卷积神经网络(CNN)天气识别

文章目录

前期工作

1. 设置GPU(如果使用的是CPU可以忽略这步)

我的环境:

  • 语言环境:Python3.6.5
  • 编译器:jupyter notebook
  • 深度学习环境:TensorFlow2.4.1
python 复制代码
import tensorflow as tf

gpus = tf.config.list_physical_devices("GPU")

if gpus:
    gpu0 = gpus[0]                                        #如果有多个GPU,仅使用第0个GPU
    tf.config.experimental.set_memory_growth(gpu0, True)  #设置GPU显存用量按需使用
    tf.config.set_visible_devices([gpu0],"GPU")

2. 导入数据

python 复制代码
import matplotlib.pyplot as plt
import os,PIL

# 设置随机种子尽可能使结果可以重现
import numpy as np
np.random.seed(1)

# 设置随机种子尽可能使结果可以重现
import tensorflow as tf
tf.random.set_seed(1)

from tensorflow import keras
from tensorflow.keras import layers,models

import pathlib
data_dir = "weather_photos/"
data_dir = pathlib.Path(data_dir)

3. 查看数据

数据集一共分为cloudyrainshinesunrise四类,分别存放于weather_photos文件夹中以各自名字命名的子文件夹中。

python 复制代码
image_count = len(list(data_dir.glob('*/*.jpg')))

print("图片总数为:",image_count)
python 复制代码
roses = list(data_dir.glob('sunrise/*.jpg'))
PIL.Image.open(str(roses[0]))

二、数据预处理

1. 加载数据

使用image_dataset_from_directory方法将磁盘中的数据加载到tf.data.Dataset

batch_size = 32
img_height = 180
img_width = 180
python 复制代码
train_ds = tf.keras.preprocessing.image_dataset_from_directory(
    data_dir,
    validation_split=0.2,
    subset="training",
    seed=123,
    image_size=(img_height, img_width),
    batch_size=batch_size)
Found 1125 files belonging to 4 classes.
Using 900 files for training.

val_ds = tf.keras.preprocessing.image_dataset_from_directory(
    data_dir,
    validation_split=0.2,
    subset="validation",
    seed=123,
    image_size=(img_height, img_width),
    batch_size=batch_size)

Found 1125 files belonging to 4 classes.
Using 225 files for validation.

我们可以通过class_names输出数据集的标签。标签将按字母顺序对应于目录名称。

python 复制代码
class_names = train_ds.class_names
print(class_names)
['cloudy', 'rain', 'shine', 'sunrise']

2. 可视化数据

python 复制代码
plt.figure(figsize=(20, 10))

for images, labels in train_ds.take(1):
    for i in range(20):
        ax = plt.subplot(5, 10, i + 1)

        plt.imshow(images[i].numpy().astype("uint8"))
        plt.title(class_names[labels[i]])
        
        plt.axis("off")

3. 再次检查数据

python 复制代码
for image_batch, labels_batch in train_ds:
    print(image_batch.shape)
    print(labels_batch.shape)
    break
(32, 180, 180, 3)
(32,)
  • Image_batch是形状的张量(32,180,180,3)。这是一批形状180x180x3的32张图片(最后一维指的是彩色通道RGB)。
  • Label_batch是形状(32,)的张量,这些标签对应32张图片

4. 配置数据集

python 复制代码
AUTOTUNE = tf.data.AUTOTUNE

train_ds = train_ds.cache().shuffle(1000).prefetch(buffer_size=AUTOTUNE)
val_ds = val_ds.cache().prefetch(buffer_size=AUTOTUNE)

三、构建CNN网络

卷积神经网络(CNN)的输入是张量 (Tensor) 形式的 (image_height, image_width, color_channels),包含了图像高度、宽度及颜色信息。不需要输入batch size。color_channels 为 (R,G,B) 分别对应 RGB 的三个颜色通道(color channel)。在此示例中,我们的 CNN 输入,fashion_mnist 数据集中的图片,形状是 (28, 28, 1)即灰度图像。我们需要在声明第一层时将形状赋值给参数input_shape

python 复制代码
num_classes = 4

model = models.Sequential([
    layers.experimental.preprocessing.Rescaling(1./255, input_shape=(img_height, img_width, 3)),
    
    layers.Conv2D(16, (3, 3), activation='relu', input_shape=(img_height, img_width, 3)), # 卷积层1,卷积核3*3  
    layers.AveragePooling2D((2, 2)),               # 池化层1,2*2采样
    layers.Conv2D(32, (3, 3), activation='relu'),  # 卷积层2,卷积核3*3
    layers.AveragePooling2D((2, 2)),               # 池化层2,2*2采样
    layers.Conv2D(64, (3, 3), activation='relu'),  # 卷积层3,卷积核3*3
    layers.Dropout(0.3),  
    
    layers.Flatten(),                       # Flatten层,连接卷积层与全连接层
    layers.Dense(128, activation='relu'),   # 全连接层,特征进一步提取
    layers.Dense(num_classes)               # 输出层,输出预期结果
])

model.summary()  # 打印网络结构
Model: "sequential"
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
rescaling (Rescaling)        (None, 180, 180, 3)       0         
_________________________________________________________________
conv2d (Conv2D)              (None, 178, 178, 16)      448       
_________________________________________________________________
average_pooling2d (AveragePo (None, 89, 89, 16)        0         
_________________________________________________________________
conv2d_1 (Conv2D)            (None, 87, 87, 32)        4640      
_________________________________________________________________
average_pooling2d_1 (Average (None, 43, 43, 32)        0         
_________________________________________________________________
conv2d_2 (Conv2D)            (None, 41, 41, 64)        18496     
_________________________________________________________________
dropout (Dropout)            (None, 41, 41, 64)        0         
_________________________________________________________________
flatten (Flatten)            (None, 107584)            0         
_________________________________________________________________
dense (Dense)                (None, 128)               13770880  
_________________________________________________________________
dense_1 (Dense)              (None, 5)                 645       
=================================================================
Total params: 13,795,109
Trainable params: 13,795,109
Non-trainable params: 0
_________________________________________________________________

四、编译

  • 在准备对模型进行训练之前,还需要再对其进行一些设置。以下内容是在模型的编译步骤中添加的:
    • 损失函数(loss):用于衡量模型在训练期间的准确率。

    • 优化器(optimizer):决定模型如何根据其看到的数据和自身的损失函数进行更新。

    • 指标(metrics):用于监控训练和测试步骤。以下示例使用了准确率,即被正确分类的图像的比率。

      设置优化器

      opt = tf.keras.optimizers.Adam(learning_rate=0.001)
      model.compile(optimizer=opt,
      loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
      metrics=['accuracy'])

五、训练模型

epochs = 10
history = model.fit(
  train_ds,
  validation_data=val_ds,
  epochs=epochs
)
python 复制代码
Epoch 1/10
29/29 [==============================] - 6s 58ms/step - loss: 1.5865 - accuracy: 0.4463 - val_loss: 0.5837 - val_accuracy: 0.7689
Epoch 2/10
29/29 [==============================] - 0s 12ms/step - loss: 0.5289 - accuracy: 0.8295 - val_loss: 0.5405 - val_accuracy: 0.8133
Epoch 3/10
29/29 [==============================] - 0s 12ms/step - loss: 0.2930 - accuracy: 0.8967 - val_loss: 0.5364 - val_accuracy: 0.8000
Epoch 4/10
29/29 [==============================] - 0s 12ms/step - loss: 0.2742 - accuracy: 0.9074 - val_loss: 0.4034 - val_accuracy: 0.8267
Epoch 5/10
29/29 [==============================] - 0s 11ms/step - loss: 0.1952 - accuracy: 0.9383 - val_loss: 0.3874 - val_accuracy: 0.8844
Epoch 6/10
29/29 [==============================] - 0s 11ms/step - loss: 0.1592 - accuracy: 0.9468 - val_loss: 0.3680 - val_accuracy: 0.8756
Epoch 7/10
29/29 [==============================] - 0s 12ms/step - loss: 0.0836 - accuracy: 0.9755 - val_loss: 0.3429 - val_accuracy: 0.8756
Epoch 8/10
29/29 [==============================] - 0s 12ms/step - loss: 0.0943 - accuracy: 0.9692 - val_loss: 0.3836 - val_accuracy: 0.9067
Epoch 9/10
29/29 [==============================] - 0s 12ms/step - loss: 0.0344 - accuracy: 0.9909 - val_loss: 0.3578 - val_accuracy: 0.9067
Epoch 10/10
29/29 [==============================] - 0s 11ms/step - loss: 0.0950 - accuracy: 0.9708 - val_loss: 0.4710 - val_accuracy: 0.8356

六、模型评估

python 复制代码
acc = history.history['accuracy']
val_acc = history.history['val_accuracy']

loss = history.history['loss']
val_loss = history.history['val_loss']

epochs_range = range(epochs)

plt.figure(figsize=(12, 4))
plt.subplot(1, 2, 1)
plt.plot(epochs_range, acc, label='Training Accuracy')
plt.plot(epochs_range, val_acc, label='Validation Accuracy')
plt.legend(loc='lower right')
plt.title('Training and Validation Accuracy')

plt.subplot(1, 2, 2)
plt.plot(epochs_range, loss, label='Training Loss')
plt.plot(epochs_range, val_loss, label='Validation Loss')
plt.legend(loc='upper right')
plt.title('Training and Validation Loss')
plt.show()
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