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import math |
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import numpy as np |
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import tensorflow as tf |
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from ..learning.nn.injectors import SkipGramInjector |
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def sensor2vec(num_sensors, sensor_event_list, embedding_size=20, |
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batch_size=128, num_skips=8, skip_window=5, |
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num_neg_samples=64, learning_rate=1.0): |
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"""Sensor to Vector |
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""" |
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if num_neg_samples > num_sensors: |
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num_neg_samples = num_sensors |
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# Initialize a SkipGram Injector |
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injector = SkipGramInjector(sensor_event_list, batch_size, num_skips, skip_window) |
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# Build Training Model |
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graph = tf.Graph() |
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with graph.as_default(): |
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# Input Place Holder |
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train_inputs = tf.placeholder(tf.int32, shape=[batch_size]) |
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train_labels = tf.placeholder(tf.int32, shape=[batch_size, 1]) |
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# As we normally do not have too many sensors - it is OK to use all of them |
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valid_dataset = tf.constant([i for i in range(num_sensors)], dtype=tf.int32) |
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# Only CPU supports NCE loss |
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with tf.device('/cpu:0'): |
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# Look up embeddings for inputs. |
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embeddings = tf.Variable( |
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tf.random_uniform([num_sensors, embedding_size], -1.0, 1.0)) |
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embed = tf.nn.embedding_lookup(embeddings, train_inputs) |
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# Construct the variables for the NCE loss |
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nce_weights = tf.Variable( |
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tf.truncated_normal([num_sensors, embedding_size], |
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stddev=1.0 / math.sqrt(embedding_size))) |
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nce_biases = tf.Variable(tf.zeros([num_sensors])) |
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# Compute the average NCE loss for the batch. |
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# tf.nce_loss automatically draws a new sample of the negative labels each |
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# time we evaluate the loss. |
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loss = tf.reduce_mean( |
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tf.nn.nce_loss(weights=nce_weights, |
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biases=nce_biases, |
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labels=train_labels, |
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inputs=embed, |
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num_sampled=num_neg_samples, |
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num_classes=num_sensors)) |
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# Construct the Optimizer |
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optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(loss) |
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# Compute the cosine similarity between minibatch examples and all embeddings. |
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norm = tf.sqrt(tf.reduce_sum(tf.square(embeddings), 1, keep_dims=True)) |
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normalized_embeddings = embeddings / norm |
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valid_embeddings = tf.nn.embedding_lookup( |
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normalized_embeddings, valid_dataset) |
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similarity = tf.matmul( |
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valid_embeddings, normalized_embeddings, transpose_b=True) |
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# Add variable initializer. |
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init = tf.initialize_all_variables() |
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# Begin training. |
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num_steps = 100001 |
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with tf.Session(graph=graph) as session: |
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# We must initialize all variables before we use them. |
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init.run() |
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print("Initialized") |
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average_loss = 0 |
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for step in range(num_steps): |
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batch_inputs, batch_labels = injector.next_batch() |
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feed_dict = {train_inputs: batch_inputs, train_labels: batch_labels} |
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# We perform one update step by evaluating the optimizer op (including it |
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# in the list of returned values for session.run() |
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_, loss_val = session.run([optimizer, loss], feed_dict=feed_dict) |
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average_loss += loss_val |
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if step % 2000 == 0: |
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if step > 0: |
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average_loss /= 2000 |
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# The average loss is an estimate of the loss over the last 2000 batches. |
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print("Average loss at step ", step, ": ", average_loss) |
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average_loss = 0 |
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final_embeddings = normalized_embeddings.eval() |
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final_similarity = 1 - similarity.eval() |
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distance_matrix = final_similarity / np.max(final_similarity, axis=1)[:, None] |
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return final_embeddings, distance_matrix |
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def sensor2vec_data(sensor_list, event_list, embedding_size=20, |
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batch_size=128, num_skips=8, skip_window=5, |
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num_neg_samples=64, learning_rate=1.0, ignore_off=True): |
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"""Transform sensor to high dimensional space |
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Similar to word embedding used in natural language processing system, we want |
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to represent sensors using in a synthesized vector space as well, instead of |
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using an arbitrary labels for each sensors without any useful information. |
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The methods used to find word embeddings can be classified into two categories: |
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count-based methods (Latent Semantic Analysis) and predictive models. |
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In this implementation for mapping sensor into high dimension vector space, we |
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use skip-gram negative sampling models. |
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Args: |
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sensor_list (:obj:`list` of :obj:`dict`): List of dictionary containing |
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sensor information. |
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event_list (:obj:`list` of :obj:`dict`): List of events. |
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embedding_size (:obj:`int`): The size of embedding vector. |
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batch_size (:obj:`int`): The number of batch used in training |
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num_skips (:obj:`int`): How many times to re-use an input to generate a label |
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in skip-gram model. |
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skip_window (:obj:`int`): How many items to consider left or right in skip-gram |
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model. |
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num_neg_samples (:obj:`int`): Number of negative samples to draw from the vocabulary. |
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ignore_off (:obj:`bool`): Ignore motion-sensor with ``Off`` state in event.rst list. |
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Please refer to :func:`sensor_distance` for an example of ``sensor_list``. |
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Please refer to :func:`sensor_mi_distance` for an example of ``event_list``. |
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""" |
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# Put sensor in hash table for fast fetch of index |
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num_sensors = len(sensor_list) |
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# Negative samples cannot exceed sensor numbers |
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if num_neg_samples > num_sensors: |
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num_neg_samples = num_sensors |
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# Store sensor ID in hash table for faster access |
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sensor_dict = {} |
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for i in range(num_sensors): |
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sensor_dict[sensor_list[i]['name']] = i |
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# Generate event.rst sensor list |
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event_sensor_list = [] |
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for event_entry in event_list: |
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if ignore_off and event_entry['sensor_status'].upper() == "OFF": |
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continue |
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event_sensor_list.append(sensor_dict[event_entry['sensor_id']]) |
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# Initialize a SkipGram Injector |
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injector = SkipGramInjector(event_sensor_list, batch_size, num_skips, skip_window) |
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# Build Training Model |
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graph = tf.Graph() |
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with graph.as_default(): |
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# Input Place Holder |
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train_inputs = tf.placeholder(tf.int32, shape=[batch_size]) |
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train_labels = tf.placeholder(tf.int32, shape=[batch_size, 1]) |
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# As we normally do not have too many sensors - it is OK to use all of them |
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valid_dataset = tf.constant([i for i in range(num_sensors)], dtype=tf.int32) |
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# Only CPU supports NCE loss |
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with tf.device('/cpu:0'): |
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# Look up embeddings for inputs. |
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embeddings = tf.Variable( |
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tf.random_uniform([num_sensors, embedding_size], -1.0, 1.0)) |
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embed = tf.nn.embedding_lookup(embeddings, train_inputs) |
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# Construct the variables for the NCE loss |
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nce_weights = tf.Variable( |
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tf.truncated_normal([num_sensors, embedding_size], |
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stddev=1.0 / math.sqrt(embedding_size))) |
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nce_biases = tf.Variable(tf.zeros([num_sensors])) |
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# Compute the average NCE loss for the batch. |
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# tf.nce_loss automatically draws a new sample of the negative labels each |
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# time we evaluate the loss. |
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loss = tf.reduce_mean( |
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tf.nn.nce_loss(weights=nce_weights, |
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biases=nce_biases, |
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labels=train_labels, |
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inputs=embed, |
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num_sampled=num_neg_samples, |
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num_classes=num_sensors)) |
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# Construct the Optimizer |
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optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(loss) |
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# Compute the cosine similarity between minibatch examples and all embeddings. |
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norm = tf.sqrt(tf.reduce_sum(tf.square(embeddings), 1, keep_dims=True)) |
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normalized_embeddings = embeddings / norm |
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valid_embeddings = tf.nn.embedding_lookup( |
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normalized_embeddings, valid_dataset) |
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similarity = tf.matmul( |
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valid_embeddings, normalized_embeddings, transpose_b=True) |
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# Add variable initializer. |
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init = tf.initialize_all_variables() |
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# Begin training. |
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num_steps = 100001 |
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with tf.Session(graph=graph) as session: |
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# We must initialize all variables before we use them. |
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init.run() |
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print("Initialized") |
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average_loss = 0 |
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for step in range(num_steps): |
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batch_inputs, batch_labels = injector.next_batch() |
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feed_dict = {train_inputs: batch_inputs, train_labels: batch_labels} |
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# We perform one update step by evaluating the optimizer op (including it |
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# in the list of returned values for session.run() |
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_, loss_val = session.run([optimizer, loss], feed_dict=feed_dict) |
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average_loss += loss_val |
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if step % 2000 == 0: |
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if step > 0: |
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average_loss /= 2000 |
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# The average loss is an estimate of the loss over the last 2000 batches. |
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print("Average loss at step ", step, ": ", average_loss) |
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average_loss = 0 |
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# Note that this is expensive (~20% slowdown if computed every 500 steps) |
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if step % 10000 == 0: |
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sim = similarity.eval() |
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for i in range(num_sensors): |
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valid_sensor = sensor_list[i]['name'] |
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top_k = 8 # number of nearest neighbors |
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nearest = (-sim[i, :]).argsort()[1:top_k + 1] |
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log_str = "Nearest to %s:" % valid_sensor |
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for k in range(top_k): |
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close_sensor = sensor_list[nearest[k]]['name'] |
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log_str = "%s %s," % (log_str, close_sensor) |
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print(log_str) |
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final_embeddings = normalized_embeddings.eval() |
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final_similarity = 1 - similarity.eval() |
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distance_matrix = final_similarity / np.max(final_similarity, axis=1)[:,None] |
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# try: |
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# from sklearn.manifold import TSNE |
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# import matplotlib.pyplot as plt |
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# |
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# tsne = TSNE(perplexity=30, n_components=2, init='pca', n_iter=5000) |
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# low_dim_embs = tsne.fit_transform(final_embeddings) |
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# labels = [sensor_list[i]['name'] for i in range(num_sensors)] |
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# |
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# assert low_dim_embs.shape[0] >= len(labels), "More labels than embeddings" |
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# plt.figure(figsize=(18, 18)) # in inches |
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# for i, label in enumerate(labels): |
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# x, y = low_dim_embs[i, :] |
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# plt.scatter(x, y) |
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# plt.annotate(label, |
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# xy=(x, y), |
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# xytext=(5, 2), |
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# textcoords='offset points', |
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# ha='right', |
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# va='bottom') |
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# plt.show() |
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# except ImportError: |
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# print("Please install sklearn, matplotlib, and scipy to visualize embeddings.") |
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return final_embeddings, distance_matrix |
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