我需要一些帮助来确定我遇到的性能问题。我正在使用https://codesachin.wordpress.com/2015/11/28/self-organizing-maps-with-googles-tensorflow/中的代码作为自组织地图的基础。此代码在 CPU 上运行 10 秒，在 GPU 上运行 40 秒。我激活了日志并修改了代码以关联张量板中变量的名称，但我无法确定导致此性能问题的原因。你能告诉我可能发生了什么吗？我已将代码转换为在最新版本的 Tensorflow 中运行。
谢谢您的帮助。
按照代码更改。
import tensorflow as tf
import numpy as np
class SOM(object):
"""
2-D Self-Organizing Map with Gaussian Neighbourhood function
and linearly decreasing learning rate.
"""
# To check if the SOM has been trained
_trained = False
def __init__(self, m, n, dim, n_iterations=100, alpha=None, sigma=None):
""""
Initializes all necessary components of the TensorFlow
Graph.
m X n are the dimensions of the SOM. 'n_iterations' should
should be an integer denoting the number of iterations undergone
while training.
'dim' is the dimensionality of the training inputs.
'alpha' is a number denoting the initial time(iteration no)-based
learning rate. Default value is 0.3
'sigma' is the the initial neighbourhood value, denoting
the radius of influence of the BMU while training. By default, its
taken to be half of max(m, n).
"""
# Assign required variables first
self._m = m
self._n = n
if alpha is None:
alpha = 0.3
else:
alpha = float(alpha)
if sigma is None:
sigma = max(m, n) / 2.0
else:
sigma = float(sigma)
self._n_iterations = abs(int(n_iterations))
##INITIALIZE GRAPH
self._graph = tf.Graph()
##POPULATE GRAPH WITH NECESSARY COMPONENTS
with self._graph.as_default():
##VARIABLES AND CONSTANT OPS FOR DATA STORAGE
# Randomly initialized weightage vectors for all neurons,
# stored together as a matrix Variable of size [m*n, dim]
self._weightage_vects = tf.Variable(tf.random_normal(
[m * n, dim]))
# Matrix of size [m*n, 2] for SOM grid locations
# of neurons
self._location_vects = tf.constant(np.array(
list(self._neuron_locations(m, n))))
##PLACEHOLDERS FOR TRAINING INPUTS
# We need to assign them as attributes to self, since they
# will be fed in during training
# The training vector
self._vect_input = tf.placeholder("float", [dim])
# Iteration number
self._iter_input = tf.placeholder("float")
##CONSTRUCT TRAINING OP PIECE BY PIECE
# Only the final, 'root' training op needs to be assigned as
# an attribute to self, since all the rest will be executed
# automatically during training
# To compute the Best Matching Unit given a vector
# Basically calculates the Euclidean distance between every
# neuron's weightage vector and the input, and returns the
# index of the neuron which gives the least value
bmu_index = tf.argmin(tf.sqrt(tf.reduce_sum(
tf.pow(tf.subtract(self._weightage_vects, tf.stack(
[self._vect_input for i in range(m * n)])), 2), 1)),
0)
# This will extract the location of the BMU based on the BMU's
# index
slice_input = tf.pad(tf.reshape(bmu_index, [1]),
np.array([[0, 1]]))
bmu_loc = tf.reshape(tf.slice(self._location_vects, slice_input,
tf.constant(np.array([1, 2]), dtype=tf.int64)),
[2])
# To compute the alpha and sigma values based on iteration
# number
learning_rate_op = tf.subtract(1.0, tf.div(self._iter_input,
self._n_iterations))
_alpha_op = tf.multiply(alpha, learning_rate_op)
_sigma_op = tf.multiply(sigma, learning_rate_op)
# Construct the op that will generate a vector with learning
# rates for all neurons, based on iteration number and location
# wrt BMU.
bmu_distance_squares = tf.reduce_sum(tf.pow(tf.subtract(
self._location_vects, tf.stack(
[bmu_loc for i in range(m * n)])), 2), 1)
neighbourhood_func = tf.exp(tf.negative(tf.div(tf.cast(
bmu_distance_squares, "float32"), tf.pow(_sigma_op, 2))))
learning_rate_op = tf.multiply(_alpha_op, neighbourhood_func)
# Finally, the op that will use learning_rate_op to update
# the weightage vectors of all neurons based on a particular
# input
learning_rate_multiplier = tf.stack([tf.tile(tf.slice(
learning_rate_op, np.array([i]), np.array([1])), [dim])
for i in range(m * n)])
weightage_delta = tf.multiply(
learning_rate_multiplier,
tf.subtract(tf.stack([self._vect_input for i in range(m * n)]),
self._weightage_vects))
new_weightages_op = tf.add(self._weightage_vects,
weightage_delta)
self._training_op = tf.assign(self._weightage_vects,
new_weightages_op)
##INITIALIZE SESSION
self._sess = tf.Session(config=tf.ConfigProto(log_device_placement=True))
##INITIALIZE VARIABLES
init_op = tf.global_variables_initializer()
self._sess.run(init_op)
def _neuron_locations(self, m, n):
"""
Yields one by one the 2-D locations of the individual neurons
in the SOM.
"""
# Nested iterations over both dimensions
# to generate all 2-D locations in the map
for i in range(m):
for j in range(n):
yield np.array([i, j])
def train(self, input_vects):
"""
Trains the SOM.
'input_vects' should be an iterable of 1-D NumPy arrays with
dimensionality as provided during initialization of this SOM.
Current weightage vectors for all neurons(initially random) are
taken as starting conditions for training.
"""
# Training iterations
for iter_no in range(self._n_iterations):
# Train with each vector one by one
for input_vect in input_vects:
self._sess.run(self._training_op,
{self._vect_input: input_vect,
self._iter_input: iter_no})
# Store a centroid grid for easy retrieval later on
centroid_grid = [[] for i in range(self._m)]
self._weightages = list(self._sess.run(self._weightage_vects))
self._locations = list(self._sess.run(self._location_vects))
for i, loc in enumerate(self._locations):
centroid_grid[loc[0]].append(self._weightages[i])
self._centroid_grid = centroid_grid
self._trained = True
def get_centroids(self):
"""
Returns a list of 'm' lists, with each inner list containing
the 'n' corresponding centroid locations as 1-D NumPy arrays.
"""
if not self._trained:
raise ValueError("SOM not trained yet")
return self._centroid_grid
def map_vects(self, input_vects):
"""
Maps each input vector to the relevant neuron in the SOM
grid.
'input_vects' should be an iterable of 1-D NumPy arrays with
dimensionality as provided during initialization of this SOM.
Returns a list of 1-D NumPy arrays containing (row, column)
info for each input vector(in the same order), corresponding
to mapped neuron.
"""
if not self._trained:
raise ValueError("SOM not trained yet")
to_return = []
for vect in input_vects:
min_index = min([i for i in range(len(self._weightages))],
key=lambda x: np.linalg.norm(vect -
self._weightages[x]))
to_return.append(self._locations[min_index])
return to_return
def write(self):
writer = tf.summary.FileWriter('/tmp/tensorflow_logs', graph=self._sess.graph)
# For plotting the images
from matplotlib import pyplot as plt
# Training inputs for RGBcolors
colors = np.array(
[[0., 0., 0.],
[0., 0., 1.],
[0., 0., 0.5],
[0.125, 0.529, 1.0],
[0.33, 0.4, 0.67],
[0.6, 0.5, 1.0],
[0., 1., 0.],
[1., 0., 0.],
[0., 1., 1.],
[1., 0., 1.],
[1., 1., 0.],
[1., 1., 1.],
[.33, .33, .33],
[.5, .5, .5],
[.66, .66, .66]])
color_names = \
['black', 'blue', 'darkblue', 'skyblue',
'greyblue', 'lilac', 'green', 'red',
'cyan', 'violet', 'yellow', 'white',
'darkgrey', 'mediumgrey', 'lightgrey']
with tf.device("/cpu:0"):
# Train a 20x30 SOM with 400 iterations
som = SOM(20, 30, 3, 400)
som.train(colors)
# Get output grid
image_grid = som.get_centroids()
# Map colours to their closest neurons
mapped = som.map_vects(colors)
# Plot
plt.imshow(image_grid)
plt.title('Color SOM')
for i, m in enumerate(mapped):
plt.text(m[1], m[0], color_names[i], ha='center', va='center',
bbox=dict(facecolor='white', alpha=0.5, lw=0))
plt.show()
som.write()