# Model Persistence MultiLayerNetwork and ComputationGraph both have save and load methods. You can save/load a MultiLayerNetwork using: ```java MultiLayerNetwork net = ... net.save(new File("..."); MultiLayerNetwork net2 = MultiLayerNetwork.load(new File("..."), true); ``` Similarly, you can save/load a ComputationGraph using: ```java ComputationGraph net = ... net.save(new File("...")); ComputationGraph net2 = ComputationGraph.load(new File("..."), true); ``` Internally, these methods use the `ModelSerializer` class, which handles loading and saving models. There are two methods for saving models shown in the examples through the link. The first example saves a normal multilayer network, the second one saves a [computation graph](https://deeplearning4j.org/docs/latest/deeplearning4j-nn-computationgraph). Here is a [basic example](https://github.com/eclipse/deeplearning4j-examples/tree/master/dl4j-examples/src/main/java/org/deeplearning4j/examples/misc/modelsaving) with code to save a computation graph using the `ModelSerializer` class, as well as an example of using ModelSerializer to save a neural net built using MultiLayer configuration. ## RNG Seed If your model uses probabilities (i.e. DropOut/DropConnect), it may make sense to save it separately, and apply it after model is restored; i.e: ```java Nd4j.getRandom().setSeed(12345); ModelSerializer.restoreMultiLayerNetwork(modelFile); ``` This will guarantee equal results between sessions/JVMs. ## ModelSerializer [\[source\]](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-nn/src/main/java/org/deeplearning4j/util/ModelSerializer.java) Utility class suited to save/restore neural net models **writeModel** ``` public static void writeModel(@NonNull Model model, @NonNull File file, boolean saveUpdater) throws IOException ``` Write a model to a file * param model the model to write * param file the file to write to * param saveUpdater whether to save the updater or not * throws IOException **writeModel** ``` public static void writeModel(@NonNull Model model, @NonNull File file, boolean saveUpdater,DataNormalization dataNormalization) throws IOException ``` Write a model to a file * param model the model to write * param file the file to write to * param saveUpdater whether to save the updater or not * param dataNormalization the normalizer to save (optional) * throws IOException **writeModel** ``` public static void writeModel(@NonNull Model model, @NonNull String path, boolean saveUpdater) throws IOException ``` Write a model to a file path * param model the model to write * param path the path to write to * param saveUpdater whether to save the updater or not * throws IOException **writeModel** ``` public static void writeModel(@NonNull Model model, @NonNull OutputStream stream, boolean saveUpdater) throws IOException ``` Write a model to an output stream * param model the model to save * param stream the output stream to write to * param saveUpdater whether to save the updater for the model or not * throws IOException **writeModel** ``` public static void writeModel(@NonNull Model model, @NonNull OutputStream stream, boolean saveUpdater,DataNormalization dataNormalization) throws IOException ``` Write a model to an output stream * param model the model to save * param stream the output stream to write to * param saveUpdater whether to save the updater for the model or not * param dataNormalization the normalizer ot save (may be null) * throws IOException **restoreMultiLayerNetwork** ``` public static MultiLayerNetwork restoreMultiLayerNetwork(@NonNull File file) throws IOException ``` Load a multi layer network from a file * param file the file to load from * return the loaded multi layer network * throws IOException **restoreMultiLayerNetwork** ``` public static MultiLayerNetwork restoreMultiLayerNetwork(@NonNull File file, boolean loadUpdater) throws IOException ``` Load a multi layer network from a file * param file the file to load from * return the loaded multi layer network * throws IOException **restoreMultiLayerNetwork** ``` public static MultiLayerNetwork restoreMultiLayerNetwork(@NonNull InputStream is, boolean loadUpdater) throws IOException ``` Load a MultiLayerNetwork from InputStream from an input stream\ Note: the input stream is read fully and closed by this method. Consequently, the input stream cannot be re-used. * param is the inputstream to load from * return the loaded multi layer network * throws IOException * see #restoreMultiLayerNetworkAndNormalizer(InputStream, boolean) **restoreMultiLayerNetwork** ``` public static MultiLayerNetwork restoreMultiLayerNetwork(@NonNull InputStream is) throws IOException ``` Restore a multi layer network from an input stream\ Note: the input stream is read fully and closed by this method. Consequently, the input stream cannot be re-used. * param is the input stream to restore from * return the loaded multi layer network * throws IOException * see #restoreMultiLayerNetworkAndNormalizer(InputStream, boolean) **restoreMultiLayerNetwork** ``` public static MultiLayerNetwork restoreMultiLayerNetwork(@NonNull String path) throws IOException ``` Load a MultilayerNetwork model from a file * param path path to the model file, to get the computation graph from * return the loaded computation graph * throws IOException **restoreMultiLayerNetwork** ``` public static MultiLayerNetwork restoreMultiLayerNetwork(@NonNull String path, boolean loadUpdater) throws IOException ``` Load a MultilayerNetwork model from a file * param path path to the model file, to get the computation graph from * return the loaded computation graph * throws IOException **restoreComputationGraph** ``` public static ComputationGraph restoreComputationGraph(@NonNull String path) throws IOException ``` Restore a MultiLayerNetwork and Normalizer (if present - null if not) from the InputStream. Note: the input stream is read fully and closed by this method. Consequently, the input stream cannot be re-used. * param is Input stream to read from * param loadUpdater Whether to load the updater from the model or not * return Model and normalizer, if present * throws IOException If an error occurs when reading from the stream **restoreComputationGraph** ``` public static ComputationGraph restoreComputationGraph(@NonNull String path, boolean loadUpdater) throws IOException ``` Load a computation graph from a file * param path path to the model file, to get the computation graph from * return the loaded computation graph * throws IOException **restoreComputationGraph** ``` public static ComputationGraph restoreComputationGraph(@NonNull InputStream is, boolean loadUpdater) throws IOException ``` Load a computation graph from a InputStream * param is the inputstream to get the computation graph from * return the loaded computation graph * throws IOException **restoreComputationGraph** ``` public static ComputationGraph restoreComputationGraph(@NonNull InputStream is) throws IOException ``` Load a computation graph from a InputStream * param is the inputstream to get the computation graph from * return the loaded computation graph * throws IOException **restoreComputationGraph** ``` public static ComputationGraph restoreComputationGraph(@NonNull File file) throws IOException ``` Load a computation graph from a file * param file the file to get the computation graph from * return the loaded computation graph * throws IOException **restoreComputationGraph** ``` public static ComputationGraph restoreComputationGraph(@NonNull File file, boolean loadUpdater) throws IOException ``` Restore a ComputationGraph and Normalizer (if present - null if not) from the InputStream. Note: the input stream is read fully and closed by this method. Consequently, the input stream cannot be re-used. * param is Input stream to read from * param loadUpdater Whether to load the updater from the model or not * return Model and normalizer, if present * throws IOException If an error occurs when reading from the stream **taskByModel** ``` public static Task taskByModel(Model model) ``` * param model * return **addNormalizerToModel** ``` public static void addNormalizerToModel(File f, Normalizer normalizer) ``` This method appends normalizer to a given persisted model. PLEASE NOTE: File should be model file saved earlier with ModelSerializer * param f * param normalizer **addObjectToFile** ``` public static void addObjectToFile(@NonNull File f, @NonNull String key, @NonNull Object o) ``` Add an object to the (already existing) model file using Java Object Serialization. Objects can be restored using {- link #getObjectFromFile(File, String)} * param f File to add the object to * param key Key to store the object under * param o Object to store using Java object serialization