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Getting familiar with TensorFlow
import argparse
import tensorflow as tf
import sys
def flowfib(n):
''' f_n = f_n-1 + f_n-2
Fails in a somewhat interesting way, showing that ints passed to constants are cast to 32 bit signed ints,
causing overflow pretty early in fibonacci sequence.
See for example f_48 = f_47 + f_46
numpy.int32(1134903170) + numpy.int32(1836311903)
__main__:1: RuntimeWarning: overflow encountered in int_scalars
-1323752223
'''
f = [tf.constant(0),tf.constant(1)]
if n>2:
for i in range(2,n):
f_i = f[i-1] + f[i-2]
f.append(f_i)
with tf.Session() as sess:
result = sess.run(f)
print result
def constant_test():
i1, i2, i3, i4 = (tf.constant(1.0),
tf.constant(2.0),
tf.constant(3.0),
tf.constant(4.0))
j1, j2 = (tf.mul(i1,i2), tf.mul(i3,i4))
k = tf.mul(j1,j2)
with tf.Session() as sess:
r = sess.run([k ,j1, j2])
print r
def variable_test():
counter_var = tf.Variable(0, name='counter')
one_const = tf.constant(1)
result = tf.add(counter_var, one_const)
update = tf.assign(counter_var, result)
init_operation = tf.initialize_all_variables()
with tf.Session() as sess:
sess.run(init_operation)
for i in range(5):
print "====="
# counter_var is only updated when output of "update" is retrieved
print "counter variable before update:"
print sess.run([counter_var])
print "counter variable retrieved at same time that we retrieve result of update op:"
print sess.run([counter_var,update])
print "variables that feed into result have not changed, thus retrieving result repeatedly will not yield any different value"
print sess.run([result])
print sess.run([result])
print sess.run([result])
def feed_test(data_one, data_two):
data_placeholder_one = tf.placeholder(tf.types.float32)
data_placeholder_two = tf.placeholder(tf.types.float32)
output = tf.mul(data_placeholder_one, data_placeholder_two)
with tf.Session() as sess:
print sess.run(
[output],
feed_dict={
data_placeholder_one : data_one,
data_placeholder_two : data_two
})
def main(args):
parser = argparse.ArgumentParser(
description='Runs some simple TensorFlow examples.'
)
parser.add_argument('--constant-test',action='store_true')
parser.add_argument('--variable-test',action='store_true')
parser.add_argument('--feed-test',action='store_true')
parser.add_argument('--fib-test',action='store_true')
parsed_args = parser.parse_args(args)
if parsed_args.constant_test:
constant_test()
elif parsed_args.variable_test:
variable_test()
elif parsed_args.feed_test:
feed_test(10.0,20.0)
elif parsed_args.fib_test:
flowfib(50)
if __name__=='__main__':
main(sys.argv[1:])
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