如何在一定条件下选择矩阵的元素？

python# 示例矩阵
matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

# 条件：选择所有大于5的元素
selected_elements = [element for row in matrix for element in row if element > 5]

print(selected_elements)  # 输出: [6, 7, 8, 9]

pythonimport numpy as np

# 示例矩阵
matrix = np.array([
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
])

# 条件：选择所有大于5的元素
selected_elements = matrix[matrix > 5]

print(selected_elements)  # 输出: [6 7 8 9]

# 如果需要获取满足条件的元素的索引
indices = np.where(matrix > 5)
print(indices)  # 输出: (array([1, 2, 2, 2]), array([2, 0, 1, 2]))

pythonimport numpy as np

# 示例矩阵
matrix = np.array([
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
])

# 创建布尔数组
bool_array = matrix > 5

# 使用布尔数组选择元素
selected_elements = matrix[bool_array]

print(selected_elements)  # 输出: [6 7 8 9]

# 选择满足条件的行
selected_rows = matrix[bool_array.any(axis=1)]

print(selected_rows)
# 输出:
# [[4 5 6]
#  [7 8 9]]

python# 示例矩阵
matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

# 条件：选择所有大于5的元素
selected_elements = []
for row in matrix:
    for element in row:
        if element > 5:
            selected_elements.append(element)

print(selected_elements)  # 输出: [6, 7, 8, 9]

pythonimport numpy as np

# 示例矩阵
matrix = np.array([
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
])

# 选择第二行中大于4的元素
selected = matrix[1][matrix[1] > 4]

print(selected)  # 输出: [5 6]

pythonimport numpy as np

# 示例矩阵
matrix = np.array([
    [1, 6, 3],
    [4, 7, 8],
    [7, 2, 9]
])

# 条件：大于5且小于9
condition = (matrix > 5) & (matrix < 9)

# 替换满足条件的元素为0
matrix[condition] = 0

print(matrix)
# 输出:
# [[1 0 3]
#  [4 0 0]
#  [0 2 9]]