我与python3擦肩而过（二）—— csv文件头哪去啦？

　　　　在看Python Data Visualization Cookbook 这本书（基于python2），开始时读取csv文件头的时候出现问题。查了资料，又是python3的问题，从这个链接找到答案。

书中源码是这样的：

 

　　

import csv

filename = 'ch02-data.csv'
data = []
try:
    with open(filename) as f:
        reader = csv.reader(f)
        #注意这里的缩进应该是书的印刷错误
　　 header = reader.next() 
　　 data = [row for row in reader] 
except: 
        ...略...

　　开始在python3运行报错如下：

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

　　查资料发现在python3里面，reader已经没有了next属性。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
        ...

　　上文提到过，这里书的缩进在印刷上可能有问题(header和data语句应该在with语句块里面)。我按照原缩进，在python2和3两种环境下测试的时候，报同样的错如下：

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

　　于是，再次修改代码，python3版本完整代码如下（python2只需要将缩进改正即可，直接用下面的代码亦可）

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)	

　　成功输出结果：

['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']