Question

csv文件names.csv包含内容：

first_name last_name
Baked Beans
Lovely Spam
Wonderful Spam

我想把它读成一个字典列表，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reader csv.DictReader的类型是什么？如何将reader转换为词典列表？感谢。

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。

为了清除任何混淆，代码也适用于python3.6，唯一的区别是使用DictReader默认情况下会Orderdicts：

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')])]

您可以完全相同地访问密钥，OrderedDict只保留密钥插入顺序：

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

其中py3.6实际上也是如此，所以如果由于某种原因你真的想要一个字典：

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

在py3.6中插入时的订购保留是一个实现细节并且可能会发生变化，但如果我们有足够的人使用它，它可能只需要保留：）

Answer 2

使用list()：

print(list(reader))

演示：

>>> with open('names.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'}]

Answer 3

创建功能

import csv


def csv_to_dict(filename):
    result_list=[]
    with open(filename) as file_obj:
        reader = csv.DictReader(file_obj, delimiter=delimiter)
        for row in reader:
            result_list.append(dict(row))
    return result_list

并使用它：

list_of_dicts = csv_to_dict('names.csv')

Answer 4

csv.DictReader创建一个dictreader对象，如标题中所述。该对象仅在文件打开且无法切片时可用。

根据标题将对象转换为列表。...

list_of_dicts = list(your_dictreader_object)

将csv.DictReader对象转换为字典列表？

4 个答案: