用另一个 csv 文件中的更新信息更新现有 csv 文件

Question

我有 2 个 csv 文件，

• 文件zulu 包含基本信息，分列。
• 文件bommel 仅更新了相同列中具有相同记录的信息。

我想在没有 Pandas 或其他外部资源的情况下在 Python 中解决这个问题（使用标准库中的 csv 模块）。

#!/usr/bin/env python3
import csv

# Define column names
fields = ['capcode', 'discipline', 'region', 'location', 'description', 'remark']

# Open the neccesary files
with open('bommel_db_capcodes.txt', 'r') as readFile_bommel:
    with open('results.csv', 'w') as results:
            with open('zulu_db_capcodes.txt', 'r') as readFile_zulu:
                master = csv.DictReader(readFile_zulu, fieldnames=fields)
                update = csv.DictReader(readFile_bommel, fieldnames=fields)
                writer = csv.DictWriter(results, fieldnames=fields)

                # Saves and skips header to output file
                writer.writerow(next(master))

                # Goes through whole zulu csv
                for row in master:
                    for row2 in update:
                        if row['capcode'] in update:
                            writer.writerow(row2)
                        else:
                            writer.writerow(row)

ReadFilezulu.close()
ReadFilebommel.close()
results.close()

zulucsv的内容：

capcode,discipline,region,location,description,remark
000400001,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water (Noord)
000400002,Brandweer,Groningen,Groningen,,
000400003,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water) (Oost)
000100000,Brandweer,Amsterdam-Amstelland,Amsterdam-Amstelland,Aalsmeer,Postalarm
000100001,Brandweer,Amsterdam-Amstelland,Amsterdam-Amstelland,,
000100002,Brandweer,Amsterdam-Amstelland,Amsterdam-Amstelland,,Banaanzulu
000100003,Brandweer,Amsterdam-Amstelland,Amsterdam-Amstelland,,

bommelcsv的内容：

capcode,discipline,region,location,description,remark
000100000,Brandweer,Amsterdam-Amstelland,,banaanProefalarm,
000100001,Brandweer,Amsterdam-Amstelland,Aalsmeer,Bevelvoerders,
000100004,Brandweer,Amsterdam-Amstelland,Aalsmeer,Korpsalarm,

当前结果

capcode,discipline,region,location,description,remark
000400001,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water (Noord)
000400001,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water (Noord)
000400001,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water (Noord)

预期结果

capcode,discipline,region,location,description,remark                                            < from saving header
000400001,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water (Noord)     < from zulu
000400002,Brandweer,Groningen,Groningen,,                                                        < from zulu
000400003,Brandweer,Groningen,Groningen,Regionaal,Pelotonscommandant Logistiek/Water) (Oost)     < from zulu
000100000,Brandweer,Amsterdam-Amstelland,,banaanProefalarm,                                      < from bommel
000100001,Brandweer,Amsterdam-Amstelland,Aalsmeer,Bevelvoerders,                                 < from bommel
000100002,Brandweer,Amsterdam-Amstelland,Amsterdam-Amstelland,,Banaanzulu                        < from zulu
000100003,Brandweer,Amsterdam-Amstelland,Amsterdam-Amstelland,,                                  < from zulu
000100004,Brandweer,Amsterdam-Amstelland,Aalsmeer,Korpsalarm,                                    < from bommel

关于如何完成这项工作的任何想法？

Answer 1

当您第一次使用条件in update 时，您会消耗整个输入文件。因为update 基本上是一个生成器，所以当你循环遍历它时会耗尽它。

此外，您的条件检查更新文件中是否存在完全同一行，当然它不存在（如果数据完全相同，您将不希望或不需要更新任何内容)。

您想将更新行读入内存一次，然后当您看到具有相同键的行（不是整行！）时从主文件中跳过这些行（不是整行！）

我假设第一个字段 (capcode) 是这里的关键，但可能还有其他安排。

切线，您可以合并所有with 语句；而当你使用with open 时，就不需要.close() 任何东西了。

#!/usr/bin/env python3
import csv


fields = ['capcode', 'discipline', 'region', 'location', 'description', 'remark']

with open('bommel_db_capcodes.txt', 'r') as readFile_bommel, \
        open('results.csv', 'w') as results, \
        open('zulu_db_capcodes.txt', 'r') as readFile_zulu:

    master = csv.DictReader(readFile_zulu, fieldnames=fields)
    update = csv.DictReader(readFile_bommel, fieldnames=fields)
    writer = csv.DictWriter(results, fieldnames=fields)

    # Save header to output file and skip
    writer.writerow(next(master))

    # Skip header from updates
    next(update)

    # Read, remember, and write updated lines
    seen = set()
    for row in update:
        writer.writerow(row)
        seen.add(row['capcode'])

    for row in master:
        if row['capcode'] not in seen:
            writer.writerow(row)

演示：https://ideone.com/7Aj1PQ