2014-01-25 54 views
0

我有一个停靠公共交通站点的字典。我想复制那些正在传输的文件(有多个行),以便每个附加行都有一个停止复制停止。我最初将这些副本存储在一个名为duplicates的字典中。但是,在将相应行的名称分配给每个复制停止位后,它们都会被原始停止位的原始行列表中的最后一行覆盖。所以我最终得到了一堆重复的站点,所有站点都有相同的线路,而不是每个线路一站。什么是压倒这些价值?文件l_stops.csv在Dropboxbpaste上。为什么在此循环结束时字典值被覆盖?

import csv 
import random 

def stop_coords(): 
    with open('l_stops.csv', 'rb') as csvfile: 
     stop_reader = csv.reader(csvfile, delimiter=',', quotechar='"') 
     stops = {} 
     for row in stop_reader: 
      map_id = row[5] 
      lines = set() 
      if row[7] == 'true': 
       lines.add('Red') 
      if row[8] == 'true': 
       lines.add('Blue') 
      if row[9] == 'true': 
       lines.add('Green') 
      if row[10] == 'true': 
       lines.add('Brown') 
      if row[11] == 'true': 
       lines.add('Purple') 
      if row[13] == 'true': 
       lines.add('Yellow') 
      if row[14] == 'true': 
       lines.add('Pink') 
      if row[15] == 'true': 
       lines.add('Orange') 
      if map_id not in stops: 
       stop_name = row[2].partition('(')[0].rstrip(' ') 
       lat = float(row[16].lstrip('"(').rpartition(',')[0]) 
       lng = float(row[16].lstrip('"(').rpartition(',')[2].strip(')"')) 
       stop = {} 
       stop['name'] = stop_name 
       stop['lat'] = lat 
       stop['lng'] = lng 
       stop['x'] = lng 
       stop['y'] = lat 
       stop['lines'] = lines 
       stops[map_id] = stop 
       stop['duplicateStops'] = [] 
      elif stops[map_id]['lines'] != lines: 
       stops[map_id]['lines'] = stops[map_id]['lines'].union(lines) 
     for item in stops: 
      stops[item]['lines'] = list(stops[item]['lines']) 

     # Add duplicate stops for stops that are transfers (shared by multiple lines) 
     duplicates = {} # the dictionary that will hold the duplicates and be added to the stops dictionary after all duplicate stops have been processed 
     for item in stops: 
      num_lines = len(stops[item]['lines']) 
      if num_lines > 1: # if a stop has more than one line 
       original_lines = stops[item]['lines'] 
       stops[item]['lines'] = original_lines[0] 
       equivalent_map_ids = [item] # Make a list of different map_ids that represent the same stop (but on different lines). The first map_id in the list will be the "original" one. 
       for i in range(num_lines - 1): # for each line after the first one 
        # Create a new map_id and make sure it doesn't conflict with an existing map_id 
        while True: 
         new_map_id = str(random.randint(10000, 99999)) 
         if new_map_id not in stops and new_map_id not in duplicates: 
          break 
        duplicates[new_map_id] = stops[item] # duplicate the stop 
        equivalent_map_ids.append(new_map_id) # add the new map_id to the list of equivalent map_ids 
       # Set the duplicateStops value of everyone in equivalent_map_ids's to the other stops' map_ids 
       # The first map_id in equivalent_map_ids is the original one that's in the stops dictionary, so set its duplicateStops value to the rest of the list 
       stops[item]['duplicateStops'] = equivalent_map_ids[1:] 

       # For the rest of the map_ids in equivalent_map_ids 
       j = 1 
       for duplicate_stop in stops[item]['duplicateStops']: 
        duplicates[duplicate_stop]['lines'] = original_lines[j] 
        duplicates[duplicate_stop]['duplicateStops'] = equivalent_map_ids[:j] + equivalent_map_ids[(j + 1):] # this line also changes stops[item]['duplicateStops'], not sure how 
        j+= 1 
       # somehow by this point all duplicates have the same line (the last line in the original 'lines' list) 
       for stop in stops[item]['duplicateStops']: 
        print duplicates[stop]['name'] 
        print duplicates[stop]['lines'] 

     for item in duplicates: 
      print item 
      print duplicates[item]['name'] 
      print duplicates[item]['lines'] 
     stops.update(duplicates) 
     stops['none'] = {'name' : 'none', 'lat' : 0, 'lng' : 0, 'x' : 0, 'y' : 0, 'lines' : ['none']} 

调试时,我发现,重新分配重复[duplicate_stop] [ 'duplicateStops']也重新分配停止[项目] [ 'duplicateStops']。这怎么可能?重复和停止是两个单独的词典。

回答

2

然后duplicates[duplicate_stop]stops[item]相同对象 - 和变异对象,那么,改变对象。对象是而不是自动复制/克隆/复制在作业上或作为函数参数使用时。

问题的行是最有可能

duplicates[new_map_id] = stops[item] # duplicate the stop 

..和评论是错误因为不发生重复。


问题Understanding dict.copy() - shallow or deep?可能会有用;至少它展示了如何制作一个真正的副本。