csv format
csv comma seperated values
like a spreadsheet with no formulas
easy to process with code
python中的csv
在python中，csv文件通常呈现为一个由行组成的列表
1.each row is a list
the overall data structure is a list of lists
csv=[['A1','A2','A3'],
['B1','B2','B3']]
2.csv文件有标题行
each row is a dictionary
the keys of each dictionary can be column names and the fields can be values
the overall data structure is a list of dictionary
csv=[{'name1':'A1','name2':'A2','name3':'A3'},
{'name1':'B1','name2':'B2','name3':'B3'}]
unicode读取csv
import unicodecsv
enrollments=[]
f=open('enrollments.csv')
reader = unicodecsv.DictReader(f) #reader 并不是行列表，而是迭代器，可用迭代器编写获取各元素的循环，但这是一次性的
for row in reader :
enrollments.append(row)
for row in reader: #如果用第二个循环打印出reader中的所有行，那么输出结果为空，因为对每个迭代器只能进行一次循环
print row
f.close()
enrollments[0]
优化版：
import unicodecsv
with open('enrollments.csv','rb') as f: #使用with语句避免最后还要关闭文件
reader = unicodecsv.DictReader(f)
enrollments = list(reader) #将迭代器转化为列表
enrollments[0]
读取
enrollments.csv
daily_engagement.csv
project_submissions.csv
三个文件的数据,并打印第一行
import unicodecsv
def read_csv(filename):
with open(filename,'rb') as f:
reader = unicodecsv.DictReader(f)
return list(reader)
enrollments = read_csv('enrollments.csv')
daily_engagement = read_csv('daily-engagement.csv')
project_submissions = read_csv('project-submissions.csv')
print enrollments[0]
print daily_engagement[0]
print project_submissions[0]
