tf.estimator是tensorflow高级API。可以很容易建立神经网络分类器。应用于iris数据集。根据萼片/花瓣的几何描述,进行分类。并且用来预测未知样本属于的花种类。
A training set of 120 samples (iris_training.csv)
A test set of 30 samples (iris_test.csv).
step1,加载数据
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import os
from six.moves.urllib.request import urlopen
import tensorflow as tf
import numpy as np
IRIS_TRAINING = "iris_training.csv"
IRIS_TRAINING_URL = "http://download.tensorflow.org/data/iris_training.csv"
IRIS_TEST = "iris_test.csv"
IRIS_TEST_URL = "http://download.tensorflow.org/data/iris_test.csv"
#下载数据
if not os.path.exists(IRIS_TRAINING):
raw = urlopen(IRIS_TRAINING_URL).read()
with open(IRIS_TRAINING,'wb') as f:
f.write(raw)
if not os.path.exists(IRIS_TEST):
raw = urlopen(IRIS_TEST_URL).read()
with open(IRIS_TEST,'wb') as f:
f.write(raw)
# 加载数据集
training_set = tf.contrib.learn.datasets.base.load_csv_with_header(
filename=IRIS_TRAINING,
target_dtype=np.int,
features_dtype=np.float32)
test_set = tf.contrib.learn.datasets.base.load_csv_with_header(
filename=IRIS_TEST,
target_dtype=np.int,
features_dtype=np.float32)
step2,构建一个深度神经网络分类器
# 数据格式为一维张量
feature_columns = [tf.feature_column.numeric_column("x", shape=[4])]
# 建立一个3层DNN网络,每层节点数10,20,10.
classifier = tf.estimator.DNNClassifier(feature_columns=feature_columns,
hidden_units=[10, 20, 10],
n_classes=3,
model_dir="/tmp/iris_model")
step3,描述输入数据流
# Define the training inputs
train_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"x": np.array(training_set.data)},
y=np.array(training_set.target),
num_epochs=None,
shuffle=True)
step4,将iris数据集填充到DNN分类器中
# Train model.
classifier.train(input_fn=train_input_fn, steps=2000)
等价于:
classifier.train(input_fn=train_input_fn, steps=1000)
classifier.train(input_fn=train_input_fn, steps=1000)
step5,计算模型准确度
# Define the test inputs
test_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"x": np.array(test_set.data)},
y=np.array(test_set.target),
num_epochs=1,
shuffle=False)
# Evaluate accuracy.
accuracy_score = classifier.evaluate(input_fn=test_input_fn)["accuracy"]
print("\nTest Accuracy: {0:f}\n".format(accuracy_score))
step6,预测未知样本
# Classify two new flower samples.
new_samples = np.array(
[[6.4, 3.2, 4.5, 1.5],
[5.8, 3.1, 5.0, 1.7]], dtype=np.float32)
predict_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"x": new_samples},
num_epochs=1,
shuffle=False)
predictions = list(classifier.predict(input_fn=predict_input_fn))
predicted_classes = [p["classes"] for p in predictions]
print(
"New Samples, Class Predictions: {}\n"
.format(predicted_classes))
整理以上代码:
# -*- coding: utf-8 -*-
"""
Created on Tue Dec 19 15:54:41 2017
@author: suncl
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import os
from six.moves.urllib.request import urlopen
import numpy as np
import tensorflow as tf
# Data sets
IRIS_TRAINING = "iris_training.csv"
IRIS_TRAINING_URL = "http://download.tensorflow.org/data/iris_training.csv"
IRIS_TEST = "iris_test.csv"
IRIS_TEST_URL = "http://download.tensorflow.org/data/iris_test.csv"
def main():
# If the training and test sets aren't stored locally, download them.
if not os.path.exists(IRIS_TRAINING):
raw = urlopen(IRIS_TRAINING_URL).read()
with open(IRIS_TRAINING, "wb") as f:
f.write(raw)
if not os.path.exists(IRIS_TEST):
raw = urlopen(IRIS_TEST_URL).read()
with open(IRIS_TEST, "wb") as f:
f.write(raw)
# Load datasets.
training_set = tf.contrib.learn.datasets.base.load_csv_with_header(
filename=IRIS_TRAINING,
target_dtype=np.int,
features_dtype=np.float32)
test_set = tf.contrib.learn.datasets.base.load_csv_with_header(
filename=IRIS_TEST,
target_dtype=np.int,
features_dtype=np.float32)
# Specify that all features have real-value data
feature_columns = [tf.feature_column.numeric_column("x", shape=[4])]
# Build 3 layer DNN with 10, 20, 10 units respectively.
classifier = tf.estimator.DNNClassifier(feature_columns=feature_columns,
hidden_units=[10, 20, 10],
n_classes=3,
model_dir="/tmp/iris_model")
# Define the training inputs
train_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"x": np.array(training_set.data)},
y=np.array(training_set.target),
num_epochs=None,
shuffle=True)
# Train model.
classifier.train(input_fn=train_input_fn, steps=2000)
# Define the test inputs
test_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"x": np.array(test_set.data)},
y=np.array(test_set.target),
num_epochs=1,
shuffle=False)
# Evaluate accuracy.
accuracy_score = classifier.evaluate(input_fn=test_input_fn)["accuracy"]
print("\nTest Accuracy: {0:f}\n".format(accuracy_score))
# Classify two new flower samples.
new_samples = np.array(
[[6.4, 3.2, 4.5, 1.5],
[5.8, 3.1, 5.0, 1.7]], dtype=np.float32)
predict_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"x": new_samples},
num_epochs=1,
shuffle=False)
predictions = list(classifier.predict(input_fn=predict_input_fn))
predicted_classes = [p["classes"] for p in predictions]
print(
"New Samples, Class Predictions: {}\n"
.format(predicted_classes))
if __name__ == "__main__":
main()
本blog结束。