在python中根據條件（計數器和累加器）的字典列表創建列表

Question

我有一個物品清單字典：

ListDictItem = [ {'Item No': 1,'Weight':610,'Quantity':2},{'Item No': 2,'Weight':610,'Quantity':2},{'Item No': 3,'Weight':500,'Quantity':2},{'Item No': 4,'Weight':484,'Quantity':2},{'Item No': 5,'Weight':470,'Quantity':2},{'Item No': 6,'Weight':440,'Quantity':2},{'Item No': 7,'Weight':440,'Quantity':2},{'Item No': 8,'Weight':400,'Quantity':2}] 

我從上面創建了一個權重列表，如下所示：

ItemWeigths: [610.0, 610.0, 500.0, 484.0, 470.0, 440.0,440, 400.0] 

我想將這些物品包裝在架子上，以使每個架子的總重量小於特定值，並具有以下格式的列表：

shelves = [[{'Item No': 1,'Weight':610,'Quantity':2}],[{'Item No': 2,'Weight':610,'Quantity':2}],[{'Item No': 3,'Weight':500,'Quantity':2}],[{'Item No': 4,'Weight':484,'Quantity':2}], [{'Item No': 7,'Weight':440,'Quantity':2}],[{'Item No': 8,'Weight':400,'Quantity':2}] ]

其中特定架子的所有重量的總和<= 610

我創建了一個代碼，該代碼可以正確包裝第一個架子，但是我無法編寫用於創建其他物品的架子的代碼：

shelves=[] 
ShelvesWeightTotal = 0
shelf=[] 
new=[] 
ShelfToPack=[] 

 for i in range(0,len(ItemWeigths)): 
    while ShelvesWeightTotal + ItemWeigths[i]   <= WeightOfObject: 
      shelves += [ItemWeigths[i]] 
      ShelvesWeightTotal = sum(shelves)

上面的代碼適用於第一個項目，但是為了為其余項目創建其他貨架，我編寫了不起作用的代碼：

for i in range(0,len(ItemWeigths)):
    while ItemsToCut !=[]:
        if ShelvesWeightTotal + ItemWeigths[i]   <=WeightOfObject: 
           shelves += [ItemWeigths[i]] 
           ShelvesWeightTotal = sum(shelves)
        ItemWeigths.pop(i)
        ItemsToCut.pop(i)
shelf.append(shelves)

任何建議編寫代碼以更好的方式創建架子的建議將不勝感激。

Answer 1

我采用了一種更簡單的方法：

ListDictItem = [{'Item No': 1,'Weight':610,'Quantity':2},
                {'Item No': 2,'Weight':610,'Quantity':2},
                {'Item No': 3,'Weight':500,'Quantity':2},
                {'Item No': 4,'Weight':484,'Quantity':2},
                {'Item No': 5,'Weight':470,'Quantity':2},
                {'Item No': 6,'Weight':440,'Quantity':2},
                {'Item No': 7,'Weight':440,'Quantity':2},
                {'Item No': 8,'Weight':400,'Quantity':2}]

maxWeight = 610
shelves = []
shelf = []
current_shelf_weight = 0

for item in ListDictItem:
    if current_shelf_weight + item['Weight'] <= maxWeight:
        shelf.append(item)
        current_shelf_weight += item['Weight']
    else:
        shelves.append(shelf)
        if item['Weight'] <= maxWeight:
            shelf = [item]
            current_shelf_weight = item['Weight']
        else:
            shelf = []
            current_shelf_weight = 0

if shelf: #append any remaining items
    shelves.append(shelf)

print("shelves = " + str(shelves))

當我檢查此代碼的輸出時，得到以下信息：

shelves = [[{'Weight': 610, 'Item No': 1, 'Quantity': 2}], [{'Weight': 610, 'Item No': 2, 'Quantity': 2}], [{'Weight': 500, 'Item No': 3, 'Quantity': 2}], [{'Weight': 484, 'Item No': 4, 'Quantity': 2}], [{'Weight': 470, 'Item No': 5, 'Quantity': 2}], [{'Weight': 440, 'Item No': 6, 'Quantity': 2}], [{'Weight': 440, 'Item No': 7, 'Quantity': 2}], [{'Weight': 400, 'Item No': 8, 'Quantity': 2}]]

正是您想要的。

Answer 2

ListDictItem = [ {'Item No': 1,'Weight':610,'Quantity':2},{'Item No': 2,'Weight':610,'Quantity':2},{'Item No': 3,'Weight':500,'Quantity':2},{'Item No': 4,'Weight':484,'Quantity':2},{'Item No': 5,'Weight':470,'Quantity':2},{'Item No': 6,'Weight':440,'Quantity':2},{'Item No': 7,'Weight':440,'Quantity':2},{'Item No': 8,'Weight':400,'Quantity':2}];

sh = []; #weight, itemNo
for a in ListDictItem:
    for b in range(0, a['Quantity']):
        for j in range(0, len(sh)):
            if sh[j]['weight'] + a['Weight'] <= 610:
                sh[j]['weight'] += a['Weight']
                sh[j]['items'].append(a['Item No'])
    else:
        sh.append({'weight' : a['Weight'], 'items' : [a['Item No']]})
print(sh)

一個非常簡單的解決方案。