Add load_lastfm data loader to get the user-artist listening frequency data

README.md

@@ -32,8 +32,14 @@ Change the code and test locally:
 ```
 $ julia
 julia> using Pkg; Pkg.activate(@__DIR__); Pkg.instantiate()
-# hit `]`
-(Recommendation) pkg> test
+julia> Pkg.test("Recommendation")
+julia> Pkg.test("Recommendation", test_args=["download"])
+```
+
+Note that unit tests for dataset loaders (e.g., `load_movielens_lates()`) are conditionally triggered as follows, so that CI does not make excessive download requests to the external sites:
+
+```
+julia> Pkg.test("Recommendation", test_args=["download"])
 ```
 
 Build documentation contents:

src/datasets.jl

@@ -1,4 +1,4 @@
-export get_data_home, download_file, unzip, load_movielens_100k, load_movielens_latest, load_amazon_review
+export get_data_home, download_file, unzip, load_movielens_100k, load_movielens_latest, load_amazon_review, load_lastfm
 
 """
     get_data_home([data_home=nothing]) -> String
@@ -48,6 +48,7 @@ function unzip(path::String, exdir::Union{String, Nothing}=nothing)
     if exdir == nothing
         exdir = dirname(path)
     end
+    get_data_home(exdir)
     zip_reader = ZipFile.Reader(path)
     for file in zip_reader.files
         out_path = joinpath(exdir, file.name)
@@ -125,18 +126,14 @@ end
 
 
 """
-    load_movielens_latest([path=nothing])
+    load_movielens_latest([path=nothing]) -> DataAccessor
 
 `path` points to a locally saved [MovieLens Latest (Small)](https://files.grouplens.org/datasets/movielens/ml-latest-small-README.html).
 Read user-item-rating triples in the folder, and convert them into a `DataAccessor` instance.
 
 Download and decompress a corresponding zip file, if `path` is not given or the specified folder does not exist.
 """
 function load_movielens_latest(path::Union{String, Nothing}=nothing)
-    n_user = 610
-    n_item = 9742
-    R = matrix(n_user, n_item)
-
     if path == nothing || !isdir(path)
         zip_path = path
         if zip_path != nothing
@@ -282,3 +279,49 @@ function load_amazon_review(path::Union{String, Nothing}=nothing; category::Stri
     end
     DataAccessor(events, n_user, n_item)
 end
+
+"""
+    load_lastfm([path=nothing]) -> DataAccessor
+
+`path` points to a locally saved [HetRec 2011 Last.FM dataset](https://files.grouplens.org/datasets/hetrec2011/hetrec2011-lastfm-readme.txt)
+Each row has a tuple of (user, artist, # of listenings).
+"""
+function load_lastfm(path::Union{String, Nothing}=nothing)
+    if path == nothing || !isdir(path)
+        zip_path = path
+        if zip_path != nothing
+            zip_path = joinpath(dirname(zip_path), "hetrec2011-lastfm-2k.zip")
+        end
+        zip_path = download_file("https://files.grouplens.org/datasets/hetrec2011/hetrec2011-lastfm-2k.zip", zip_path)
+        path = unzip(zip_path, path)
+    end
+
+    events = Array{Event, 1}()
+    n_user, n_item = 0, 0
+    user_ids, item_ids = Dict{Integer, Integer}(), Dict{Integer, Integer}()
+    open(joinpath(path, "user_artists.dat"), "r") do io
+        for (index, line) in enumerate(eachline(io))
+            if index == 1
+                continue
+            end
+            l = split(line, "\t")
+            user, item, cnt = parse(Int, l[1]), parse(Int, l[2]), parse(Int, l[3])
+            if haskey(user_ids, user)
+                u = user_ids[user]
+            else
+                n_user += 1
+                u = n_user
+                user_ids[user] = n_user
+            end
+            if haskey(item_ids, item)
+                i = item_ids[item]
+            else
+                n_item += 1
+                i = n_item
+                item_ids[item] = n_item
+            end
+            push!(events, Event(u, i, cnt))
+        end
+    end
+    DataAccessor(events, n_user, n_item)
+end

test/test_datasets.jl

@@ -91,9 +91,21 @@ function test_load_amazon_review()
     @test data.R[1, 1] == 5.0
 end
 
+function test_load_lastfm()
+    path = tempname()
+    println("-- Testing download and read Last.FM user-artist listening frequency dataset at: $path")
+
+    data = load_lastfm(path)
+    @test data.R[1, 1] == 13883
+end
+
 test_get_data_home()
-test_download_file()
 test_unzip()
-test_load_movielens_100k()
-test_load_movielens_latest()
-test_load_amazon_review()
+
+if "download" in ARGS
+    test_download_file()
+    test_load_movielens_100k()
+    test_load_movielens_latest()
+    test_load_amazon_review()
+    test_load_lastfm()
+end