python - 将 csv.DictReader 对象转换为字典列表？

Question

一个csv文件names.csv有内容:

first_name last_name
Baked Beans
Lovely Spam
Wonderful Spam

我想将它读入字典列表，第一行包含键:

>>> import csv
>>> with open('names.csv') as csvfile:
...     reader = csv.DictReader(csvfile)
...     for row in reader:
...         print(row['first_name'], row['last_name'])
...
Baked Beans
Lovely Spam
Wonderful Spam

但是reader是csv.DictReader的类型吗？如何将 reader 转换为字典列表？谢谢。

Answer 1

import csv
with open("in.csv") as csvfile:
    reader = csv.DictReader(csvfile,delimiter=" ")
    print(list(reader))
[{'first_name': 'Baked', 'last_name': 'Beans'}, {'first_name': 'Lovely', 'last_name': 'Spam'}, {'first_name': 'Wonderful', 'last_name': 'Spam'}]

如果分隔符实际上不是 ， 则需要指定 "" 或其他任何内容。

为了消除混淆，代码在 python3.6 上也可以正常工作，唯一的区别是使用 DictReader给 Orderdicts默认情况下:

In [1]: import csv
   ...: with open("in.csv") as csvfile:
   ...:     reader = csv.DictReader(csvfile, delimiter=" ")
   ...:     print(list(reader))
   ...:     
[OrderedDict([('first_name', 'Baked'), ('last_name', 'Beans')]), OrderedDict([('first_name', 'Lovely'), ('last_name', 'Spam')]), OrderedDict([('first_name', 'Wonderful'), ('last_name', 'Spam')])]

您可以完全一样地访问 key ，OrderedDict 只是保持 key 插入顺序:

In [2]: import csv
   ...: with open("in.csv") as csvfile:
   ...:     reader = csv.DictReader(csvfile, delimiter=" ")
   ...:     for dct in reader:
   ...:         print(f"{dct['first_name']} {dct['last_name']}")
   ...:         
   ...:     
Baked Beans
Lovely Spam
Wonderful Spam

py3.6 实际上也是如此，所以如果出于某种原因你真的想要一个 dict:

In [5]: import csv
   ...: with open("in.csv") as csvfile:
   ...:     reader = csv.DictReader(csvfile, delimiter=" ")
   ...:     for dct in map(dict, reader):
   ...:         print(dct)
   ...:         print(f"{dct['first_name']} {dct['last_name']}")
   ...:         
   ...:     
{'first_name': 'Baked', 'last_name': 'Beans'}
Baked Beans
{'first_name': 'Lovely', 'last_name': 'Spam'}
Lovely Spam
{'first_name': 'Wonderful', 'last_name': 'Spam'}
Wonderful Spam

py3.6 中插入时的排序保留是一个实现细节，可能会发生变化，但如果我们有足够多的人使用它，它可能只需要保留 :)