问题描述
import csv
for line in open('candidates.csv'):
csv_row = line.strip().split(',')
check_update(csv_row[7]) #check_update is a function that returns an int
如何在我正在读取的行(行)的末尾附加check_updates函数返回的数据? 这是我尝试过的:
for line in open('candidates.csv'):
csv_row = line.strip().split(',')
data_to_add = check_update(csv_row[7])
with open('candidates.csv','a') as f:
writer = csv.writer(f)
writer.writerow(data_to_add)
出现此错误:
_csv.Error: iterable expected,not nonetype
也不完全确定该添加到我正在阅读的行的末尾的正确位置。
底线,如何最好地在当前正在读取的行末添加数据?
解决方法
请备份文件,以防万一。
您可以编写一个新的临时文件,并将其移至您读取的旧文件上。
from tempfile import NamedTemporaryFile
import shutil
import csv
filename = 'candidates.csv'
tempfile = NamedTemporaryFile('w',delete=False)
with open(filename,'r',newline='') as csvFile,tempfile:
writer = csv.writer(tempfile)
for line in csvFile:
csv_row = line.strip().split(',')
csv_row.append(check_update(csv_row[7])) # this will add the data to the end of the list.
writer.writerow(csv_row)
shutil.move(tempfile.name,filename)