1.Deep Learning for Natural Language Processing Using Apache Spark and TensorFlow Alexis Roos – Director Machine Learning @alexisroos Wenhao Liu – Senior Data Scientist Activity Intelligence team
2.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
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6.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
7. Enhance CRM experience using AI and activity Email classification use case Emails, meetings, tasks, calls, etc Extract Insights AI Inbox Suggest Action(s) Insights: Einstein Pricing discussed, Executive Activity involved, Scheduling Requested, Capture Angry email, competition mentioned, etc. Timelines Other Salesforce Apps …
8.What types of emails do Sales users receive? • Emails from customers • Scheduling requests, pricing requests, competitor mentioned, etc. • Emails from coworkers • Marketing emails • Newsletters • Telecom, Spotify, iTunes, Amazon purchases • etc
9.Scheduling requests We want to identify scheduling requests from customers Hi Alexis, Hello Wenhao, Welcome to Business review! Can we get together Can you send me that Your subscription is Thursday afternoon? really important active. document? Best, Your next letter will Thanks, be emailed on May John Mark 25th 2018.
10. Before scoring: filtering and parsing HEADER INFORMATION ... INTRO Hey Alexis, • Right language Let’s meet with Ascander on Friday to discuss BODY the $10,000/year rate. Ascander’s phone • Automated vs non automated number is (123) 456-7890. Thanks, • Inbound / outbound SIGNATURE Noah Bergman Engineer at Salesforce • Within or outside the organization (123) 456-7890 The contents of this email and any attachments • etc CONFIDENTIALITY NOTICE are confidential and are intended solely for addressee… From: Alexis firstname.lastname@example.org Date: April 1, 2017 Subject: Important Document REPLY CHAIN Noah, how much does your product cost?
11.“Basic” NLP text classifier Steps: • Normalize and tokenize • Generate n-grams • Remove stop words • Compute TF with min threshold filter based vocabulary size • Compute IDF and filter n-grams based on IDF threshold Shortcomings: • Lack of generalization as classifier is limited to tokens from training data • Collection of n-grams doesn’t take into account ordering or sequences
12. Word2Vec or GloVe • Unsupervised learning algorithm for obtaining vector representations for words. • Training is performed on aggregated global word-word co-occurrence statistics from a corpus. • Word vectors for individual tokens capture the semantic. word2VecModel.findSynonyms(“cost”, 5) MONEY price license nominal budget
13. High-level Architecture TF/IDF N-gram Feature Extraction Preprocessing Filtering Filtered Or… Text Raw Emails Word2Vec Emails other ML models implemented in Scala/Spark LDA Our current machine learning pipeline is pure Scala / Spark, which has served us well.
14.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
15.What are Neural Networks: feed forward networks “Loose” brain inspiration: structure of cells
16.What are Neural Networks: recurring networks “I grew up in France… I speak fluent French.”
17.LSTM • RNNs suffer from vanishing or exploding gardients • LSTM allow to chain and store and use memory across sequence controlled through gates and operations • Designed to be chained into RNN. https://medium.com/mlreview/understanding-lstm-and-its-diagrams-37e2f46f1714
18.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
19. High Level Model Architecture We present a “simple” BiLSTM model for text classification. Ob0 Of3 • Tokens are mapped into word embeddings (GloVe pretrained on Wikipedia) • The word embedding for each token is fed into both Backward Cb 0 Cb 1 Cb 2 Cb 3 forward and backward recurrent network with LSTM (Long Short-Term Memory*) cells Forward • “Last” output of the forward and backward RNNs are Cf0 Cf1 Cf2 Cf3 concatenated and taken as input by the sigmoid unit for binary classification x0 x1 x2 x3 * Hochreiter & Schmidhuber 1997
20.Detailed Considerations for the Model About dropout and regularization • We applied dropout on recurrent connections* and inputs… • As well as L2 regularization on the model parameters. Ob0 Of3 trainable_vars = tf.trainable_variables() C b0 C b1 C b2 C b3 regularization_loss = tf.reduce_sum( [tf.nn.l2_loss (v) for v in trainable_vars]) Cf0 Cf1 Cf2 Cf3 loss = original_loss + reg_weight * regularization_loss x0 x1 x2 x3 *Gal & Ghahramani NIPS 2016
21.Detailed Considerations for the Model About variable sequence lengths Emails come in different lengths, and some are extremely short while others are long • One-word email: “Thanks” • 800+ words long emails are also commonly seen in business emails tf.nn.dynamic_rnn( cell=lstm_cell, inputs=input_data, sequence_length=seq_len ) Solution: dynamic_rnn + max length + sequence sampling • tf.nn.dynamic_rnn (or tf.nn.bidirectional_dynamic_rnn) allows for variable lengths for input sequences
22.Other Model Architectures Considered We “settled” on current architecture through lots of experiments and considerations. • Single-direction RNN • Single-direction RNN with GRU • Single-direction RNN with LSTM • Average pooling for outputs • Max pooling for all outputs • CNN on top of outputs • …
23.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
24. Fitting a TensorFlow model into a Spark pipeline TF/IDF N-gram Feature Extraction Preprocessing Filtering Filtered Or… Text Raw Emails Word2Vec Emails other ML models implemented in Scala/Spark LDA Our workflow around Spark is completely in Scala/Spark stack • Train a SparkML model in the notebooking environment and save it out • At scoring state, load the pretrained SparkML model (part of SparkML Pipeline), and call the transform method Question: Can we use a TF model as if it was a native Scala/Spark function?
25. Scala/Spark Pipeline + TensorFlow Model TensorFrames / SparkDL as Interface Encoded Input [[10 19853 3920 8425 43 … 18646] Preprocessing Input Tensor Batch Size Filtering Filtered … tf.nn.embedding_lookup Text Raw Emails Emails [235 489 165638 46562 … 16516]] Sequence Length Embedding Matrix Batch Size Vocabulary Size [[0.19853 0.3920 0.8646 0.459 … 0.1865] ng ddi be gth … Sequence Em Len [0.684 0.1894 0.1564 0.9874 … 0.354] ] Length Embedding Length * Shi Yan, Understanding LSTM and its diagrams
26.TensorFrames turns a TensorFlow model into a UDF. Save –> Load –> Score Save the model: %python graph_def = tfx.strip_and_freeze_until(["input_data", "predicted"], sess.graph, sess = sess) tf.train.write_graph(graph_def, “/model”, ”model.pb", False) Load the model: %scala val graph = new com.databricks.sparkdl.python.GraphModelFactory() .sqlContext(sqlContext) .fetches(asJava(Seq("prediction"))) .inputs(asJava(Seq("input_data")), asJava(Seq(”input_data"))) .graphFromFile("/model/model.pb") graph.registerUDF("model") Score with the model: %scala val predictions = inputDataSet.selectExpr("InputData", "model(InputData)")
27.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
28.Agenda Introduction Email Classification Deep Learning Model Architecture TensorFrames/SparkDL Demo Wrap up
29.Lessons Learned • A well-tuned LSTM model can outperform traditional ML approaches • But data preparation is still needed and key to success • Spark can play nicely with TensorFlow using TensorFrame as interface • We can do end-to-end in single notebook and mix Spark/Scala with TF/Python • Model outperforming ML approach and is being productized