如何使用csv.writer

Question

添加自定義的專欄中，我有一個python腳本，需要一個巨大的文件，並複製出只，我想同時，也寫在新文件中新的自定義標題中的幾列。

import csv,time,string,os, requests 

og_file = "\\\\network\\x\\test.csv" 
today = time.strftime("%Y-%m-%d") 


#fields to keep from original file 
fields = ["As Of Date", "Ph", "Home Country"] 

with open(og_file) as infile, open("c:\\upload\\output_" + today + ".csv", "wb") as outfile: 
    r = csv.DictReader(infile) 
    w = csv.DictWriter(outfile, fields, extrasaction="ignore") 

    wtr = csv.writer(outfile)  
    wtr.writerow(["upload_date", "phone", "country"]) 
    for row in r: 
     w.writerow(row) 

在我寫這個文件，我需要與多家每一行的開頭創建一個額外的列，從1開始，並持續至ñ，因此輸出看起來是這樣的：

id | upload_date | phone | country 
1  2012-01-01   555-1234  USA 
2  2012-02-01   555-1235  USA 
3  2012-03-01   555-1236  USA 
4  2012-04-01   555-1237  USA 

我不知道我會怎麼做。

Answer 1

fields = ["id"] + fields # so it'll write later 

with open(og_file) as infile, open("c:\\upload\\output_" + today + ".csv", "wb") as outfile: 
    r = csv.DictReader(infile) 
    w = csv.DictWriter(outfile, fields, extrasaction="ignore") 

    wtr = csv.writer(outfile)  
    wtr.writerow(["id","upload_date", "phone", "country"]) 
    for i,row in enumerate(r, start=1): 
     row["id"] = i 
     w.writerow(row) 

Answer 2

可以使用itertools.count對象爲id列：

from itertools import count 

with open(og_file) as infile, open("c:\\upload\\output_" + today + ".csv", "wb") as outfile: 
    r = csv.DictReader(infile) 
    w = csv.DictWriter(outfile, fields, extrasaction="ignore") 

    wtr = csv.writer(outfile)  
    wtr.writerow(["id", "upload_date", "phone", "country"]) 
    c = count(1) 
    for row in r: 
     row['id'] = next(c) 
     w.writerow(row)