Choose a random sample of 10 values from an unbounded stream. Red marks denote values currently in the sample.
From Wikipedia:
The algorithm creates a "reservoir" array of size k and populates it with the first k items of S. It then iterates through the remaining elements of S until S is exhausted. At the ith element of S, the algorithm generates a random number j between 1 and i. If j is less than k, the jth element of the reservoir array is replaced
| {-# OPTIONS_GHC -Wall #-} | |
| {-# LANGUAGE DataKinds, GADTs, TypeOperators #-} | |
| {-# LANGUAGE FlexibleContexts, FlexibleInstances, ScopedTypeVariables #-} | |
| {-# LANGUAGE MultiParamTypeClasses, TypeFamilies #-} | |
| module Main where | |
| main :: IO () | |
| main = do | |
| print aList | |
| print elt0 |
| {-# LANGUAGE AllowAmbiguousTypes #-} | |
| {-# LANGUAGE ConstraintKinds #-} | |
| {-# LANGUAGE DataKinds #-} | |
| {-# LANGUAGE DeriveDataTypeable #-} | |
| {-# LANGUAGE FlexibleContexts #-} | |
| {-# LANGUAGE FlexibleInstances #-} | |
| {-# LANGUAGE MultiParamTypeClasses #-} | |
| {-# LANGUAGE RankNTypes #-} | |
| {-# LANGUAGE ScopedTypeVariables #-} | |
| {-# LANGUAGE TypeFamilies #-} |
| {-# LANGUAGE OverloadedStrings #-} | |
| module Deep where | |
| import Control.Monad | |
| import Data.Aeson | |
| import Data.Aeson.Types | |
| import Data.ByteString.Lazy | |
| import Data.Text | |
$ npm install
$ npm start
| """ | |
| Arguments are the parameters of a deterministic finite automaton: | |
| q -- states (list of strings) | |
| si -- input alphabet (list of characters) | |
| de -- transition function ((index of q),(index of si) --> (index of q)) | |
| s -- start state (index of q) | |
| f -- accept states (list of (index of q)) | |
| Returns a generator function which takes a string and generates successive | |
| states (indices of q) as the DFA runs on the string. | |
| """ |
| [ | |
| { | |
| "tags": [ | |
| "Others", | |
| "Tech startups", | |
| "Homes", | |
| "Offices", | |
| "Corporate office", | |
| "Work", | |
| "Services", |
| [ | |
| { | |
| "tags": [ | |
| "Japanese restaurants", | |
| "Restaurant", | |
| "Sushi", | |
| "Bar", | |
| "Food", | |
| "Food & drink", | |
| "Japanese restaurant" |
| [ | |
| { | |
| "type": "event", | |
| "status": "active", | |
| "image_url": null, | |
| "expiration_date": "2011-10-01T13:00:00-07:00", | |
| "place": { | |
| "name": "Nelson Blue", | |
| "lon": -74.001573, | |
| "city": "New York", |
| { | |
| "type": "event", | |
| "status": "active", | |
| "image_url": "http://s3.amazonaws.com/prestigedevelopment/beta/offer_photos/4e5f502fceb01f000100139f.jpg?1314869295", | |
| "place": { | |
| "name": "Chelsea Piers - Pier 62", | |
| "lon": -74.005973, | |
| "city": "New York", | |
| "address": ", ", | |
| "postal_code": "", |