的Python：添加列基於第一欄和第二欄

Question

我有重複的值CSV文件中的第一列，例如一個CSV文件：

mg,known,127 
mg,unknown,142 
pnt,known,37 
pnt,unknown,0 
lmo,known,75 
lmo,unknown,3 
sl,known,197 
sl,unknown,21 
oc,unknown,32 
oc,known,163 
sv,known,368 
sv,unknown,308 
az,unknown,6 
az,known,241 
bug,unknown,1 
bug,known,167 
li,unknown,15 
li,known,174 
lg,known,3 

我想要做的是建立一個新的csv文件，使得例如：

header1, known, unknown 
mg, 127, 142 
pnt, 37, 0 

我試圖找出如何我才能真正構建該行：

def read_stats(path): 
    has_seen = set() 
    with open(writepath, 'wb') as write_csv: 
     with open(path, 'r') as csv_file: 
      data_reader = csv.reader(csv_file, delimiter=',') 
      for line in data_reader: 
       if line[0] in has_seen: 

這是我目前遇到的位置，是否必須保留指向下一行的指針？

Answer 1

這裏有一個辦法，聚集在一個OrderedDict結果：

>>> import csv 
>>> import collections 

>>> d = collections.OrderedDict() 
>>> for header1, category, value in csv.reader(datafile): 
     d.setdefault(header1, {})[category] = value 

>>> for header1, m in d.items(): 
     print ', '.join([header1, m['known'], m['unknown']]) 

mg, 127, 142 
pnt, 37, 0 
lmo, 75, 3 
sl, 197, 21 
oc, 163, 32 
sv, 368, 308 
az, 241, 6 
bug, 167, 1 
li, 174, 15 

如果您可以假設總是在連續對與已知組第一線，您可以創建的已知，中間結果和發射完整排行爲：

>>> for header1, category, value in csv.reader(data): 
     if category == 'known': 
      result = [header1, value] 
     else: 
      result += [value] 
      print ', '.join(result) 

mg, 127, 142 
pnt, 37, 0 
lmo, 75, 3 
sl, 197, 21 
oc, 163, 32 
sv, 368, 308 
az, 241, 6 
bug, 167, 1 
li, 174, 15