如何在 Java 中为 TensorFlow DNNRegressor 提供输入？

我设法使用 DNNRegressor 编写了 TensorFlow python 程序。我已经训练了模型，并且能够通过手动创建的输入（常量张量）从 Python 中的模型中获得预测。我还能够以二进制格式导出模型。

import pandas as pd
import numpy as np
import tensorflow as tf
from tensorflow.python.framework import graph_util

#######################
# Setup
#######################

# Converting Data into Tensors
def input_fn(df, training = True):
    # Creates a dictionary mapping from each continuous feature column name (k) to
    # the values of that column stored in a constant Tensor.
    continuous_cols = {k: tf.constant(df[k].values)
                    for k in continuous_features}

    feature_cols = dict(list(continuous_cols.items()))

    if training:
        # Converts the label column into a constant Tensor.
        label = tf.constant(df[LABEL_COLUMN].values)

        # Returns the feature columns and the label.
        return feature_cols, label

    # Returns the feature columns    
    return feature_cols

def train_input_fn():
    return input_fn(train_df)

def eval_input_fn():
    return input_fn(evaluate_df)

#######################
# Data Preparation
#######################
df_train_ori = pd.read_csv('training.csv')
df_test_ori = pd.read_csv('test.csv')
train_df = df_train_ori.head(10000)
evaluate_df = df_train_ori.tail(5)
test_df = df_test_ori.head(1)
MODEL_DIR = "/tmp/model"
BIN_MODEL_DIR = "/tmp/modelBinary"
features = train_df.columns
continuous_features = [feature for feature in features if 'label' not in feature]
LABEL_COLUMN = 'label'

engineered_features = []

for continuous_feature in continuous_features:
    engineered_features.append(
        tf.contrib.layers.real_valued_column(
            column_name=continuous_feature,
            dimension=1,
            default_value=None,
            dtype=tf.int64,
            normalizer=None
            ))


#######################
# Define Our Model
#######################
regressor = tf.contrib.learn.DNNRegressor(
    feature_columns=engineered_features,
    label_dimension=1,
    hidden_units=[128, 256, 512], 
    model_dir=MODEL_DIR
    )

#######################
# Training Our Model
#######################
wrap = regressor.fit(input_fn=train_input_fn, steps=5)

#######################
# Evaluating Our Model
#######################
results = regressor.evaluate(input_fn=eval_input_fn, steps=1)
for key in sorted(results):
    print("%s: %s" % (key, results[key]))

#######################
# Save binary model (to be used in Java)
#######################
tfrecord_serving_input_fn = tf.contrib.learn.build_parsing_serving_input_fn(tf.contrib.layers.create_feature_spec_for_parsing(engineered_features)) 
regressor.export_savedmodel(
    export_dir_base=BIN_MODEL_DIR, 
    serving_input_fn = tfrecord_serving_input_fn,
    assets_extra=None,
    as_text=False,
    checkpoint_path=None,
    strip_default_attrs=False)

我的下一步是将模型加载到 java 中并做出一些预测。然而，我在用 Java 指定模型的输入时遇到了问题。

import org.tensorflow.*;
import org.tensorflow.framework.MetaGraphDef;
import org.tensorflow.framework.SignatureDef;
import org.tensorflow.framework.TensorInfo;
import java.util.List;
import java.util.Map;

public class ModelEvaluator {
    public static void main(String[] args) throws Exception {
        System.out.println("Using TF version: " + TensorFlow.version());

        SavedModelBundle model = SavedModelBundle.load("/tmp/modelBinary/1546510038", "serve");
        Session session = model.session();

        printSignature(model);
        printAllNodes(model);

        float[][] km1 = new float[1][1];
        km1[0][0] = 10;
        Tensor inKm1 = Tensor.create(km1);

        float[][] km2 = new float[1][1];
        km2[0][0] = 10000;
        Tensor inKm2 = Tensor.create(km2);

        List<Tensor<?>> outputs = session.runner()
                .feed("dnn/input_from_feature_columns/input_from_feature_columns/km1/ToFloat", inKm1)
                .feed("dnn/input_from_feature_columns/input_from_feature_columns/km2/ToFloat", inKm2)
                .fetch("dnn/regression_head/predictions/Identity:0")
                .run();

        System.out.println("\n\nOutputs from evaluation:");
        for (Tensor<?> output : outputs) {
            if (output.dataType() == DataType.STRING) {
                System.out.println(new String(output.bytesValue()));
            } else {
                float[] outArray = new float[1];
                output.copyTo(outArray);
                System.out.println(outArray[0]);
            }
        }
    }

    public static void printAllNodes(SavedModelBundle model) {
        model.graph().operations().forEachRemaining(x -> {
            System.out.println(x.name() + "   " + x.numOutputs());
        });
    }


    /**
     * This info can also be obtained from a command prompt via the command:
     * saved_model_cli show  --dir <dir-to-the-model> --tag_set serve --signature_def serving_default
     * <p>
     * See this where they also try to input data to a DNN regressor:
     * https://github.com/tensorflow/tensorflow/issues/12367
     * <p>
     * https://github.com/tensorflow/tensorflow/issues/14683
     * <p>
     * https://github.com/migueldeicaza/TensorFlowSharp/issues/293
     */
    public static void printSignature(SavedModelBundle model) throws Exception {
        MetaGraphDef m = MetaGraphDef.parseFrom(model.metaGraphDef());
        SignatureDef sig = m.getSignatureDefOrThrow("serving_default");
        int numInputs = sig.getInputsCount();
        int i = 1;
        System.out.println("-----------------------------------------------");
        System.out.println("MODEL SIGNATURE");
        System.out.println("Inputs:");
        for (Map.Entry<String, TensorInfo> entry : sig.getInputsMap().entrySet()) {
            TensorInfo t = entry.getValue();
            System.out.printf(
                    "%d of %d: %-20s (Node name in graph: %-20s, type: %s)\n",
                    i++, numInputs, entry.getKey(), t.getName(), t.getDtype());
        }
        int numOutputs = sig.getOutputsCount();
        i = 1;
        System.out.println("Outputs:");
        for (Map.Entry<String, TensorInfo> entry : sig.getOutputsMap().entrySet()) {
            TensorInfo t = entry.getValue();
            System.out.printf(
                    "%d of %d: %-20s (Node name in graph: %-20s, type: %s)\n",
                    i++, numOutputs, entry.getKey(), t.getName(), t.getDtype());
        }
        System.out.println("-----------------------------------------------");
    }
}

从java代码中可以看出，我为两个节点提供了输入（用“km1”和“km2”命名）。但我想这不是正确的方法。我猜我需要为节点“input_example_tensor:0”提供输入？

所以问题是：如何实际为加载到 java 中的模型创建输入？在Python中，我必须创建一个带有键“km1”和“km2”的字典，并值两个常量张量。

在 Python 上，尝试

feature_spec = tf.feature_column.make_parse_example_spec(columns)
example_input_fn = tf.estimator.export.build_parsing_serving_input_receiver_fn(feature_spec)

请查看build_parsing_serving_input_receiver_fn，以及一个名为输入示例张量需要序列化的 tf.Example。

在 Java 上，尝试创建一个Example http://static.javadoc.io/org.tensorflow/proto/1.12.0/org/tensorflow/example/package-summary.html输入（封装在org.tensorflow:原型工件 https://mvnrepository.com/artifact/org.tensorflow/proto/1.12.0），以及一些这样的代码：

public static void main(String[] args) {
    Example example = buildExample(yourFeatureNameAndValueMap);
    byte[][] exampleBytes = {example.toByteArray()};
    try (Tensor<String> inputBatch = Tensors.create(exampleBytes);
         Tensor<Float> output =
                 yourSession
                         .runner()
                         .feed(yourInputsName, inputBatch)
                         .fetch(yourOutputsName)
                         .run()
                         .get(0)
                         .expect(Float.class)) {
        long[] shape = output.shape();
        int batchSize = (int) shape[0];
        int labelNum = (int) shape[1];
        float[][] resultValues = output.copyTo(new float[batchSize][labelNum]);
        System.out.println(resultValues);
    }
}

public static Example buildExample(Map<String, ?> yourFeatureNameAndValueMap) {
    Features.Builder builder = Features.newBuilder();
    for (String attr : yourFeatureNameAndValueMap.keySet()) {
        Object value = yourFeatureNameAndValueMap.get(attr);
        if (value instanceof Float) {
            builder.putFeature(attr, feature((Float) value));
        } else if (value instanceof float[]) {
            builder.putFeature(attr, feature((float[]) value));
        } else if (value instanceof String) {
            builder.putFeature(attr, feature((String) value));
        } else if (value instanceof String[]) {
            builder.putFeature(attr, feature((String[]) value));
        } else if (value instanceof Long) {
            builder.putFeature(attr, feature((Long) value));
        } else if (value instanceof long[]) {
            builder.putFeature(attr, feature((long[]) value));
        } else {
            throw new UnsupportedOperationException("Not supported attribute value data type!");
        }
    }
    Features features = builder.build();
    Example example = Example.newBuilder()
            .setFeatures(features)
            .build();
    return example;
}

private static Feature feature(String... strings) {
    BytesList.Builder b = BytesList.newBuilder();
    for (String s : strings) {
        b.addValue(ByteString.copyFromUtf8(s));
    }
    return Feature.newBuilder().setBytesList(b).build();
}

private static Feature feature(float... values) {
    FloatList.Builder b = FloatList.newBuilder();
    for (float v : values) {
        b.addValue(v);
    }
    return Feature.newBuilder().setFloatList(b).build();
}

private static Feature feature(long... values) {
    Int64List.Builder b = Int64List.newBuilder();
    for (long v : values) {
        b.addValue(v);
    }
    return Feature.newBuilder().setInt64List(b).build();
}

如果你想要自动获取您的输入名称 and 你的输出名称， 你可以试试

SignatureDef signatureDef;
try {
    signatureDef = MetaGraphDef.parseFrom(model.metaGraphDef()).getSignatureDefOrThrow(SIGNATURE_DEF_KEY);
} catch (InvalidProtocolBufferException e) {
    throw new RuntimeException(e.getMessage(), e);
}
String yourInputsName = signatureDef.getInputsOrThrow(SIGNATURE_DEF_INPUT_KEY).getName();
String yourOutputsName = signatureDef.getOutputsOrThrow(SIGNATURE_DEF_OUTPUT_KEY).getName();

关于java，请参考检测对象.java https://github.com/tensorflow/models/blob/master/samples/languages/java/object_detection/src/main/java/DetectObjects.java。关于Python，请参考宽_深 https://github.com/tensorflow/models/tree/master/official/wide_deep