compute elasticity

common/calculate-metrics.ts

@@ -1,9 +1,15 @@
 import { last, sortBy, sum, sumBy } from 'lodash'
 import { calculatePayout } from './calculate'
-import { Bet } from './bet'
+import { Bet, LimitBet } from './bet'
-import { Contract } from './contract'
+import {
+  Contract,
+  CPMMContract,
+  DPMContract,
+} from './contract'
 import { PortfolioMetrics, User } from './user'
 import { DAY_MS } from './util/time'
+import { getBinaryCpmmBetInfo, getNewMultiBetInfo } from './new-bet'
+import { getCpmmProbability } from './calculate-cpmm'
 
 const computeInvestmentValue = (
   bets: Bet[],
@@ -40,6 +46,55 @@ export const computeInvestmentValueCustomProb = (
   })
 }
 
+export const computeElasticity = (
+  bets: Bet[],
+  contract: Contract,
+  betAmount = 50
+) => {
+  const { mechanism, outcomeType } = contract
+  return mechanism === 'cpmm-1' &&
+    (outcomeType === 'BINARY' || outcomeType === 'PSEUDO_NUMERIC')
+    ? computeBinaryCpmmElasticity(bets, contract, betAmount)
+    : computeDpmElasticity(contract, betAmount)
+}
+
+export const computeBinaryCpmmElasticity = (
+  bets: Bet[],
+  contract: CPMMContract,
+  betAmount = 50
+) => {
+  const limitBets = bets
+    .filter(
+      (b) =>
+        !b.isFilled && !b.isSold && !b.isRedemption && !b.sale && !b.isCancelled
+    )
+    .sort((a, b) => a.createdTime - b.createdTime)
+
+  const { newPool: poolY, newP: pY } = getBinaryCpmmBetInfo(
+    'YES',
+    betAmount,
+    contract,
+    undefined,
+    limitBets as LimitBet[]
+  )
+  const resultYes = getCpmmProbability(poolY, pY)
+
+  const { newPool: poolN, newP: pN } = getBinaryCpmmBetInfo(
+    'NO',
+    betAmount,
+    contract,
+    undefined,
+    limitBets as LimitBet[]
+  )
+  const resultNo = getCpmmProbability(poolN, pN)
+
+  return resultYes - resultNo
+}
+
+export const computeDpmElasticity = (contract: DPMContract, betAmount = 50) => {
+  return getNewMultiBetInfo('', betAmount, contract).newBet.probAfter
+}
+
 const computeTotalPool = (userContracts: Contract[], startTime = 0) => {
   const periodFilteredContracts = userContracts.filter(
     (contract) => contract.createdTime >= startTime

common/contract.ts

@@ -49,6 +49,7 @@ export type Contract<T extends AnyContractType = AnyContractType> = {
   volume: number
   volume24Hours: number
   volume7Days: number
+  elasticity: number
 
   collectedFees: Fees
 

common/new-bet.ts

@@ -17,8 +17,7 @@ import {
 import {
   CPMMBinaryContract,
   DPMBinaryContract,
-  FreeResponseContract,
+  DPMContract,
-  MultipleChoiceContract,
   NumericContract,
   PseudoNumericContract,
 } from './contract'
@@ -325,7 +324,7 @@ export const getNewBinaryDpmBetInfo = (
 export const getNewMultiBetInfo = (
   outcome: string,
   amount: number,
-  contract: FreeResponseContract | MultipleChoiceContract
+  contract: DPMContract
 ) => {
   const { pool, totalShares, totalBets } = contract
 

common/new-contract.ts

@@ -70,6 +70,7 @@ export function getNewContract(
     volume: 0,
     volume24Hours: 0,
     volume7Days: 0,
+    elasticity: propsByOutcomeType.mechanism === 'cpmm-1' ? 0.38 : 0.56,
 
     collectedFees: {
       creatorFee: 0,

functions/src/update-metrics.ts

@@ -14,6 +14,7 @@ import {
   calculateNewPortfolioMetrics,
   calculateNewProfit,
   calculateProbChanges,
+  computeElasticity,
   computeVolume,
 } from '../../common/calculate-metrics'
 import { getProbability } from '../../common/calculate'
@@ -103,6 +104,7 @@ export async function updateMetricsCore() {
         fields: {
           volume24Hours: computeVolume(contractBets, now - DAY_MS),
           volume7Days: computeVolume(contractBets, now - DAY_MS * 7),
+          elasticity: computeElasticity(contractBets, contract),
           ...cpmmFields,
         },
       }