使用Python Dictionary在Python中合并CSV文件

Posted 2021-03-27

您好我正在尝试根据公共列或主键合并两个CSV文件中的特定字段来创建新的CSV文件。我尝试在powershell中做同样的事情并且它工作但是在完成这个过程非常慢 - 超过30分钟合并5000+行文件所以在Python中尝试这个。我是新人，所以请放轻松我。

因此，两个文件是infile.csv和checkfile.csv，创建的输出文件中的列将基于infile.csv中的列。代码检查checkfile.csv中的值，创建outfile.csv，从infile.csv复制列，并需要根据checkfile.com中的相应值重写两个字段的值。以下是详细信息

infile.csv -

"StockNumber","SKU","ChannelProfileID","CostPrice"
"10m_s-vid#APTIIAMZ","2VV-10",3746,0.33
"10m_s-vid#CSE","2VV-10",3746,0.98
"1RR-01#CSE","1RR-01",3746
"1RR-01#PCAWS","1RR-01",3746,
"1m_s-vid_ext#APTIIAMZ","2VV-101",3746,0.42

checkfile.csv

ProductCode, Description, Supplier, CostPrice, RRPPrice, Stock, Manufacturer, SupplierProductCode, ManuCode, LeadTime
2VV-03,3MTR BLACK SVHS M - M GOLD CABLE - B/Q 100,Cables Direct Ltd,0.43,,930,CDL,2VV-03,2VV-03,1
2VV-05,5MTR BLACK SVHS M - M GOLD CABLE - B/Q 100,Cables Direct Ltd,0.54,,1935,CDL,2VV-05,2VV-05,1
2VV-10,10MTR BLACK SVHS M - M GOLD CABLE - B/Q 50,Cables Direct Ltd,0.86,,1991,CDL,2VV-10,2VV-10,1

我得到的outfile.csv是 -

StockNumber,SKU,ChannelProfileID,CostPrice
10m_s-vid#APTIIAMZ,2VV-10,"(' ',)", 
10m_s-vid#CSE,2VV-10,"(' ',)", 
1RR-01#CSE,1RR-01,"(' ',)", 
1RR-01#PCAWS,1RR-01,"(' ',)", 
1m_s-vid_ext#APTIIAMZ,2VV-101,"(' ',)", 

但我需要的outfile.csv是 -

StockNumber,SKU,ChannelProfileID,CostPrice
10m_s-vid#APTIIAMZ,2VV-10,1991,0.86  
10m_s-vid#CSE,2VV-10,1991,0.86   
1RR-01#CSE,1RR-01
1RR-01#PCAWS,1RR-01          
1m_s-vid_ext#APTIIAMZ,2VV-101

最后的代码 -

import csv

with open('checkfile.csv', 'rb') as checkfile:
    checkreader = csv.DictReader(checkfile)

    product_result = dict(
        ((v['ProductCode'], v[' Stock']), (v['ProductCode'], v[' CostPrice']))  for v in checkreader
    )

with open('infile.csv', 'rb') as infile:
    with open('outfile.csv', 'wb') as outfile:
        reader = csv.DictReader(infile)

        writer = csv.DictWriter(outfile, reader.fieldnames)
        writer.writeheader()

        for item in reader:
            result = product_result.get(item['SKU'], " ")

            item['ChannelProfileID'] = result,
            item['CostPrice'] = result

            writer.writerow(item)

答案

你可以让它变得更简单：

import csv

with open('checkfile.csv', 'rb') as checkfile:
    product_result = {
        record['ProductCode']: record for record in csv.DictReader(checkfile)}

with open('infile.csv', 'rb') as infile:
    with open('outfile.csv', 'wb') as outfile:
        reader = csv.DictReader(infile)
        writer = csv.DictWriter(outfile, reader.fieldnames)
        writer.writeheader()
        for item in reader:
            record = product_result.get(item['SKU'], None)
            if record:
                item['ChannelProfileID'] = record[' Stock']  # ???
                item['CostPrice'] = record[' CostPrice']
            else:
                item['ChannelProfileID'] = None
                item['CostPrice'] = None
            writer.writerow(item)

我不确定我用???评论过的那一行。

此外，如果您确实想要生成损坏的CSV，请随意省略else子句。

我用StringIO对象测试了它。它生成了您指定的结果，但是使用尾随逗号，其中checkfile中没有匹配项。

我使用Python 2.7 dict理解，因为你用python-2.7标记了你的问题。

另一答案

import csv

product_result = {}

with open('checkfile.csv', 'rb') as checkfile:
    checkreader = csv.DictReader(checkfile)

    for v in checkreader:
        product_result[v['ProductCode']] = (v[' Stock'], v[' CostPrice'])

with open('infile.csv', 'rb') as infile:
    with open('outfile.csv', 'wb') as outfile:
        reader = csv.DictReader(infile)
        writer = csv.DictWriter(outfile, reader.fieldnames)
        writer.writeheader()

        for item in reader:
            result = product_result.get(item['SKU'])
            if result:
               item['ChannelProfileID'], item['CostPrice'] = result
            else:
               item['ChannelProfileID'] = item['CostPrice'] = None

            writer.writerow(item)

另一答案

import re
import csv
import collections
import glob

# Variables

total_record = []
headerCount = 0

for file in glob.glob("*.csv"):
    print(file)

    with open(file, 'r') as f:
        reader = csv.reader(f)
        list_record = list(reader)
        if headerCount == 0:
            headerCount = 1
            total_record.extend(list_record)
        else:
            list_record.pop(0)
            total_record.extend(list_record)

with open('combine.csv', 'w') as csvFile:
    writer = csv.writer(csvFile)
    writer.writerows(total_record)