mattpodwysocki

 'Superman Returns': 3.5, 'The Night Listener': 4.0},
'Claudia Puig': {'Snakes on a Plane': 3.5, 'Just My Luck': 3.0,
 'The Night Listener': 4.5, 'Superman Returns': 4.0, 
 'You, Me and Dupree': 2.5},
'Mick LaSalle': {'Lady in the Water': 3.0, 'Snakes on a Plane': 4.0, 
 'Just My Luck': 2.0, 'Superman Returns': 3.0, 'The Night Listener': 3.0,
 'You, Me and Dupree': 2.0}, 
'Jack Matthews': {'Lady in the Water': 3.0, 'Snakes on a Plane': 4.0,
 'The Night Listener': 3.0, 'Superman Returns': 5.0, 'You, Me and Dupree': 3.5},
'Toby': {'Snakes on a Plane':4.5,'You, Me and Dupree':1.0,'Superman Returns':4.0}}

mattpodwysocki

#light

let critics = 
  Map.of_list [("Lisa Rose", 
                Map.of_list [("Lady in the Water", 2.5);("Snakes on a Plane", 3.5);
                             ("Just My Luck", 3.0);("Superman Returns", 3.5);
                             ("You, Me and Dupree", 2.5);("The Night Listener", 3.0)];);
               ("Gene Seymour", 
                Map.of_list [("Lady in the Water", 3.0);("Snakes on a Plane", 3.5);
                             ("Just My Luck", 1.5);("Superman Returns", 5.0);

mattpodwysocki

#light

let critics = 
  Map.of_list [("Lisa Rose", 
                Map.of_list [("Lady in the Water", 2.5);("Snakes on a Plane", 3.5);
                             ("Just My Luck", 3.0);("Superman Returns", 3.5);
                             ("You, Me and Dupree", 2.5);("The Night Listener", 3.0)];);
               ("Gene Seymour", 
                Map.of_list [("Lady in the Water", 3.0);("Snakes on a Plane", 3.5);
                             ("Just My Luck", 1.5);("Superman Returns", 5.0);

mattpodwysocki

# Gets recommendations for a person by using a weighted average
# of every other user's rankings
def getRecommendations(prefs,person,similarity=sim_pearson):
  totals={}
  simSums={}
  for other in prefs:
    # don't compare me to myself
    if other==person: continue
    sim=similarity(prefs,person,other)

mattpodwysocki

#light

module Map =
  let insertWith (f:'a -> 'a -> 'a) (k:'tkey) (v:'a) (m:Map<'tkey, 'a>) =
    match Map.tryfind k m with 
    | None   -> Map.add k v m
    | Some x -> let res = f v x
                Map.add k res m

// Gets recommendations for a person by using a weighted average

mattpodwysocki

# prefs = Map String (Map String Double)

def transformPrefs(prefs):
  result={}
  for person in prefs:
    for item in prefs[person]:
      result.setdefault(item,{})
      
      # Flip item and person
      result[item][person]=prefs[person][item]

mattpodwysocki

// F#
let transformPrefs
  (prefs:Map<string, Map<string, float>>) =
  
  let add k1 k2 v m =
    let curInner = 
        match Map.tryfind k1 m with
        | None   -> Map.empty
        | Some x -> x
    m |> Map.add k1 (Map.add k2 v curInner)

mattpodwysocki

#light

module Option =
  let some  (n:'b) (f:'a -> 'b) (opt:'a option) : 'b =
    match n, f, opt with
    | n, _, None -> n
    | _, f, Some x -> f x    

module Map =
  /// Inserts into the Map with the given function if already exists, else adds

mattpodwysocki

#light

module Option =
  let some  (n:'b) (f:'a -> 'b) (opt:'a option) : 'b =
    match n, f, opt with
    | n, _, None -> n
    | _, f, Some x -> f x    

module Map =
  let insertWith (f:'a -> 'a -> 'a) (k:'tkey) (v:'a) (m:Map<'tkey, 'a>) =

mattpodwysocki

#light

module SeqMonad = 
  let bindS l f = Seq.concat (Seq.map f l)
  let returnS l = seq { yield l }
  
  type SeqBuilder() =
    member x.Delay(f) = f()
    member x.Bind(l, f) = bindS l f
    member x.Return(l) = returnS l