diff --git a/lib/scholar/naive_bayes/bernoulli.ex b/lib/scholar/naive_bayes/bernoulli.ex index f6da0e44..da49979e 100644 --- a/lib/scholar/naive_bayes/bernoulli.ex +++ b/lib/scholar/naive_bayes/bernoulli.ex @@ -80,19 +80,29 @@ defmodule Scholar.NaiveBayes.Bernoulli do Fits a naive Bayes model. The function assumes that the targets `y` are integers between 0 and `num_classes` - 1 (inclusive). Otherwise, those samples will not contribute to `class_count`. + ## Options + #{NimbleOptions.docs(@opts_schema)} + ## Return Values + The function returns a struct with the following parameters: + * `:class_count` - Number of samples encountered for each class during fitting. This value is weighted by the sample weight when provided. + * `:class_log_priors` - Smoothed empirical log probability for each class. + * `:feature_count` - Number of samples encountered for each (class, feature) during fitting. This value is weighted by the sample weight when provided. + * `:feature_log_probability` - Empirical log probability of features given a class, ``P(x_i|y)``. + ## Examples + iex> x = Nx.iota({4, 3}) iex> y = Nx.tensor([1, 2, 0, 2]) iex> Scholar.NaiveBayes.Bernoulli.fit(x, y, num_classes: 3, binarize: 1.0) @@ -118,6 +128,7 @@ defmodule Scholar.NaiveBayes.Bernoulli do ] ) } + iex> x = Nx.iota({4, 3}) iex> y = Nx.tensor([1, 2, 0, 2]) iex> Scholar.NaiveBayes.Bernoulli.fit(x, y, num_classes: 3, force_alpha: false, alpha: 0.0) @@ -144,6 +155,7 @@ defmodule Scholar.NaiveBayes.Bernoulli do ) } """ + deftransform fit(x, y, opts \\ []) do if Nx.rank(x) != 2 do raise ArgumentError, @@ -174,11 +186,6 @@ defmodule Scholar.NaiveBayes.Bernoulli do opts = NimbleOptions.validate!(opts, @opts_schema) type = to_float_type(x) - x_binarize = - if opts[:binarize] != nil, - do: Scholar.Preprocessing.Binarizer.fit_transform(x, threshold: opts[:binarize]), - else: x - {alpha, opts} = Keyword.pop!(opts, :alpha) alpha = Nx.tensor(alpha, type: type) @@ -226,7 +233,7 @@ defmodule Scholar.NaiveBayes.Bernoulli do sample_weights_flag: sample_weights_flag ] - fit_n(x_binarize, y, class_priors, sample_weights, alpha, opts) + fit_n(x, y, class_priors, sample_weights, alpha, opts) end defnp fit_n(x, y, class_priors, sample_weights, alpha, opts) do @@ -235,6 +242,12 @@ defmodule Scholar.NaiveBayes.Bernoulli do num_classes = opts[:num_classes] + x = + case opts[:binarize] do + nil -> x + binarize ->Scholar.Preprocessing.Binarizer.fit_transform(x, threshold: binarize) + end + y_one_hot = Scholar.Preprocessing.OneHotEncoder.fit_transform(y, num_categories: num_classes) y_one_hot = Nx.select(y_one_hot, Nx.tensor(1, type: type), Nx.tensor(0, type: type)) @@ -281,7 +294,9 @@ defmodule Scholar.NaiveBayes.Bernoulli do @doc """ Perform classification on an array of test vectors `x` using `model`. You need to add sorted classes from the training data as the second argument. + ## Examples + iex> x = Nx.iota({4, 3}) iex> y = Nx.tensor([1, 2, 0, 2]) iex> model = Scholar.NaiveBayes.Bernoulli.fit(x, y, num_classes: 3) @@ -291,6 +306,7 @@ defmodule Scholar.NaiveBayes.Bernoulli do [2, 2] > """ + defn predict(%__MODULE__{} = model, x, classes) do check_dim(x, Nx.axis_size(model.feature_count, 1)) @@ -316,7 +332,9 @@ defmodule Scholar.NaiveBayes.Bernoulli do @doc """ Return log-probability estimates for the test vector `x` using `model`. + ## Examples + iex> x = Nx.iota({4, 3}) iex> y = Nx.tensor([1, 2, 0, 2]) iex> model = Scholar.NaiveBayes.Bernoulli.fit(x, y, num_classes: 3) @@ -329,6 +347,7 @@ defmodule Scholar.NaiveBayes.Bernoulli do ] > """ + defn predict_log_probability(%__MODULE__{} = model, x) do check_dim(x, Nx.axis_size(model.feature_count, 1)) jll = joint_log_likelihood(model, x) @@ -344,7 +363,9 @@ defmodule Scholar.NaiveBayes.Bernoulli do @doc """ Return probability estimates for the test vector `x` using `model`. + ## Examples + iex> x = Nx.iota({4, 3}) iex> y = Nx.tensor([1, 2, 0, 2]) iex> model = Scholar.NaiveBayes.Bernoulli.fit(x, y, num_classes: 3) @@ -357,13 +378,16 @@ defmodule Scholar.NaiveBayes.Bernoulli do ] > """ + defn predict_probability(%__MODULE__{} = model, x) do Nx.exp(predict_log_probability(model, x)) end @doc """ Return joint log probability estimates for the test vector `x` using `model`. + ## Examples + iex> x = Nx.iota({4, 3}) iex> y = Nx.tensor([1, 2, 0, 2]) iex> model = Scholar.NaiveBayes.Bernoulli.fit(x, y, num_classes: 3) @@ -376,6 +400,7 @@ defmodule Scholar.NaiveBayes.Bernoulli do ] > """ + defn predict_joint_log_probability(%__MODULE__{} = model, x) do check_dim(x, Nx.axis_size(model.feature_count, 1)) joint_log_likelihood(model, x)