%改良圈 Len=size(A,1); if index_start < index_end c=[index_start 1:index_start-1 index_start+1:index_end-1 index_end+1:Len index_end]; else c=[index_start 1:index_end-1 index_end+1:index_start-1 index_start+1:Len index_end]; end此部分代码作用是什么,为什么要这样做
时间: 2024-04-22 15:25:45 浏览: 38
这部分代码是用于对图像进行改良圈排序的。改良圈排序是一种贪心算法,它通过交换相邻的图像来最小化它们之间的差异。
首先,代码计算了数组"A"的大小,并根据起始和结束图像的索引确定了数组"c"的初始值。
这里有一个条件判断语句,它检查起始索引是否小于结束索引。如果是,那么"c"数组的顺序是按照起始索引、1到起始索引之前的索引、起始索引之后到结束索引之前的索引、结束索引之后到数组长度的索引,最后是结束索引。如果不是,那么"c"数组的顺序是按照起始索引、1到结束索引之前的索引、结束索引之后到起始索引之前的索引、起始索引之后到数组长度的索引,最后是结束索引。
这样做的目的是为了将相邻图像之间的差异最小化。通过交换相邻的图像,可以使得相邻图像之间的差异更小,从而得到更好的图像排序效果。
最后,代码使用改良圈排序对"c"数组进行了迭代,并通过交换相邻的元素来优化图像排序。
这样做可以使得相邻图像之间具有更高的相似性,从而在拼接图像时得到更连续、更平滑的效果。
相关问题
分析class MemoryManager: def __init__(self, allocator): self.allocator = allocator self.process_list = [] def allocate(self, process, request_size): block_start = -1 end = -1 memory_view = self.allocator.memory_view() i = 0 while i < 256: if memory_view[i] == None: if end < 0: end = i if (memory_view[i] is not None) and (end >= 0): move_lenght = i - end k = memory_view[i] for j in self.process_list: if j == k: a = j.get_memory() j_start = a[0] self.allocator.free_memory(j) length_area = j.block j_start = j_start - move_lenght self.allocator.allocate_memory(j_start, length_area, j) memory_view = self.allocator.memory_view() i = -1 break end = -1 i = i + 1 memory_view = self.allocator.memory_view() for j in range(len(memory_view)): # 0~255 if memory_view[j] == None: if block_start < 0: block_start = j if (memory_view[j] is not None) and (block_start >= 0): if j - block_start == request_size: break elif j - block_start < request_size: block_start = -1 self.process_list.append(process) self.allocator.allocate_memory(block_start, request_size, process)
这是一个内存管理器MemoryManager的类定义,它有一个构造函数__init__和一个分配内存的函数allocate。构造函数接受一个分配器(allocator)作为输入参数,并将其存储在实例变量self.allocator中。而process_list是一个存储进程的列表,初始为空。allocate函数接受一个进程process和请求的内存大小request_size作为输入参数,然后通过访问分配器的memory_view方法来获取内存的使用情况,并根据情况进行内存分配。如果找到了合适的块,则将进程添加到process_list中,并通过访问分配器的allocate_memory方法分配内存。如果没有找到合适的块,则将block_start设置为-1。
使用首次适应算法改写class MemoryManager: def __init__(self, allocator): self.allocator = allocator def allocate(self, process, request_size): memory_view = self.allocator.memory_view() '''这里是写的''' # Find the best fit block for the process best_fit_block = None best_fit_size = float('inf') for i in range(len(memory_view)): if memory_view[i] is None: # Check if the block is free block_size = 0 j = i while j < len(memory_view) and memory_view[j] is None: block_size += 1 j += 1 if block_size >= request_size and block_size < best_fit_size: best_fit_block = i best_fit_size = block_size if best_fit_block is not None: # Allocate memory for the process block_start = best_fit_block self.allocator.allocate_memory(block_start, request_size, process) else: # No suitable block found, allocation failed raise AssertionError('allocation failed')
可以将首次适应算法改写成以下代码:
```
class MemoryManager:
def __init__(self, allocator):
self.allocator = allocator
self.last_allocated = 0
def allocate(self, process, request_size):
memory_view = self.allocator.memory_view()
# Find the best fit block for the process
best_fit_block = None
best_fit_size = float('inf')
i = self.last_allocated
while i < len(memory_view):
if memory_view[i] is None: # Check if the block is free
block_size = 0
j = i
while j < len(memory_view) and memory_view[j] is None:
block_size += 1
j += 1
if block_size >= request_size and block_size < best_fit_size:
best_fit_block = i
best_fit_size = block_size
i += 1
# If no block is found from last allocated position to end then search from beginning
if best_fit_block is None:
i = 0
while i < self.last_allocated:
if memory_view[i] is None: # Check if the block is free
block_size = 0
j = i
while j < len(memory_view) and memory_view[j] is None:
block_size += 1
j += 1
if block_size >= request_size and block_size < best_fit_size:
best_fit_block = i
best_fit_size = block_size
i += 1
if best_fit_block is not None:
# Allocate memory for the process
block_start = best_fit_block
self.allocator.allocate_memory(block_start, request_size, process)
self.last_allocated = block_start + request_size
else:
# No suitable block found, allocation failed
raise AssertionError('allocation failed')
```
这里的改动在于在 `allocate` 方法中加入了 `self.last_allocated` 变量,它表示上一次分配内存时的位置,从这个位置开始向后搜索空闲块,避免在整个内存中搜索。如果在搜索到结尾仍然没有找到适合的块,则从头开始搜索。
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