export function linear(...as: [number, number][]): LinearResult {

  if (!as.length) {
    return {
      b: undefined,
      m: undefined,
      fn: () => undefined,
      r2: undefined
    }
  }

  const [xs, ys] = unzip(as)
  const [sum_x, sum_y] = [xs, ys].map(sum)
  const sum_x2 = sum(xs.map(_ => _*_))
  const sum_xy = sum(as.map(([a, b]) => a * b))
  const n = as.length
  const mean_y = mean(ys)

  const m = (n * sum_xy - sum_x * sum_y) / (n * sum_x2 - sum_x * sum_x)
  const b = (sum_y - m * sum_x) / n
  const fn = (x: number) => m*x + b

  // @see https://en.wikipedia.org/wiki/Coefficient_of_determination
  const ss_res = sum(as.map(([x, y]) => square(y - fn(x))))
  const ss_tot = sum(ys.map(y => square(y - mean_y)))
  const r2 = 1 - ss_res/ss_tot

  return {b, m, fn, r2}

}

		Array.from(ratingMap.values()).filter(mappedRatings => mappedRatings.length > 1).forEach(dupeRatings => {
			// update first
			const first = dupeRatings.shift();
			queries.push(first.update({ value: Math.round(sum(dupeRatings.map((r: RatingDocument) => r.value)) / dupeRatings.length) }));
			// delete the rest
			dupeRatings.forEach((r: RatingDocument) => queries.push(r.remove()));
		});

	/**
	 * Deletes a game.
	 *
	 * @see DELETE /v1/games/:id
	 * @param {Context} ctx Koa context
	 */
	public async del(ctx: Context) {

		const game = await state.models.Game.findOne({ id: sanitize(ctx.params.id) })
			.populate({ path: '_backglass' })
			.populate({ path: '_logo' })
			.exec();

		if (!game) {
			throw new ApiError('No such game with ID "%s".', ctx.params.id).status(404);
		}

		// check for release and backglass reference and fail if there are
		const refs: { [key: string]: number } = {
			releases: await state.models.Release.countDocuments({ _game: game._id }).exec(),
			backglasses: await state.models.Backglass.countDocuments({ _game: game._id }).exec(),
		};
		if (sum(values(refs)) > 0) {
			throw new ApiError('Cannot delete game because it is referenced by %s.', Object.keys(refs).map(f => `${refs[f]} ${f}`).join(' and '))
				.status(400).warn();
		}
		await game.remove();

		logger.info(ctx.state, '[GameApi.del] Game "%s" (%s) successfully deleted.', game.title, game.id);

		await apiCache.invalidateDeletedGame(ctx.state, game);

		// log event
		await LogEventUtil.log(ctx, 'delete_game', false, { game: omit(state.serializers.Game.simple(ctx, game), ['rating', 'counter']) }, { game: game._id });

		this.success(ctx, null, 204);
	}

export default function evaluate(situation: Situation, camp: Camp): number {
  return _.sum(situation.getSlots().map( (chess, index) => {
    if (chess && chess.camp == camp) {
      return rules.of(chess).getScore(situation, index);
    } else {
      return 0;
    }
  }));
}

 this.getActiveAddresses(wallet, inGap, reportFn, function(err, addresses) {
   reportFn("Active addresses:" + JSON.stringify(addresses));
   if (err) return cb(err);
   var utxos = _.map(_.flatten(_.map(addresses, "utxo")),"amount");
   var result = {
     addresses: addresses,
     balance: _.sum(utxos),
   }
   return cb(null, result);
 });

    refresh() {
        this.playerCardsStrengths = this.ChanceCalculations.computeStrengths(this.currentDeck);
        this.strengthPercentageValues = this.playerCardsStrengths.map(strength => this.ChanceCalculations.computeStrengthPercentageValue(strength, this.Game.stack));

        let nonZeroChances = _.compact(this.strengthPercentageValues).length;
        if (nonZeroChances !== 0) {
            this.totalChance = _.sum(this.strengthPercentageValues) / nonZeroChances;
        } else {
            this.totalChance = 0;
        }
    }

 return customers.map(customer => {
     const metadata = (customer.charges[0] && customer.charges[0].metadata) || customer.subscriptions.data[0] && customer.subscriptions.data[0].metadata
     return {
         email: customer.email,
         name: metadata && metadata.name,
         showOnList: metadata && metadata.showOnList,
         isMonthly: customer.subscriptions.data.length > 0,
         created: (new Date(customer.created * 1000)).toISOString(),
         total: sum(customer.charges.map(charge => charge.amount)) / 100
     }
 })

async function runPing(url: string): Promise<number> {
  const pingUrl = async () => {
    const start = Date.now()

    await fetch(url)

    return Date.now() - start
  }
  const pings = await Promise.all([0,0].map(pingUrl))

  return sum(pings) / pings.length
}

  recalculateStats() {
    this.maxMembers = 10 + (this.buildings.levels.Academy || 0);

    const numBuildings = _.size(Buildings);
    const totalLevel = _.sum(_.values(this.buildings.levels));

    this.level = Math.max(1, Math.floor(totalLevel / numBuildings));

    this.$statBoosts = {};

    if(this.$buildingInstances.GardenSmall) {
      const smallGardenLevel = this.buildings.levels.GardenSmall;
      const smallGardenBoost1 = this.getProperty('GardenSmall', 'StatBoost1');
      this.$statBoosts[smallGardenBoost1] = smallGardenLevel;
    }

    if(this.$buildingInstances.GardenMedium) {
      const mediumGardenLevel = this.buildings.levels.GardenMedium;
      const mediumGardenBoost1 = this.getProperty('GardenMedium', 'StatBoost1');
      const mediumGardenBoost2 = this.getProperty('GardenMedium', 'StatBoost2');
      this.$statBoosts[mediumGardenBoost1] = mediumGardenLevel * 20;

      let val = 0;
      switch(mediumGardenBoost2) {
        case 'gold':                    val = 10; break;
        case 'xp':                      val = 2; break;
        case 'itemFindRangeMultiplier': val = 0.05; break;
        case 'salvage':                 val = 1; break;
      }
      this.$statBoosts[mediumGardenBoost2] = mediumGardenLevel * val;
    }

    if(this.$buildingInstances.GardenLarge) {
      const largeGardenLevel = this.buildings.levels.GardenLarge;
      const largeGardenBoost1 = this.getProperty('GardenLarge', 'StatBoost1');
      const largeGardenBoost2 = this.getProperty('GardenLarge', 'StatBoost2');
      const largeGardenBoost3 = this.getProperty('GardenLarge', 'StatBoost3');

      this.$statBoosts[largeGardenBoost1] = largeGardenLevel;
      this.$statBoosts[largeGardenBoost2] = largeGardenLevel;

      let val = 0;
      switch(largeGardenBoost3) {
        case 'hp': case 'mp':           val = 1000; break;
        case 'hpregen': case 'mpregen': val = 200; break;
        case 'damageReduction':         val = 100; break;
      }

      this.$statBoosts[largeGardenBoost3] = largeGardenLevel * val;
    }
  }

 return function (engine, locale) {
     function pick(n: number, [[k, x], ...xs]): any {
         return (n <= k) ? x : pick(n - k, xs);
     }
     const total = sum(pool.map(e => e[0]));
     const head = integer(1, total)(engine);
     const result = pick(head, pool);
     if (result instanceof Arbitrary) {
         return result.makeGenerator()(engine, locale);
     }
     else {
         return result;
     };
 };