假设你所有的键都是唯一的......那么这个（稍微修改）：

project_index = [
{'A': ['1', '2', '3']},
{'B': ['4', '5', '6']},
{'C': ['7', '8', '9']},
{'D': ['10', '11', '12', '20']},
{'E': ['13', '14', '15']},
{'F': ['16', '17', '18']}
]

应该看起来像这样：

project_index_dict = {}
for x in project_index:
    project_index_dict.update(x)

print(project_index_dict)
# Output:
 
{'A': ['1', '2', '3'],
 'B': ['4', '5', '6'],
 'C': ['7', '8', '9'],
 'D': ['10', '11', '12', '20'],
 'E': ['13', '14', '15'],
 'F': ['16', '17', '18']}

在这一点上，与其重新发明轮子......不如使用pandas。

import pandas as pd

# Work-around for uneven lengths:
df = pd.DataFrame.from_dict(project_index_dict, 'index').T.fillna('')
df.to_csv('file.csv', index=False)

输出file.csv：

A,B,C,D,E,F
1,4,7,10,13,16
2,5,8,11,14,17
3,6,9,12,15,18
,,,20,,

csv模块方法：

import csv
from itertools import zip_longest, chain

header = []
for d in project_index:
    header.extend(list(d))

project_index_rows = [dict(zip(header, x)) for x in 
                      zip_longest(*chain(list(*p.values()) 
                                         for p in project_index), 
                                  fillvalue='')]

with open('file.csv', 'w') as f:
    writer = csv.DictWriter(f, fieldnames = header)
    writer.writeheader()
    writer.writerows(project_index_rows)

我的解决方案不使用Pandas。计划如下：

• 对于标题行，从字典中获取所有键
• 对于数据行，使用zip转置列-〉行

import csv

def first_key(d):
    """Return the first key in a dictionary."""
    return next(iter(d))

def first_value(d):
    """Return the first value in a dictionary."""
    return next(iter(d.values()))
    
with open("output.csv", "w", encoding="utf-8") as stream:
    writer = csv.writer(stream)

    # Write the header row
    writer.writerow(first_key(d) for d in project_index)

    # Write the rest
    rows = zip(*[first_value(d) for d in project_index])
    writer.writerows(rows)

输出.csv的内容：

A,B,C,D,D,F
1,4,7,10,13,16
2,5,8,11,14,17
3,6,9,12,15,18