95 lines
3.2 KiB
Go
95 lines
3.2 KiB
Go
package recommendation
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import (
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"math"
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"testing"
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)
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func approxEq(a, b float64) bool { return math.Abs(a-b) < 1e-9 }
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func TestSimilarity_IdenticalVectors_Returns1(t *testing.T) {
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v := SessionVector{
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Artists: []string{"a1", "a2"},
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Tags: map[string]int{"rock": 2, "indie": 1},
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}
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got := Similarity(v, v, DefaultSimilarityWeights)
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if !approxEq(got, 1.0) {
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t.Errorf("Similarity(v,v) = %v, want 1.0", got)
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}
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}
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func TestSimilarity_FullyDisjoint_Returns0(t *testing.T) {
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a := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 1}}
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b := SessionVector{Artists: []string{"a2"}, Tags: map[string]int{"jazz": 1}}
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got := Similarity(a, b, DefaultSimilarityWeights)
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if !approxEq(got, 0.0) {
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t.Errorf("disjoint = %v, want 0.0", got)
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}
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}
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func TestSimilarity_TagsOnlyShared_AppliesTagsWeight(t *testing.T) {
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a := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 1}}
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b := SessionVector{Artists: []string{"a2"}, Tags: map[string]int{"rock": 5}}
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got := Similarity(a, b, DefaultSimilarityWeights)
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if !approxEq(got, 0.7) {
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t.Errorf("tags-only = %v, want 0.7", got)
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}
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}
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func TestSimilarity_ArtistsOnlyShared_AppliesArtistsWeight(t *testing.T) {
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a := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 1}}
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b := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"jazz": 1}}
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got := Similarity(a, b, DefaultSimilarityWeights)
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if !approxEq(got, 0.3) {
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t.Errorf("artists-only = %v, want 0.3", got)
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}
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}
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func TestSimilarity_EitherSeed_Returns0(t *testing.T) {
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v := SessionVector{Artists: []string{"a"}, Tags: map[string]int{"rock": 1}}
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seed := SessionVector{Seed: true, Artists: []string{"a"}, Tags: map[string]int{"rock": 1}}
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if got := Similarity(v, seed, DefaultSimilarityWeights); !approxEq(got, 0.0) {
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t.Errorf("v vs seed = %v, want 0.0", got)
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}
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if got := Similarity(seed, v, DefaultSimilarityWeights); !approxEq(got, 0.0) {
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t.Errorf("seed vs v = %v, want 0.0", got)
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}
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}
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func TestSimilarity_BothEmpty_Returns0NotNaN(t *testing.T) {
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a := SessionVector{}
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b := SessionVector{}
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got := Similarity(a, b, DefaultSimilarityWeights)
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if math.IsNaN(got) || !approxEq(got, 0.0) {
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t.Errorf("empty = %v, want 0.0 (not NaN)", got)
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}
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}
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func TestSimilarity_OneAxisEmptyOneSide_AxisContributesZero(t *testing.T) {
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a := SessionVector{Tags: map[string]int{"rock": 1}}
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b := SessionVector{Artists: []string{"a1"}}
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got := Similarity(a, b, DefaultSimilarityWeights)
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if !approxEq(got, 0.0) {
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t.Errorf("one-axis-each = %v, want 0.0", got)
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}
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}
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func TestSimilarity_PartialTagsOverlap(t *testing.T) {
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a := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 1, "indie": 1}}
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b := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 1, "jazz": 1}}
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got := Similarity(a, b, DefaultSimilarityWeights)
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want := 0.7*(1.0/3.0) + 0.3*1.0
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if !approxEq(got, want) {
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t.Errorf("partial = %v, want %v", got, want)
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}
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}
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func TestSimilarity_BagOfCountsCollapsesToSet(t *testing.T) {
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a := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 2, "indie": 1}}
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b := SessionVector{Artists: []string{"a1"}, Tags: map[string]int{"rock": 5, "indie": 3}}
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got := Similarity(a, b, DefaultSimilarityWeights)
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if !approxEq(got, 1.0) {
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t.Errorf("set-collapse = %v, want 1.0", got)
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}
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}
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