字典列表中的值-Python 3

Question

我想提取一個字典值列表，以便可以將它們寫入csv。

我試圖使用上一個SO問題中的信息來復制所有鍵值。

In [41]: dicts = [
    ...: {"name": "Tom", "age": 10},
    ...: {"name": "Mark", "age": 5},
    ...: {"name": "Pam", "age": 7},
    ...: {"name": "Dick", "age": 12},
    ...: ]

但是我得到的輸出非常復雜，有時是字典，有時是值。

In [25]: for item in dicts:
    ...:     for k, v in item.items():
    ...:         print("Key: {0} and Value: {1}".format(k,v))
    ...:
    ...:
Key: name and Value: {'name': 'Dick', 'age': 12, 0: {...}}
Key: age and Value: 10
Key: 0 and Value: {'name': 'Dick', 'age': 12, 0: {...}}
Key: name and Value: Mark
Key: age and Value: 5
Key: name and Value: Pam
Key: age and Value: 7
Key: name and Value: Dick
Key: age and Value: 12
Key: 0 and Value: {'name': 'Dick', 'age': 12, 0: {...}}

我希望輸出中沒有字典，所有鍵和值都不會提取。 我看到有更好的方法可以做到這一點，但是錯誤是由於錯誤地粘貼到ipython中。

編輯的更新的Dicts和更新的Dicts的更新輸出確實按預期方式工作。

In [49]: for item in dicts:
    ...:     for k, v in item.items():
    ...:         print("Key: {0} and Value: {1}".format(k,v))
    ...:
Key: name and Value: Tom
Key: age and Value: 10
Key: name and Value: Mark
Key: age and Value: 5
Key: name and Value: Pam
Key: age and Value: 7
Key: name and Value: Dick
Key: age and Value: 12

Answer 1

為什么不只列舉列表並提取值：

for i, entry in enumerate(dicts):
...             print entry['name']," ",entry['age']

然后可以將值寫入csv文件

with open('dict.csv', 'wb') as csv_file:
...         writer = csv.writer(csv_file)
...         for i, entry in enumerate(dicts):
...             writer.writerow([entry['name'],entry['age']])

Answer 2

您可以重新構建字典以滿足您的需求：

dicts = [{'key': k, 'value': v} for item in dicts for k,v in item.items()]

for item in dicts:
    print("Key: {key} and Value: {value}".format(**item))

但是，要將它們直接寫入csv，有一種更好的方法：

import csv

dicts = [{'key': k, 'value': v} for item in dicts for k,v in item.items()]

with open('dicts.csv', 'wb') as f:
    dict_writer = csv.DictWriter(f, dicts[0].keys())
    dict_writer.writeheader()
    dict_writer.writerows(dicts)

Answer 3

您可以將相同鍵字典的列表轉換為具有相同鍵的字典，並且值是原始順序的原始值的列表：

dicts = [
    {"name": "Tom", "age": 10},
    {"name": "Pam", "age": 7},
    {"name": "Dick", "age": 12},
]

dictoflists = {k: [d[k] for d in dicts] for k in dicts[0].keys()}