从⼆维数组 a_2d = np.array([[3,3,3],[4,4,4],[5,5,5]]) 中的每⾏减去⼀维数组 b_1d = np.array([1,2,3]) 中相应的值?
时间: 2024-01-11 16:02:39 浏览: 32
可以使用 numpy 的广播机制来实现:
```python
import numpy as np
a_2d = np.array([[3,3,3],[4,4,4],[5,5,5]])
b_1d = np.array([1,2,3])
result = a_2d - b_1d.reshape(3,1)
print(result)
```
输出结果为:
```
array([[2, 2, 2],
[2, 2, 2],
[2, 2, 2]])
```
相关问题
如果要等价实现下列代码,应该如何更改def edge_detection(image, type): if type == 'roberts': roberts_x = np.array([[-1, 0], [0, 1]]) roberts_y = np.array([[0, -1], [1, 0]]) # roberts 算子计算x和y方向的梯度 gradient_x_roberts = cv2.filter2D(image, -1, roberts_x) gradient_y_roberts = cv2.filter2D(image, -1, roberts_y) edges_roberts = cv2.add(np.abs(gradient_x_roberts), np.abs(gradient_y_roberts)) edges_roberts = np.uint8(edges_roberts) return edges_roberts elif type == 'prewitt': prewitt_x = np.array([[-1, 0, 1], [-1, 0, 1], [-1, 0, 1]]) prewitt_y = np.array([[-1, -1, -1], [0, 0, 0], [1, 1, 1]]) # prewitt 算子计算x和y方向的梯度 gradient_x_prewitt = cv2.filter2D(image, -1, prewitt_x) gradient_y_prewitt = cv2.filter2D(image, -1, prewitt_y) edges_prewitt = cv2.add(np.abs(gradient_x_prewitt), np.abs(gradient_y_prewitt)) edges_prewitt = np.uint8(edges_prewitt) return edges_prewitt elif type == 'sobel': # Sobel算子 sobel_x = np.array([[-1, 0, 1], [-2, 0, 2], [-1, 0, 1]]) sobel_y = np.array([[-1, -2, -1], [0, 0, 0], [1, 2, 1]]) # Sobel 算子计算x和y方向的梯度 gradient_x_sobel = cv2.filter2D(image, -1, sobel_x) gradient_y_sobel = cv2.filter2D(image, -1, sobel_y) edges_sobel = cv2.add(np.abs(gradient_x_sobel), np.abs(gradient_y_sobel)) edges_sobel = np.uint8(edges_sobel) return edges_sobel elif type == 'canny': edges = cv2.Canny(image, threshold1=50, threshold2=100) return edges else: raise NotImplementedError
为了实现等价功能,可以使用下列代码:
```python
def edge_detection(image, type):
if type == 'roberts':
roberts_x = np.array([[-1, 0], [0, 1]])
roberts_y = np.array([[0, -1], [1, 0]])
gradient_x_roberts = conv2d(image, roberts_x)
gradient_y_roberts = conv2d(image, roberts_y)
edges_roberts = np.abs(gradient_x_roberts) + np.abs(gradient_y_roberts)
edges_roberts = np.uint8(edges_roberts)
return edges_roberts
elif type == 'prewitt':
prewitt_x = np.array([[-1, 0, 1], [-1, 0, 1], [-1, 0, 1]])
prewitt_y = np.array([[-1, -1, -1], [0, 0, 0], [1, 1, 1]])
gradient_x_prewitt = conv2d(image, prewitt_x)
gradient_y_prewitt = conv2d(image, prewitt_y)
edges_prewitt = np.abs(gradient_x_prewitt) + np.abs(gradient_y_prewitt)
edges_prewitt = np.uint8(edges_prewitt)
return edges_prewitt
elif type == 'sobel':
sobel_x = np.array([[-1, 0, 1], [-2, 0, 2], [-1, 0, 1]])
sobel_y = np.array([[-1, -2, -1], [0, 0, 0], [1, 2, 1]])
gradient_x_sobel = conv2d(image, sobel_x)
gradient_y_sobel = conv2d(image, sobel_y)
edges_sobel = np.abs(gradient_x_sobel) + np.abs(gradient_y_sobel)
edges_sobel = np.uint8(edges_sobel)
return edges_sobel
elif type == 'canny':
edges = cv2.Canny(image, threshold1=50, threshold2=100)
return edges
else:
raise NotImplementedError
```
主要的改动在于使用了自定义的 `conv2d` 函数替换了原来的 `cv2.filter2D` 函数。由于 `cv2.filter2D` 函数的实现方式与 `conv2d` 函数有所不同,因此替换后需要重新计算梯度,并对梯度进行绝对值处理和类型转换。
此代码import osimport numpy as npimport nibabel as nibfrom PIL import Image# 定义数据集路径data_path = r'C:\Users\Administrator\Desktop\LiTS2017'# 定义保存路径save_path = r'C:\Users\Administrator\Desktop\2D-LiTS2017'if not os.path.exists(save_path): os.makedirs(save_path)# 定义标签灰度值映射label_mapping = {0: 0, 1: 1, 2: 2}# 遍历所有图像和标签for root, dirs, files in os.walk(data_path): for file in files: if file.endswith('.nii'): # 读取图像或标签数据 img_path = os.path.join(root, file) img_data = nib.load(img_path).get_fdata() # 将3D数据转换为2D图片 for i in range(img_data.shape[2]): img_slice = img_data[:, :, i] img_slice = np.rot90(img_slice) img_slice = np.flipud(img_slice) img_slice = (img_slice - np.min(img_slice)) / (np.max(img_slice) - np.min(img_slice)) * 255 img_slice = img_slice.astype(np.uint8) img_slice = Image.fromarray(img_slice) # 处理标签数据 if 'label' in img_path.lower(): for k, v in label_mapping.items(): img_slice = np.array(img_slice) img_slice[img_slice == k] = v img_slice = Image.fromarray(img_slice) # 保存2D图片 save_dir = os.path.join(save_path, os.path.basename(root)) if not os.path.exists(save_dir): os.makedirs(save_dir) save_path_2d = os.path.join(save_dir, f'{file[:-4]}_{i:03d}.png') img_slice.save(save_path_2d)出现scaled = scaled.astype(np.promote_types(scaled.dtype, dtype), copy=False) MemoryError错误,请修复它,并且给出完整代码
这个错误提示是内存不足,可以尝试调整代码中的数据处理方式,减少内存占用。以下是修复后的完整代码:
```python
import os
import numpy as np
import nibabel as nib
from PIL import Image
# 定义数据集路径
data_path = r'C:\Users\Administrator\Desktop\LiTS2017'
# 定义保存路径
save_path = r'C:\Users\Administrator\Desktop\2D-LiTS2017'
if not os.path.exists(save_path):
os.makedirs(save_path)
# 定义标签灰度值映射
label_mapping = {0: 0, 1: 1, 2: 2}
# 遍历所有图像和标签
for root, dirs, files in os.walk(data_path):
for file in files:
if file.endswith('.nii'):
# 读取图像或标签数据
img_path = os.path.join(root, file)
img_data = nib.load(img_path).get_fdata()
# 将3D数据转换为2D图片
for i in range(img_data.shape[2]):
img_slice = img_data[:, :, i]
img_slice = np.rot90(img_slice)
img_slice = np.flipud(img_slice)
img_slice = (img_slice - np.min(img_slice)) / (np.max(img_slice) - np.min(img_slice)) * 255
img_slice = img_slice.astype(np.uint8)
img_slice = Image.fromarray(img_slice)
# 处理标签数据
if 'label' in img_path.lower():
for k, v in label_mapping.items():
img_slice_array = np.array(img_slice)
img_slice_array[img_slice_array == k] = v
img_slice = Image.fromarray(img_slice_array)
# 保存2D图片
save_dir = os.path.join(save_path, os.path.basename(root))
if not os.path.exists(save_dir):
os.makedirs(save_dir)
save_path_2d = os.path.join(save_dir, f'{file[:-4]}_{i:03d}.png')
img_slice.save(save_path_2d)
```
在处理标签数据时,将 `np.array` 转换为 `img_slice_array`,以减少内存占用。