import numpy as np import imageio def preprocess_input(x, v2=True): x = x.astype('float32') x = x / 255.0 if v2: x = x - 0.5 x = x * 2.0 return x

这是一段Python代码，用于数据预处理。下面是对代码的解释：

import numpy as np 
import imageio 

def preprocess_input(x, v2=True): 
    x = x.astype('float32') # 将输入数据类型转换为浮点型
    x = x / 255.0           # 将数据归一化到[0, 1]范围内
    if v2:                  # 如果v2为True
        x = x - 0.5         # 将数据中心化到0附近
        x = x * 2.0         # 将数据放大到[-1, 1]范围内
    return x                # 返回处理后的数据

这段代码依赖于NumPy和imageio库。`preprocess_input`函数的输入`x`是一组数据，输出也是一组处理后的数据。函数将输入数据的类型转换为浮点型，然后将它们归一化到[0, 1]的范围内。如果`v2`为True，则将数据中心化到0附近，然后将其放大到[-1, 1]的范围内。最后，函数返回处理后的数据。这个函数可以用于图像处理、深度学习等领域。

相关问题

import numpy as np import matplotlib.pyplot as plt def plot_trig_function(trig_func, start, end, step): x = np.arange(start, end, step) if trig_func == 'sin': y = np.sin(x) elif trig_func == 'cos': y = np.cos(x) elif trig_func == 'tan': y = np.tan(x) else: print('Invalid trig function') return plt.plot(x, y) plt.xlabel('x') plt.ylabel(trig_func + '(x)') plt.title(trig_func + ' function') plt.show()

这是我为您编写的程序，可以根据输入的三角函数类型和参数，绘制相应的曲线。您可以根据需要调整起始点、终止点和点数，以及选择其他三角函数来绘制相应的曲线。

示例代码：

import numpy as np
import matplotlib.pyplot as plt

def plot_trig_function(trig_func, start, end, step):
    x = np.arange(start, end, step)
    if trig_func == 'sin':
        y = np.sin(x)
    elif trig_func == 'cos':
        y = np.cos(x)
    elif trig_func == 'tan':
        y = np.tan(x)
    else:
        print('Invalid trig function')
        return
    plt.plot(x, y)
    plt.xlabel('x')
    plt.ylabel(trig_func + '(x)')
    plt.title(trig_func + ' function')
    plt.show()

# 绘制sin函数从0到2π的曲线
plot_trig_function('sin', 0, 2*np.pi, 0.1)

输出结果为：


import pandas as pd import warnings import sklearn.datasets import sklearn.linear_model import matplotlib import matplotlib.font_manager as fm import matplotlib.pyplot as plt import numpy as np import seaborn as sns data = pd.read_excel(r'C:\Users\Lenovo\Desktop\data.xlsx') print(data.info()) fig = plt.figure(figsize=(10, 8)) sns.heatmap(data.corr(), cmap="YlGnBu", annot=True) plt.title('相关性分析热力图') plt.rcParams['axes.unicode_minus'] = False plt.rcParams['font.sans-serif'] = 'SimHei' plt.show() y = data['y'] x = data.drop(['y'], axis=1) print('************************输出新的特征集数据***************************') print(x.head()) from sklearn.model_selection import train_test_split x_train, x_test, y_train, y_test = train_test_split(x, y, test_size=0.2, random_state=42) def relu(x): output=np.maximum(0, x) return output def relu_back_propagation(derror_wrt_output,x): derror_wrt_dinputs = np.array(derror_wrt_output, copy=True) derror_wrt_dinputs[x <= 0] = 0 return derror_wrt_dinputs def activated(activation_choose,x): if activation_choose == 'relu': return relu(x) def activated_back_propagation(activation_choose, derror_wrt_output, output): if activation_choose == 'relu': return relu_back_propagation(derror_wrt_output, output) class NeuralNetwork: def __init__(self, layers_strcuture, print_cost = False): self.layers_strcuture = layers_strcuture self.layers_num = len(layers_strcuture) self.param_layers_num = self.layers_num - 1 self.learning_rate = 0.0618 self.num_iterations = 2000 self.x = None self.y = None self.w = dict() self.b = dict() self.costs = [] self.print_cost = print_cost self.init_w_and_b() def set_learning_rate(self,learning_rate): self.learning_rate=learning_rate def set_num_iterations(self, num_iterations): self.num_iterations = num_iterations def set_xy(self, input, expected_output): self.x = input self.y = expected_output

这段代码存在两个问题：

1. 在import语句中没有使用逗号分隔符，应该在每个import语句之间添加逗号分隔符。
2. 在函数set_xy()的定义中，函数体没有缩进，应该在函数体内部添加缩进。

以下是修改后的代码：

import pandas as pd, warnings
import sklearn.datasets, sklearn.linear_model
import matplotlib, matplotlib.font_manager as fm
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns

data = pd.read_excel(r'C:\Users\Lenovo\Desktop\data.xlsx')
print(data.info())

fig = plt.figure(figsize=(10, 8))
sns.heatmap(data.corr(), cmap="YlGnBu", annot=True)
plt.title('相关性分析热力图')
plt.rcParams['axes.unicode_minus'] = False
plt.rcParams['font.sans-serif'] = 'SimHei'
plt.show()

y = data['y']
x = data.drop(['y'], axis=1)

print('************************输出新的特征集数据***************************')
print(x.head())

from sklearn.model_selection import train_test_split
x_train, x_test, y_train, y_test = train_test_split(x, y, test_size=0.2, random_state=42)

def relu(x):
    output=np.maximum(0, x)
    return output

def relu_back_propagation(derror_wrt_output,x):
    derror_wrt_dinputs = np.array(derror_wrt_output, copy=True)
    derror_wrt_dinputs[x <= 0] = 0
    return derror_wrt_dinputs

def activated(activation_choose,x):
    if activation_choose == 'relu':
        return relu(x)

def activated_back_propagation(activation_choose, derror_wrt_output, output):
    if activation_choose == 'relu':
        return relu_back_propagation(derror_wrt_output, output)

class NeuralNetwork:
    def __init__(self, layers_strcuture, print_cost = False):
        self.layers_strcuture = layers_strcuture
        self.layers_num = len(layers_strcuture)
        self.param_layers_num = self.layers_num - 1
        self.learning_rate = 0.0618
        self.num_iterations = 2000
        self.x = None
        self.y = None
        self.w = dict()
        self.b = dict()
        self.costs = []
        self.print_cost = print_cost
        self.init_w_and_b()
    
    def set_learning_rate(self,learning_rate):
        self.learning_rate=learning_rate 
    
    def set_num_iterations(self, num_iterations):
        self.num_iterations = num_iterations 
    
    def set_xy(self, input, expected_output):
        self.x = input
        self.y = expected_output