排序和數據字典的名單在Python

Question

結合我有類似這樣一個字典列表：

{'Catch': 4.414, 'ShipID': 173, 'Name': u'Sigur\xf0ur \xd3lafsson SF - 44', 'Gear': u'BOTN'} 
{'Catch': 2.401, 'ShipID': 173, 'Name': u'Sigur\xf0ur \xd3lafsson SF - 44', 'Gear': u'BOTN'} 
{'Catch': 67.463, 'ShipID': 1275, 'Name': u'J\xf3n V\xeddal\xedn VE - 82', 'Gear': u'BOTN'} 
{'Catch': 51.803, 'ShipID': 1275, 'Name': u'J\xf3n V\xeddal\xedn VE - 82', 'Gear': u'BOTN'} 
{'Catch': 7.539, 'ShipID': 1595, 'Name': u'Fr\xe1r VE - 78', 'Gear': u'BOTN'} 
{'Catch': 97.984, 'ShipID': 1903, 'Name': u'\xdeorsteinn \xdeH - 360', 'Gear': u'BOTN'} 
{'Catch': 94.796, 'ShipID': 1903, 'Name': u'\xdeorsteinn \xdeH - 360', 'Gear': u'BOTN'} 
{'Catch': 61.347, 'ShipID': 2020, 'Name': u'Su\xf0urey VE - 12', 'Gear': u'BOTN'} 
{'Catch': 21.135, 'ShipID': 2401, 'Name': u'\xde\xf3runn Sveinsd\xf3ttir VE - 401', 'Gear': u'BOTN'} 
{'Catch': 16.151, 'ShipID': 2444, 'Name': u'Vestmannaey VE - 444', 'Gear': u'BOTN'} 
{'Catch': 41.213, 'ShipID': 2677, 'Name': u'Bergur VE - 44', 'Gear': u'BOTN'} 
{'Catch': 5.046, 'ShipID': 2403, 'Name': u'Hvanney SF - 51', 'Gear': u'NET'} 
{'Catch': 2.311, 'ShipID': 2403, 'Name': u'Hvanney SF - 51', 'Gear': u'NET'} 
{'Catch': 6.304, 'ShipID': 2403, 'Name': u'Hvanney SF - 51', 'Gear': u'NET'} 
{'Catch': 4.231, 'ShipID': 2732, 'Name': u'Skinney SF - 20', 'Gear': u'NET'} 
{'Catch': 6.46, 'ShipID': 2732, 'Name': u'Skinney SF - 20', 'Gear': u'NET'} 
... 

此列表預分揀與此：

list_sorted = sorted(landingList, key=lambda d:(d['Gear'], d['ShipID'])) 

這是在冰島的船隻着陸列表以及我想要做的事情是將清單按「齒輪」分割並添加捕獲物以顯示總捕獲量。這個

的「BOTN名單類似的會是這樣的：

{'Catch': 6.815, 'ShipID': 173, 'Name': u'Sigur\xf0ur \xd3lafsson SF - 44', 'Gear': u'BOTN'} 
{'Catch': 119.266, 'ShipID': 1275, 'Name': u'J\xf3n V\xeddal\xedn VE - 82', 'Gear': u'BOTN'} 
{'Catch': 7.539, 'ShipID': 1595, 'Name': u'Fr\xe1r VE - 78', 'Gear': u'BOTN'} 
{'Catch': 192.78, 'ShipID': 1903, 'Name': u'\xdeorsteinn \xdeH - 360', 'Gear': u'BOTN'} 
{'Catch': 61.347, 'ShipID': 2020, 'Name': u'Su\xf0urey VE - 12', 'Gear': u'BOTN'} 
{'Catch': 21.135, 'ShipID': 2401, 'Name': u'\xde\xf3runn Sveinsd\xf3ttir VE - 401', 'Gear': u'BOTN'} 
{'Catch': 16.151, 'ShipID': 2444, 'Name': u'Vestmannaey VE - 444', 'Gear': u'BOTN'} 
{'Catch': 41.213, 'ShipID': 2677, 'Name': u'Bergur VE - 44', 'Gear': u'BOTN'} 

然後「淨」名單會是這樣的：

{'Catch': 13.661, 'ShipID': 2403, 'Name': u'Hvanney SF - 51', 'Gear': u'NET'} 
{'Catch': 10.691, 'ShipID': 2732, 'Name': u'Skinney SF - 20', 'Gear': u'NET'} 

當然也有更多的齒輪和着陸。但這只是爲了證明清單是如何看待的，以及我手頭的任務。你能幫我解決這個問題嗎？

Answer 1

可以使用itertools.groupby() function：

from itertools import groupby 
from operator import itemgetter 

for gear, group in groupby(list_sorted, key=itemgetter('Gear')): 
    # group is now an iterator, loop over it to get all items with the same value for Gear. 
    # gear is the value of this group's "Gear" key. 

Answer 2

@Martijn指定使用itertools.groupby，但執行不會是直線前進。下面是我如何能夠到位

from itertools import groupby, tee 
from operator import itemgetter 
from copy import deepcopy 
#Create a Wrapper named combine to wrap the entire functionality 
def combine(data): 

    #Which has a nested function to calculate the subtotal 
    #For each Gear and Name Pair 
    def subtotal(data): 
      #Now Iterate through the grouped Gear Items 
     for k1, v1 in data.iteritems(): 
      #And save the current Gear 
      gear = k1 
      #For Each person grouped catch 
      for k2, v2 in v1: 
       #Save the name 
       name = k2 
       #Create two iterator from one 
       #We need this as we don't want 
       #to lose the iterator after we 
       #make an entire pass to calculate 
       #the total catch 
       v2_1, v2_2 = tee(v2) 
       #Now calculate the total catch for each person 
       tot_catch = sum(e['Catch'] for e in v2_1) 
       #and select the first element from the group 
       v2_2 = next(v2_2) 
       #and update the catch with the total catch under 
       #his belt and discard the rest 
       v2_2['Catch'] = catch 
       #finlly yield a tuple of the subtotal row 
       #along with the gear and fisherman's name 
       yield (gear, name, v2_2) 
    #First create a copy of the data as we would be changing it in-place 
    data = deepcopy(data) 
    #First Group by the Gear 
    data_groupby_Gear = groupby(data, key = itemgetter('Gear')) 
    #For each Gear group by the fisherman 
    data_groupby_Gear_then_Name = {k: groupby(list(v), itemgetter('Name')) 
            for k,v in data_groupby_Gear} 
    #and return the combined result 
    return subtotal(data_groupby_Gear_then_Name) 

#Just iterate through the combined data and print 
#in any way you desire 
for gear, name, sumtotal in combine(data): 
    print u"{:10} {:20} {}".format(gear, name, sumtotal) 

以及最終輸出看起來像下面得到這個，但可根據需要

NET  Hvanney SF - 51  {'Catch': 13.661000000000001, 'ShipID': 2403, 'Name': u'Hvanney SF - 51', 'Gear': u'NET'} 
NET  Skinney SF - 20  {'Catch': 10.690999999999999, 'ShipID': 2732, 'Name': u'Skinney SF - 20', 'Gear': u'NET'} 
BOTN  Sigurður Ólafsson SF - 44 {'Catch': 6.8149999999999995, 'ShipID': 173, 'Name': u'Sigur\xf0ur \xd3lafsson SF - 44', 'Gear': u'BOTN'} 
BOTN  Jón Vídalín VE - 82 {'Catch': 119.26599999999999, 'ShipID': 1275, 'Name': u'J\xf3n V\xeddal\xedn VE - 82', 'Gear': u'BOTN'} 
BOTN  Frár VE - 78   {'Catch': 7.539, 'ShipID': 1595, 'Name': u'Fr\xe1r VE - 78', 'Gear': u'BOTN'} 
BOTN  Þorsteinn ÞH - 360 {'Catch': 192.78, 'ShipID': 1903, 'Name': u'\xdeorsteinn \xdeH - 360', 'Gear': u'BOTN'} 
BOTN  Suðurey VE - 12  {'Catch': 61.347, 'ShipID': 2020, 'Name': u'Su\xf0urey VE - 12', 'Gear': u'BOTN'} 
BOTN  Þórunn Sveinsdóttir VE - 401 {'Catch': 21.135, 'ShipID': 2401, 'Name': u'\xde\xf3runn Sveinsd\xf3ttir VE - 401', 'Gear': u'BOTN'} 
BOTN  Vestmannaey VE - 444 {'Catch': 16.151, 'ShipID': 2444, 'Name': u'Vestmannaey VE - 444', 'Gear': u'BOTN'} 
BOTN  Bergur VE - 44  {'Catch': 41.213, 'ShipID': 2677, 'Name': u'Bergur VE - 44', 'Gear': u'BOTN'}