nlp-scores-0.3.0: Scoring functions commonly used for evaluation in NLP and IR

NLP.Scores

Description

Scoring functions commonly used for evaluation of NLP systems. Most functions in this module work on lists, but some take a precomputed table of `Counts`. This will give a speedup if you want to compute multiple scores on the same data. For example to compute the Mutual Information, Variation of Information and the Adujusted Rand Index on the same pair of clusterings:

````>>> ````let cs = counts \$ zip "abcabc" "abaaba"
````>>> ````mapM_ (print . (\$ cs)) [mi, ari, vi]
``````

Synopsis

# Scores for classification and ranking

accuracy :: (Eq a, Fractional n) => [a] -> [a] -> nSource

Accuracy: the proportion of elements in the first list equal to elements at corresponding positions in second list. Lists should be of equal lengths.

recipRank :: (Eq a, Fractional n) => a -> [a] -> nSource

Reciprocal rank: the reciprocal of the rank at which the first arguments occurs in the list given as the second argument.

# Scores for clustering

ari :: (Ord a, Ord b) => Counts a b -> DoubleSource

mi :: (Ord a, Ord b) => Counts a b -> DoubleSource

Mutual information: MI(X,Y) = H(X) - H(X|Y) = H(Y) - H(Y|X). Also known as information gain.

vi :: (Ord a, Ord b) => Counts a b -> DoubleSource

Variation of information: VI(X,Y) = H(X) + H(Y) - 2 MI(X,Y)

# Auxiliary types and functions

type Count = DoubleSource

A count

data Counts a b Source

Count table

counts :: (Ord a, Ord b) => [(a, b)] -> Counts a bSource

Creates count table `Counts`

sum :: Num a => [a] -> aSource

The sum of a list of numbers (without overflowing stack, unlike `sum`).

mean :: (Fractional n, Real a) => [a] -> nSource

The mean of a list of numbers.

jaccard :: (Fractional n, Ord a) => Set a -> Set a -> nSource

Jaccard coefficient J(A,B) = |AB| / |A union B|

entropy :: [Count] -> DoubleSource

Entropy: H(X) = -SUM_i P(X=i) log_2(P(X=i))