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:\Techonolgoy\Python\file\blog\csv_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:\Techonolgoy\Python\file\blog\csv_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']
