我與python3擦肩而過（二）—— csv文件頭哪去啦？

　　　　在看Python Data Visualization Cookbook 這本書（基於python2），開始時讀取csv文件頭的時候出現問題。查了資料，又是python3的問題，從這個鏈接找到答案。

 

書中源碼是這樣的：

 

　　

import csv

filename = 'ch02-data.csv'
data = []
try:
    with open(filename) as f:
        reader = csv.reader(f)
        #注意這里的縮進應該是書的印刷錯誤
　　 header = reader.next() 
　　 data = [row for row in reader] 
except: 
        ...略...

 

　　開始在python3運行報錯如下：

Traceback (most recent call last):
  File "F:\Techonolgoy\Python\file\blog\csv_open.py", line 8, in <module>
    header = reader.next()
AttributeError: '_csv.reader' object has no attribute 'next'

　　查資料發現在python3里面，reader已經沒有了next屬性。python3中用力如下：

import csv
with open('stocks.csv') as f:
    f_csv = csv.reader(f)
    headers = next(f_csv)
    for row in f_csv:
        # Process row
        ...

　　上文提到過，這里書的縮進在印刷上可能有問題(header和data語句應該在with語句塊里面)。我按照原縮進，在python2和3兩種環境下測試的時候，報同樣的錯如下：

Traceback (most recent call last):
  File "F:\Techonolgoy\Python\file\blog\csv_open.py", line 8, in <module>
    header = next(reader)
ValueError: I/O operation on closed file.

　　於是，再次修改代碼，python3版本完整代碼如下（python2只需要將縮進改正即可，直接用下面的代碼亦可）

import csv

filename = 'ch02-data.csv'
data = []
try:
	with open(filename) as f:
		reader = csv.reader(f)
		header = next(reader)
		data = [row for row in reader]
except csv.Error as e:
	print("Error reading CSV file at line %s: %s"%(reader.line_num, e))

if header:
	print(header)
	print("=====================")
for datarow in data:
	print(datarow)	

　　成功輸出結果：

['day', 'ammount']
=====================
['2013-01-24', '323']
['2013-01-25', '233']
['2013-01-26', '433']
['2013-01-27', '555']
['2013-01-28', '123']
['2013-01-29', '0']
['2013-01-30', '221']