使用TensorBoard
import tensorflow as tf
a=tf.constant(2)
b=tf.constant(3)
x=tf.add(a,b)
with tf.Session() as sess:
writer = tf.summary.FileWriter('./graphs',sess.graph)
print(sess.run(x))
writer.close()
5
（以Anaconda3为例）创建python文件并保存在桌面
python TFtest.py
打开Anaconda Prompt并来到桌面路径下运行PYTHON脚本
tensorboard --logdir="./graphs" --port 6006
运行tensorboad, 它会访问之前脚本创建的graphs文件夹。之后在控制台会显示访问路径。例如 http://WIN10-711010523:6006 将地址粘到浏览器可以看到graph
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接下来将输入节点的名称做一下修改
import tensorflow as tf
a=tf.constant(2,name="a")#用name修改节点名称
b=tf.constant(3,name="b")
x=tf.add(a,b,name="add")
with tf.Session() as sess:
writer = tf.summary.FileWriter('./graphs',sess.graph)
print(sess.run(x))
5
还像之前一样在终端分别运行PYTHON脚本与tensorboard。如果之前浏览器还开着之前tensorboard页面，需要先关闭再重新开启，不然终端会有这样的提示
Found more than one graph event per run, or there was a metagraph containing a graph_def, as well as one or more graph events. Overwriting the graph with the newest event.
Constant 类型
import tensorflow as tf
a=tf.constant([2,2],name='a')#创建constant
b=tf.constant([[0,1],[2,3]],name="b")
add=tf.add(a,b,name="add")
mul=tf.multiply(a,b,name="mul")
with tf.Session() as sess:
x,y=sess.run([add,mul])
print(x,y)
[[2 3]
[4 5]] [[0 2]
[4 6]]
创建constant类型的例子
特殊赋值
zeros=tf.zeros([2,3],tf.int32)
with tf.Session() as sess:
result=sess.run(zeros)
print(result)
[[0 0 0]
[0 0 0]]
创建指定大小的zeros矩阵
input_tensor=tf.constant([[0,1],[2,3],[4,5]],name="input_tensor")
zeros=tf.zeros_like(input_tensor)#指定zeros矩阵的大小
with tf.Session() as sess:
result=sess.run(zeros)
print(result)
[[0 0]
[0 0]
[0 0]]
根据传入的矩阵尺寸创建zeros矩阵
其它类似的函数:
** ones **
- tf.ones(shape,dtype=tf.float32,name=None)
- tf.ones_like(input_tensor,dtype=None,name=None,optimize=True)
matrix=tf.fill([2,3],8)
with tf.Session() as sess:
result=sess.run(matrix)
print(result)
[[8 8 8]
[8 8 8]]
在矩阵内添加指定数值
TF数据类型可以和numpy连用
import numpy as np
tf.int32==np.int32
True
matrix=tf.ones([2,2],np.float32)
with tf.Session() as sess:
result=sess.run(matrix)
print(result)
[[ 1. 1.]
[ 1. 1.]]
tf.Session.run(fetches)
tf数据输出为numpy array
my_const=tf.constant([1.0,2.0],name="my_const")
with tf.Session() as sess:b
print(sess.graph.as_graph_def())
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versions {
producer: 24
}
打印graph def
Variables
Variable 是一个类，constant 是一种op
初始化variable
init=tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
初始化全部variables
init_ab=tf.variables_initializer([a,b],name="init_ab")
with tf.Session() as sess:
sess.run(init_ab)b
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
in ()
1
----> 2 with tf.Session(init_ab=tf.variables_initializer([a,b],name="init_ab")) as sess:
3 sess.run(init_ab)
~\Anaconda3\envs\tensorflow\lib\site-packages\tensorflow\python\ops\variables.py in variables_initializer(var_list, name)
1378 """
1379 if var_list and context.in_graph_mode():
-> 1380 return control_flow_ops.group(*[v.initializer for v in var_list], name=name)
1381 return control_flow_ops.no_op(name=name)
1382
~\Anaconda3\envs\tensorflow\lib\site-packages\tensorflow\python\ops\variables.py in (.0)
1378 """
1379 if var_list and context.in_graph_mode():
-> 1380 return control_flow_ops.group(*[v.initializer for v in var_list], name=name)
1381 return control_flow_ops.no_op(name=name)
1382
AttributeError: 'Tensor' object has no attribute 'initializer'
初始化部分variables但是报错
W=tf.Variable(tf.zeros([784,10]))
with tf.Session() as sess:
sess.run(W.initializer)
初始化单独一个variable
#初始化大小700X100的随机数值矩阵
W=tf.Variable(tf.truncated_normal([700,10]))
with tf.Session() as sess:
sess.run(W.initializer)
print(W)
print(W.eval())
[[-1.64373493 1.38142228 0.02620468 ..., 0.03384978 -1.18727875
-0.30884752]
[ 1.10493028 -0.39550069 -0.03230183 ..., 0.4909828 0.55792344
-1.59890783]
[-0.44164404 0.69113725 -0.86431575 ..., 0.27377507 -1.64605892
0.84873748]
...,
[-1.36063004 0.99020559 0.57447302 ..., -0.20169938 -0.09743395
-1.45789444]
[ 0.30184504 -0.51223069 -1.18259192 ..., -0.5938319 1.26349866
0.19031805]
[ 0.96660119 0.90686685 -1.39591968 ..., 0.13805443 0.88506061
1.22530198]]
Variable的赋值方法
W=tf.Variable(10)
W.assign(100)
with tf.Session() as sess:
sess.run(W.initializer)
print(W.eval())
10
W.assign(100)并没有真正赋值给W，只是做了一下运算。此处需要放在session里才能赋值
W=tf.Variable(10)
assign_op=W.assign(100)
with tf.Session() as sess:
sess.run(W.initializer)
sess.run(assign_op)
print(W.eval())
100
在session加入运算后赋值成功。赋值不用初始化variable因为assign_op一直执行了这一动作。数值初始化本身就是赋值的一类，只不过是专门赋值初始数值的op
#其它赋值方式
my_var=tf.Variable(2,name="my_var")
my_var_times_two=my_var.assign(2*my_var)
with tf.Session() as sess:
sess.run(my_var.initializer)
sess.run(my_var_times_two)#>>4
sess.run(my_var_times_two)#>>8
sess.run(my_var_times_two)#>>16
#其它赋值方式
my_var=tf.Variable(10)
With tf.Session() as sess:
sess.run(my_var.initializer)
sess.run(my_var.assign_add(10))#>>20
sess.run(my_var.assign_sub(2))#>>18
assign_add()与assign_sub()不能初始化variable,只能用my_var的数值
#每个session包含各自的variable
W=tf.Variable(10)
sess1=tf.Session()
sess2=tf.Session()
sess1.run(W.initializer)
sess2.run(W.initializer)
print(sess1.run(W.assign_add(10)))
print(sess2.run(W.assign_sub(2)))
20
8
#每个session包含各自的variable
W=tf.Variable(10)
sess1=tf.Session()
sess2=tf.Session()
sess1.run(W.initializer)
sess2.run(W.initializer)
print(sess1.run(W.assign_add(10)))
print(sess2.run(W.assign_sub(2)))
print(sess1.run(W.assign_add(100)))
print(sess2.run(W.assign_sub(50)))
sess1.close()
sess2.close()
20
8
120
-42
#用一个Variable初始化另一个Variable
#W是个700X100的随机矩阵
W=tf.Variable(tf.truncated_normal([700,10]))
U=tf.Variable(2*W)
Session 与 InteractiveSession
sess = tf.InteractiveSession()
a=tf.constant(5.0)
b=tf.constant(6.0)
c=a*b
print(c.eval()) #在InteractiveSession下，无需像之前那样指定session
sess.close()
30.0
声明tf.InteractiveSession()后无需再次指定session,可以直接运算
Control Dependency
用来指定运算顺序
with g.control_dependencies([a,b,c]):
d= ...
e= ...
#运行顺序仍然是a,b,c
Placeholder 占位
如同公式f(x,y)=x*2+y一样，我们无需知道x,y的确切数值就可以编辑公式
#创建一个placeholder
a=tf.placeholder(tf.float32,shape=[3]) #建议一开始设置好数据类型
b=tf.constant([5,5,5],tf.float32)
c=a+b
with tf.Session() as sess:
print(sess.run(c,{a:[1,2,3]})) #向placeholder传入dict 赋值
#每回只能做一次赋值
[ 6. 7. 8.]
更改op的数值
a=tf.add(2,5)
b=tf.multiply(a,3)
with tf.Session() as sess:
#将a的数值替换为15
replace_dict={a:15}
sess.run(b,feed_dict=replace_dict)#将replace_dict的数值传给feed_dict
Lazy Loading
直到需要时再初始化对象
#普通loading,需要把所有op全部写出来
x=tf.Variable(10,name='x')
y=tf.Variable(20,name='y')
z=tf.add(x,y)
with tf.Session() as sess:
sess.run(tf.global_variables_initializer())
for _ in range(10):
sess.run(z)
#lazy loading
x=tf.Variable(10,name='x')
y=tf.Variable(20,name='y')
with tf.Session() as sess:
sess.run(tf.global_variables_initializer())
for _ in range(10):
sess.run(tf.add(x,y)) #把最后一步运算放到这里
运行千次OP时的建议
- 将op定义与计算/运行分开
- 使用python property 编写function