[开发技巧]·AttributeError: module 'pywt' has no attribute 'wavedec'解决方法 1.卸载 pywt pip uninstall pywt 2.安装
二,在python中使用小波分析进行阈值去噪声,使用pywt.threshold函数 #coding=gbk #使用小波分析进行阈值去噪声,使用pywt.threshold import pywt ] # pywt.threshold(data, value, mode, substitute) mode 模式有4种,soft, hard, greater, less; substitute 是替换值 data_soft = pywt.threshold(data=data, value=6, mode='soft', substitute=12) print(data_soft) 将小于6 的值设置为12, 大于等于6 的值全部减去6 data_hard = pywt.threshold(data=data, value=6, mode='hard', substitute 将小于6 的值设置为12, 其余的值不变 data_greater = pywt.threshold(data, 6, 'greater', 12) print(data_greater)
当遇到类似module ‘pywt’ has no attribute ‘wavedec’之类的错误的时候. 例如: AttributeError: module 'pywt' has no attribute 'wavedec2' 按下面的步骤走一遍就可以: 步骤: 1、打开cmd终端或Anaconda3终端 2、输入 pip uninstall pywt 。 3、输入pip install PyWavelets 。 问题解决。
(Python Wavelets)库实现DWT,这是工业界常用的小波库; pywt.wavedec():对信号进行小波分解,返回近似系数和各层细节系数; pywt.waverec():根据分解系数重构原始信号 库FWT(对比验证) pywt_coeffs = pywt.wavedec(signal, 'haar', level=2) # 可视化 plt.figure(figsize=(10, 6)) plt.subplot 库结果是否一致 print("自定义FWT系数:", fwt_coeffs) print("pywt库FWT系数:", pywt_coeffs) 代码说明 快速小波变换的核心是“卷积+下采样”:先用低通 pywt.threshold(cD2, threshold, mode='soft') cH1_denoise = pywt.threshold(cH1, threshold, mode='soft' ) cV1_denoise = pywt.threshold(cV1, threshold, mode='soft') cD1_denoise = pywt.threshold(cD1, threshold
小波变换的Python实现 我在查博客的时候,看到有些代码用pywt.dwt,有些用pywt.wavedec,还有一些用pywt.cwt,专门查了一下,三者的区别具体如下: pywt.dwt:执行一级离散小波变换 pywt.wavedec:执行多级离散小波变换。它会对信号进行多次分解,每一级都将上一级得到的近似系数进一步分解为新的近似系数和细节系数,最终得到不同尺度下的近似系数和各级细节系数。 pywt.cwt:执行连续小波变换。输入包括信号signal、尺度scale、小波基等。 pywt.dwt函数会返回一个包含两个元素的元组,这两个元素分别是近似系数(Approximation coefficients)和细节系数(Detail coefficients),并将其赋值给变量 2.3 使用pywt.cwt进行连续小波变换 import numpy as np import matplotlib.pyplot as plt import pywt from pywt import
由于最近正好在学习用python进行小波分解,看的英文的pywt库的各种属性和方法及其使用示例,在这里记录下来,方便以后查阅,前面的小波分解部分忘了记录了,就只能从小波包分解开始了。 小波包: 首先导入pywt库: >>> import pywt 一、创建小波包结构: 接下来我们实例化一个小波包对象: >>> x = [1, 2, 3, 4, 5, 6, 7, 8] >>> wp = pywt.WaveletPacket(data=x, wavelet='db1', mode='symmetric') 输入数据和分解系数(细节系数和逼近系数)都可以通过WaveletPacket.data >>> x = [1, 2, 3, 4, 5, 6, 7, 8] >>> wp = pywt.WaveletPacket(data=x, wavelet='db1', mode='symmetric') 注意:本节仅用于演示pywt的内部组件。不要依懒于本例中所示的对节点的属性访问。
,你的 values 少了 结论 你要赋值的变量多了,你的 values 少了,这是根本原因,就比如 a, b, c, d = 20, 5, 5 就会报错 我的出错代码 import pywt = excel2matrix(pathX) a = np.mean(x) print(a) w = 'sym4' # 小波基类型 l = 3 # 小波变换层次 coeffs = pywt.wavedec2 , cD1)] = coeffs 这个代码报错 ValueError: too many values to unpack (expected 4) 原因 调用 pywt.wavedec2 时参数错误,其大概形式如下 pywt.wavedec2(data, wavelet, mode=’symmetric’, level=None, axes=(-2, -1)) data: cD2), (cH1, cV1, cD1)] 为什么会错呢,因为我直接使用了参数位置匹配,但是中间有一个 mode=’symmetric’ 我没有指定,自然错了所以换成 coeffs = pywt.wavedec2
np.array([1.11,2.22,3.33]) #数据类型转换用astype,数组长度不会变 a=a.astype(np.int8) print(a) [1 2 3] 再来看看实例: import pywt (img, 'db6',level=2) coefs[1]=np.zeros_like(coefs[1]) coefs[2]=np.zeros_like(coefs[2]) con_img=pywt.waverec2 import pywt import numpy as np import matplotlib.pyplot as plt import cv2 img=cv2.imread(r'F:\picture_test \13.jpg') img=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) img=cv2.resize(img,(512,512)) coefs=pywt.wavedec2( img, 'db6',level=2) coefs[1]=np.zeros_like(coefs[1]) coefs[2]=np.zeros_like(coefs[2]) con_img=pywt.waverec2
torch.as_tensor(ch1).contiguous().to(device=device, dtype=torch.float32), pywt.Wavelet torch.as_tensor(ch2).contiguous().to(device=device, dtype=torch.float32), pywt.Wavelet torch.as_tensor(ch3).contiguous().to(device=device, dtype=torch.float32), pywt.Wavelet = reconstruction.detach().cpu().squeeze().numpy() return reconstruction python版本(cpu)代码 import pywt (ch1, 'haar', level=1) cooef2 = pywt.wavedec2(ch2, 'haar', level=1) cooef3 = pywt.wavedec2(ch3
使用Python中的PyWavelets库实现信号小波分解和重构步骤说明导入库:使用pywt进行小波变换,numpy处理数据,matplotlib绘图生成示例信号:创建包含多个频率成分的合成信号小波分解 执行小波分解coeffs = pywt.wavedec(signal, wavelet, level=level)cA4, cD4, cD3, cD2, cD1 = coeffs # 各级系数print coeffs_thresh = [coeffs[0]] # 保留近似系数for i in range(1, len(coeffs)): # 对细节系数应用软阈值 coeffs_thresh.append(pywt.threshold 信号重构reconstructed = pywt.waverec(coeffs_thresh, wavelet)# 确保信号长度一致(小波变换可能导致边界扩展)reconstructed = reconstructed ':Daubechies 4阶小波(常用)其他选项:'haar', 'sym5', 'coif3'等(根据信号特性选择)分解层数:通常选择使最低频分量有足够代表性的层数最大层数限制:level <= pywt.dwt_max_level
pip install ptwt python版本(cuda加速)代码 import pywt import ptwt import torch import numpy as np import SimpleITK torch.as_tensor(ch1).contiguous().to(device=device, dtype=torch.float32), pywt.Wavelet torch.as_tensor(ch2).contiguous().to(device=device, dtype=torch.float32), pywt.Wavelet = reconstruction.detach().cpu().squeeze().numpy() return reconstruction python版本(cpu)代码 import pywt (ch1, 'haar', level=1) cooef2 = pywt.wavedecn(ch2, 'haar', level=1) fusedCooef = [] for i
pip install PyWavelets python版本代码: import pywt import cv2 import numpy as np import math from scipy import I2 = cv2.imread('VIS1.png', 0) # First: Do wavelet transform on each image wavelet = 'db2' cooef1 = pywt.wavedec2 (I1[:, :], wavelet, level=1) cooef2 = pywt.wavedec2(I2[:, :], wavelet, level=1) # Second: for each level c3)) # Third: After we fused the cooefficent we nned to transfor back to get the image fusedImage = pywt.waverec2
pip install PyWavelets python版本代码: import pywt import numpy as np import SimpleITK as sitk # This function cgau4, cgau5, cgau6, cgau7, cgau8 shan family: shan fbsp family: fbsp cmor family: cmor """ cooef1 = pywt.wavedecn (I1[:, :], wavelet) cooef2 = pywt.wavedecn(I2[:, :], wavelet) # Second: for each level in both image dictobj) # Third: After we fused the cooefficent we nned to transfor back to get the image fusedImage = pywt.waverecn
import pywt import bayes_opt def wavelet_transform(ts): coeffs = pywt.wavedec(ts, 'meyer', level
pip install PyWavelets python版本代码: import pywt import cv2 import numpy as np # This function does the I2 = cv2.imread('VIS1.png', 0) # First: Do wavelet transform on each image wavelet = 'db2' cooef1 = pywt.wavedec2 (I1[:, :], wavelet, level=1) cooef2 = pywt.wavedec2(I2[:, :], wavelet, level=1) # Second: for each level c3)) # Third: After we fused the cooefficent we nned to transfor back to get the image fusedImage = pywt.waverec2
# 小波重构denoised_signal = pywt.waverec(coeffs_thresh, wavelet)整体去噪代码:def wavelet_denoising(signal, wavelet ='db1', level=1, thresholding='soft'): # 小波分解 coeffs = pywt.wavedec(signal, wavelet, level=level calculate_sure_threshold(c) if thresholding == 'hard': coeffs_thresh.append(pywt.threshold sure_threshold, mode='hard')) elif thresholding == 'soft': coeffs_thresh.append(pywt.threshold (c, sure_threshold, mode='soft')) # 小波重构 denoised_signal = pywt.waverec(coeffs_thresh, wavelet
网上找了好多文章都没有提到这个东西,没有说明 wavedec2 函数各个返回值究竟是什么意思 我们先看看 wavedec2 函数的大概形式, pywt.wavedec2(data, wavelet , cD1)] 单单这么看可能不太好懂,所以来个实例,我的目的是把11.xlsx 里面的灰度图像进行3层的小波变换,并要提取变换后的低频分量的系数和高频分量的系数 实例 import pywt xlsx' # 数据路径 x = excel2matrix(pathX) # 我的灰度图数据 w = 'sym4' # 小波基类型 l = 3 # 小波变换层次 coeffs = pywt.wavedec2
import matplotlib.pyplot as plt from matplotlib.pyplot import imshow import numpy as np # 小波库 import pywt (im, (256, 256)) img = cv2.cvtColor(im, cv2.COLOR_BGR2GRAY).astype(np.float32) # 对图像进行小波分解 coeffs = pywt.dwt2 plt.subplot(224), plt.imshow(HH, ‘gray’), plt.title(“HH”) plt.show() 结果如下: 对图像进行小波重构 # 很简单,直接拿轮子来用 img_r = pywt.idwt2
pip install ptwt python版本(cuda加速)代码 import pywt import ptwt import torch import numpy as np import cv2 reconstruction = np.transpose(reconstruction, (1, 2, 0)) return reconstruction python版本(cpu)代码 import pywt cooef def channelTransform(ch1, ch2, ch3, FUSION_METHOD): # wavelet transformation cooef1 = pywt.wavedec2 (ch1, 'haar', level=1) cooef2 = pywt.wavedec2(ch2, 'haar', level=1) cooef3 = pywt.wavedec2(ch3 + cD2 + cD3) / 3 fincoC = cA, (cH, cV, cD) # wavelet iverse transformation outImageC = pywt.waverec2
pip install PyWavelets python版本代码: import pywt import cv2 import numpy as np import math from scipy import I2 = cv2.imread('VIS1.png', 0) # First: Do wavelet transform on each image wavelet = 'db2' cooef1 = pywt.wavedec2 (I1[:, :], wavelet, level=1) cooef2 = pywt.wavedec2(I2[:, :], wavelet, level=1) # Second: for each level c3)) # Third: After we fused the cooefficent we nned to transfor back to get the image fusedImage = pywt.waverec2