef.com/DEC19B/status/WATSCORE?page=3

Initially it was able to parse all pages. But now after 10-12 requests, the “Hold it Right there sparky” page comes because of which it can’t parse any further.

Moreover, there is an API endpoint for submissions page but you can only request 20 submissions at max per request and in 5 minute you can do max 30 requests(there is a limit from API). So in 5 minutes, you parse at max 20*30=600 submissions which is ofcourse very less considering the amount of submissions that are actually there.

arnavvarshney · December 11, 2019, 5:28pm

Does it show the sparky page after you are logged in?

kshitij_789 · December 11, 2019, 5:31pm

might be possible for div1 atleast to some extent

kshitij_789 · December 11, 2019, 5:33pm

what about parsing the submissions parallely using different logins and combining it.might work

ssjgz · December 11, 2019, 5:41pm

Do you need to fetch all submissions, or would the rankings be sufficient? Are they easier to get hold of?

Edit:

Sorry, ignore - missed an important part of your post

l_returns · December 12, 2019, 2:34am

@dushsingh1995
I don’t think we do 600 submissions in 5 mins.
600/5 = 120 per min = 2 submissions per second.
We generally have 10 submissions per min in long challenges on an average.
( Considering total submissions in a long challenge as 10^5 => 10^4 per day => 420 per hour => 7 per min )
I understand there are rejudges during long challenges. You can check for them as well parallely as api requests are 12 times than required for one iteration of all solutions.
You can check for rejudges everyday.
It’s okay if it lags in starting of long challenge or maybe during day time.
I think this works in long challenges at least. In fact this is more than enough for long challenges.
Or in worst case it works for div1.
I believe it is required only for long contests.
For short contest they’ll get ratings very soon ( by next morning).
It would be great if you can keep this predictor up for long challenges at least.
Is there anything which I am missing here ?

kshitij_789 · December 12, 2019, 3:50am

for short contests i think giving only the seed value(expected rank is enough.I)t doesn’t require so many api requests so if it is given that will be better

anon31329220 · December 12, 2019, 12:00pm

if you understand the rating formula then we can host a rating predictor which takes in two parameters current rating and rank of the contest from the user through a html form by anybackend process you can compute the next rating though this is long process but will be feasible for some time temporarily
if you can tell me or explain rating formulas I can make that brother with the help of github.io or heroku

anon31329220 · December 12, 2019, 12:01pm

anyone please explain clearly how ratings are calculated,?

arnavvarshney · December 12, 2019, 12:07pm

Noice idea. But aren’t the ratings dependent on previous rankings and everything? Some volatility factor (not sure if that’s what it’s called )

arnavvarshney · December 12, 2019, 12:14pm

github.com

vsp4/codechef-rating-predictor/blob/master/generate.js

var http = require("http");
var https = require("https");
var util = require("util");
var cheerio = require("cheerio");
var fs = require("fs");
var path = require("path");
var async = require("async");

var cacheDir = "cache";
var parseTypes = ["all", "long", "short", "ltime"]; //date_versus_rating_all"];//, "date_versus_rating_long", "date_versus_rating_short", "date_versus_rating_ltime"];

var rankData = {};
var originalData = {};
var lastRank;

var contestid;

var usercollection;
var datacollection;
var lastupdatecollection;

This file has been truncated. show original

This file may have the answer

anon31329220 · December 12, 2019, 3:25pm

thanks I will try to host it till the end of this month but which variable of your code returns the final rating and which takes input just tell me.

arnavvarshney · December 12, 2019, 4:05pm

Uhhh… that ain’t my code. Ask @vsp4 for more info, because that is from his github repo

anon31329220 · December 12, 2019, 4:28pm

@vsp4 please describe these formulas you have used so that we can make ratings predictor?

divyanshr1 · January 7, 2020, 4:20am

Can we be assured that we will get to use codechef rating predictor again ?