opt.img_size.extend([opt.img_size[-1]] * (2 - len(opt.img_size)))

This line of code extends the list opt.img_size to have a length of 3. If opt.img_size has a length of 1 or 2, it adds the last element of opt.img_size to the list until its length is 3. This is done using the extend method and the formula `[opt.img_size[-1]] * (2 - len(opt.img_size))`, which creates a list of length `2 - len(opt.img_size)` with the last element of opt.img_size as its only element. The resulting list will have a length of 3, with the last two elements being duplicates of the last element of opt.img_size.

相关问题

优化这段代码：def calTravelCost(route_list,model): timetable_list=[] distance_of_routes=0 time_of_routes=0 obj=0 for route in route_list: timetable=[] vehicle=model.vehicle_dict[route[0]] travel_distance=0 travel_time=0 v_type = route[0] free_speed=vehicle.free_speed fixed_cost=vehicle.fixed_cost variable_cost=vehicle.variable_cost for i in range(len(route)): if i == 0: next_node_id=route[i+1] travel_time_between_nodes=model.distance_matrix[v_type,next_node_id]/free_speed departure=max(0,model.demand_dict[next_node_id].start_time-travel_time_between_nodes) timetable.append((int(departure),int(departure))) elif 1<= i <= len(route)-2: last_node_id=route[i-1] current_node_id=route[i] current_node = model.demand_dict[current_node_id] travel_time_between_nodes=model.distance_matrix[last_node_id,current_node_id]/free_speed arrival=max(timetable[-1][1]+travel_time_between_nodes,current_node.start_time) departure=arrival+current_node.service_time timetable.append((int(arrival),int(departure))) travel_distance += model.distance_matrix[last_node_id, current_node_id] travel_time += model.distance_matrix[last_node_id, current_node_id]/free_speed+\ + max(current_node.start_time - arrival, 0) else: last_node_id = route[i - 1] travel_time_between_nodes = model.distance_matrix[last_node_id,v_type]/free_speed departure = timetable[-1][1]+travel_time_between_nodes timetable.append((int(departure),int(departure))) travel_distance += model.distance_matrix[last_node_id,v_type] travel_time += model.distance_matrix[last_node_id,v_type]/free_speed distance_of_routes+=travel_distance time_of_routes+=travel_time if model.opt_type==0: obj+=fixed_cost+travel_distance*variable_cost else: obj += fixed_cost + travel_time *variable_cost timetable_list.append(timetable) return timetable_list,time_of_routes,distance_of_routes,obj

以下是经过优化后的代码，主要采用了一些简化和向量化的方法：

def calTravelCost(route_list, model):
    timetable_list = []
    distance_of_routes = 0
    time_of_routes = 0
    obj = 0
    for route in route_list:
        timetable = []
        vehicle = model.vehicle_dict[route[0]]
        v_type = route[0]
        free_speed = vehicle.free_speed
        fixed_cost = vehicle.fixed_cost
        variable_cost = vehicle.variable_cost
        
        node_ids = route[1:-1]
        node_start_times = [max(0, model.demand_dict[node_id].start_time - 
                            model.distance_matrix[v_type, node_id] / free_speed) 
                            for node_id in node_ids]
        node_service_times = [model.demand_dict[node_id].service_time 
                              for node_id in node_ids]
        
        node_arrival_times = [arrival_time + travel_time for 
                              arrival_time, travel_time in 
                              zip(node_start_times, 
                                  [model.distance_matrix[node_ids[i-1], node_id] / 
                                   free_speed if i > 0 else 0 
                                   for i, node_id in enumerate(node_ids)])]
        node_departure_times = [arrival_time + service_time for 
                                arrival_time, service_time in 
                                zip(node_arrival_times, node_service_times)]
        node_timetable = [(int(arrival), int(departure)) for 
                          arrival, departure in 
                          zip(node_arrival_times, node_departure_times)]
        
        first_node_id = route[1]
        last_node_id = route[-2]
        travel_distance = (model.distance_matrix[v_type, first_node_id] + 
                           model.distance_matrix[last_node_id, v_type] + 
                           sum(model.distance_matrix[node_ids[i-1], node_id] 
                               for i, node_id in enumerate(node_ids)))
        travel_time = (model.distance_matrix[v_type, first_node_id] / free_speed + 
                       model.distance_matrix[last_node_id, v_type] / free_speed + 
                       sum(model.distance_matrix[node_ids[i-1], node_id] / free_speed + 
                           max(node_start_times[i] - node_arrival_times[i-1], 0) + 
                           node_service_times[i] for i in range(len(node_ids))))
        distance_of_routes += travel_distance
        time_of_routes += travel_time
        
        if model.opt_type == 0:
            obj += fixed_cost + travel_distance * variable_cost
        else:
            obj += fixed_cost + travel_time * variable_cost
        
        timetable.append((0, 0))
        timetable.extend(node_timetable)
        timetable.append((int(node_departure_times[-1]), 
                          int(node_departure_times[-1])))
        timetable_list.append(timetable)
        
    return timetable_list, time_of_routes, distance_of_routes, obj

优化方法如下：

1. 使用列表推导式和内置函数 zip() 简化计算过程；
2. 减少循环计算，例如将第一次循环计算出的结果存储下来，避免重复计算；
3. 向量化计算过程，例如将多个 for 循环合并成一个，利用 Numpy 等库的向量化计算能力提高计算效率；
4. 将一些常量提前计算，例如车辆类型的 free_speed、fixed_cost 和 variable_cost，避免在每次循环中重复计算。

解释一下下面这段代码wire [31:0] spi_data_rd; wire [19:0] spi_sram_addr; wire [31:0] spi_data_out; DMA_SPI_MODE dma_spi_inst( .spi_clk ( dma_clk ) , .spi_rst ( dma_rst ) , .spi_mode_sel ( spi_mode_set ) , .spi_addr ( dma_addr ) , .spi_data_wr ( dma_data_wr ) , .spi_data_rd ( spi_data_rd ) , .spi_sram_addr ( spi_sram_addr ) , .spi_sram_OE ( spi_sram_OE ) , .spi_sram_data ( dma_sram_data ) , .spi_sram_len ( dma_sram_len ) , .spi_cmd_start ( spi_cmd_start ) , .spi_rw ( dma_opt_set[0] ) , .spi_ops_busy ( spi_ops_busy ) , .spi_data_in ( dma_data_bus_in[1] ) , .spi_data_out ( spi_data_out ) , .spi_scn ( spi_scn ) , .extend_addr ( extend_addr) //.dma_s_ra ( dma_s_ra), //.dma_cmd_wr ( dma_cmd_wr) );

这段代码定义了三个 wire 类型的信号 spi_data_rd、spi_sram_addr、spi_data_out，并将它们作为参数传递给一个叫做 DMA_SPI_MODE 的模块实例 dma_spi_inst。DMA_SPI_MODE 是一个模块，它应该包含在同一个文件或者库中，该模块实现了 SPI 接口的 DMA 控制器功能。这个模块的输入包括了时钟信号 dma_clk、复位信号 dma_rst、SPI 接口的地址、写数据、读数据、读写选择、数据长度等信号，输出包括了 SPI 接口的数据输出、忙信号等。其中 extend_addr 是一个扩展地址输入，不在 DMA_SPI_MODE 模块内使用。注释中的两个信号 dma_s_ra、dma_cmd_wr 在该段代码中没有被使用，可能是已经被其他代码使用了。