Results of 2013-08-22 F# Dojo http://www.meetup.com/Detroit-F-Meetup/events/132420742/

gistfile1.fs

// see problem description and sample training CSVs here: https://gist.github.com/mathias-brandewinder/5558573

open System
open System.IO

let trainingPath = @"data\trainingsample.csv"
let validationPath = @"data\validationsample.csv"

type Example = { Label:int; Pixels:int[] }

// split by comma
// parse strings to ints
// create Example type, 0th index is label, everything else is Pixels
let parseToExample input = 
    let parsed = input |> Array.map int 
    { Label = parsed.[0]; Pixels = parsed.[1..]}

let csvSplit (input:string) = input.Split(',')
let fileToExamples path = 
    File.ReadAllLines(path).[1..]
    |> Array.map csvSplit
    |> Array.map parseToExample

// create distance function
// distance = square root of sums of squares of difference
let distance (unknown:int[]) (e1:Example) = 
    Array.map2 (fun p1 p2 -> (float (p1 - p2))**2.0) e1.Pixels unknown
    |> Array.sum
    |> Math.Sqrt

let trainingDB = fileToExamples trainingPath
let validationDB = fileToExamples validationPath

// get record with minimum score
let classify (unknown:int[]) =
    let winner = trainingDB |> Array.minBy (distance unknown)
    winner.Label

let total = validationDB.Length
let classified = validationDB |> Seq.where (fun (r) -> r.Label = classify(r.Pixels)) |> Seq.length