python 处理 DictReader 缺少键

Question

这个脚本工作正常，直到我点击一个空的单元格:

import csv,time,string,os,requests
dw = "\\\\network\\folder\\btc.csv"

inv_fields = ["id", "rsl", "number", "GP%"]

with open(dw) as infile, open("c:\\upload\\log.csv", "wb") as outfile:
    r = csv.DictReader(infile)
    w = csv.DictWriter(outfile, inv_fields, extrasaction="ignore")
    r = (dict((k, v.strip()) for k, v in row.items() if v) for row in r)

    wtr = csv.writer( outfile )    
    wtr.writerow(["id", "resale", "number", "percentage"])
    for i, row in enumerate(r, start=1):
        row['id'] = i
        row['GP%'] = row['GP%'].replace("%","")
        w.writerow(row)

print "file successfully saved"

脚本在这一行失败:

row['GP%'] = row['GP%'].replace("%","")

通过将 print i 添加到循环中，我可以看到它在 .csv 文件的该输入值为空的行上失败。如何将没有值(value)的单元格带入这个方程？

Python 错误:

Traceback (most recent call last):
  File "backlog.py", line 80, in <module>
    row['GP%'] = row['GP%'].replace("%","")
KeyError: 'GP%'

Answer 1

在尝试更新其值之前，您可以检查键 'GP%' 是否在 row 字典中。如果不是，您可以分配一个默认值，以便与该 id 相关的条目在输出文件中为空:

for i, row in enumerate(r, start=1):
    row['id'] = i
    if 'GP%' in row:
         row['GP%'] = row['GP%'].replace('%','')
    else:
         row['GP%'] = ''
    w.writerow(row)

或者使用row的get方法设置默认值:

for i, row in enumerate(r, start=1):
    row['id'] = i
    row['GP%'] = row.get('GP%', '').replace('%','')
    w.writerow(row)