用Tensorflow写了一个简易的DNN网络（输入，一个隐层，输出），用作分类，数据集选用的是UCI 的iris数据集
激活函数使用softmax loss函数使用对数似然 以便最后的结果是一个概率解，选概率最大的分类的结果
目前的问题是预测结果出现问题，用测试数据测试显示结果如下
刚刚入门...希望大家指点一下，谢谢辣！
#coding:utf-8
import matplotlib.pyplot as plt
import tensorflow as tf
import numpy as np
import pandas as pd
from sklearn.model_selection import train_test_split
from sklearn.decomposition import PCA
from sklearn import preprocessing
from sklearn.model_selection import cross_val_score
BATCH_SIZE = 30
iris = pd.read_csv('F:\dataset\iris\dataset.data', sep=',', header=None)
'''
# 查看导入的数据
print("Dataset Lenght:: ", len(iris))
print("Dataset Shape:: ", iris.shape)
print("Dataset:: ")
print(iris.head(150))
'''
#将每条数据划分为样本值和标签值
X = iris.values[:, 0:4]
Y = iris.values[:, 4]
# 整理一下标签数据
# Iris-setosa ---> 0
# Iris-versicolor ---> 1
# Iris-virginica ---> 2
for i in range(len(Y)):
if Y[i] == 'Iris-setosa':
Y[i] = 0
elif Y[i] == 'Iris-versicolor':
Y[i] = 1
elif Y[i] == 'Iris-virginica':
Y[i] = 2
# 划分训练集与测试集
X_train, X_test, Y_train, Y_test = train_test_split(X, Y, test_size=0.3, random_state=10)
#对数据集X与Y进行shape整理，让第一个参数为-1表示整理X成n行2列，整理Y成n行1列
X_train = np.vstack(X_train).reshape(-1, 4)
Y_train = np.vstack(Y_train).reshape(-1, 1)
X_test = np.vstack(X_test).reshape(-1, 4)
Y_test = np.vstack(Y_test).reshape(-1, 1)
'''
print(X_train)
print(Y_train)
print(X_test)
print(Y_test)
'''
#定义神经网络的输入，参数和输出，定义前向传播过程
def get_weight(shape):
w = tf.Variable(tf.random_normal(shape), dtype=tf.float32)
return w
def get_bias(shape):
b = tf.Variable(tf.constant(0.01, shape=shape))
return b
x = tf.placeholder(tf.float32, shape=(None, 4))
yi = tf.placeholder(tf.float32, shape=(None, 1))
def BP_Model():
w1 = get_weight([4, 10]) # 第一个隐藏层，10个神经元，4个输入
b1 = get_bias([10])
y1 = tf.nn.softmax(tf.matmul(x, w1) + b1) # 注意维度
w2 = get_weight([10, 3]) # 输出层，3个神经元，10个输入
b2 = get_bias([3])
y = tf.nn.softmax(tf.matmul(y1, w2) + b2)
return y
def train():
# 生成计算图
y = BP_Model()
# 定义损失函数
ce = tf.nn.sparse_softmax_cross_entropy_with_logits(logits=y, labels=tf.arg_max(yi, 1))
loss_cem = tf.reduce_mean(ce)
# 定义反向传播方法，正则化
train_step = tf.train.AdamOptimizer(0.001).minimize(loss_cem)
# 定义保存器
saver = tf.train.Saver(tf.global_variables())
#生成会话
with tf.Session() as sess:
init_op = tf.global_variables_initializer()
sess.run(init_op)
Steps = 5000
for i in range(Steps):
start = (i * BATCH_SIZE) % 300
end = start + BATCH_SIZE
reslut = sess.run(train_step, feed_dict={x: X_train[start:end], yi: Y_train[start:end]})
if i % 100 == 0:
loss_val = sess.run(loss_cem, feed_dict={x: X_train, yi: Y_train})
print("step: ", i, "loss: ", loss_val)
print("保存模型: ", saver.save(sess, './model_iris/bp_model.model'))
tf.summary.FileWriter("logs/", sess.graph)
#train()
def prediction():
# 生成计算图
y = BP_Model()
# 定义损失函数
ce = tf.nn.sparse_softmax_cross_entropy_with_logits(logits=y, labels=tf.arg_max(yi, 1))
loss_cem = tf.reduce_mean(ce)
# 定义保存器
saver = tf.train.Saver(tf.global_variables())
with tf.Session() as sess:
saver.restore(sess, './model_iris/bp_model.model')
result = sess.run(y, feed_dict={x: X_test})
loss_val = sess.run(loss_cem, feed_dict={x: X_test, yi: Y_test})
print("result :", result)
print("loss :", loss_val)
result_set = sess.run(tf.argmax(result, axis=1))
print("predict result: ", result_set)
print("real result: ", Y_test.reshape(1, -1))
#prediction()
