GMF.py

# Generalized Matrix Factorization
def GMF(num_users, num_items, k, reg):
    """Models the interaction between user/item LV w/ linear dot-product"""
    print("using dot-product interaction term")

    seed = 1
    uid = Input((1,), name="uid")
    iid = Input((1,), name="iid")

    item_bias = Embedding(
        num_items,
        1,
        input_length=1,
        name="item_bias",
        embeddings_regularizer=regularizers.l2(reg),
        embeddings_initializer=initializers.glorot_normal(seed=seed),
    )

    user_emb = Embedding(
        num_users,
        k,
        input_length=1,
        name="user_embedding",
        embeddings_regularizer=regularizers.l2(reg),
        embeddings_initializer=initializers.glorot_normal(seed=seed),
    )
    item_emb = Embedding(
        num_items,
        k,
        input_length=1,
        name="item_embedding",
        embeddings_regularizer=regularizers.l2(reg),
        embeddings_initializer=initializers.glorot_normal(seed=seed),
    )

    u = Flatten(name="u")(user_emb(uid))
    i = Flatten(name="i")(item_emb(iid))
    i_b = Flatten(name="i_b")(item_bias(iid))

    xui = Add(name="xui")([i_b, Dot(1)([u, i])])

    model = Model(inputs=[uid, iid], outputs=xui, name="xui")
    return model