python CSV模块使用笔记

import csv

csv.reader:

reader(csvfile[, dialect=’excel’][, fmtparam])

reader = csv.reader(file('glucoseData.csv', 'rb'))
for line in reader:
print line

>>['l490', 'l660', 'l730', 'l850', 'l930', 'glucose', 'glucose_level']
['0.221', '0.329', '0.323', '0.443', '0.355', '8.1', '3']
['0.21', '0.328', '0.322', '0.438', '0.371', '7.6', '3']
['0.203', '0.318', '0.309', '0.387', '0.371', '7.4', '3']
['0.2', '0.289', '0.3', '0.367', '0.297', '5.9', '2']

csv.writer

writer(csvfile[, dialect=’excel’][, fmtparam])

writer = csv.writer(file('your.csv', 'wb'))
writer.writerow(['Column1', 'Column2', 'Column3'])
lines = [range(3) for i in range(5)]
for line in lines:
writer.writerow(line)

DictWriter

可以把json格式的字典保存成csv

rows = [{'Column1': '0', 'Column2': '1', 'Column3': '2', 'Column4': '3'},
{'Column1': '0', 'Column2': '1', 'Column3': '2', 'Column4': '3'},
{'Column1': '0', 'Column2': '1', 'Column3': '2', 'Column4': '3'},
{'Column1': '0', 'Column2': '1', 'Column3': '2', 'Column4': '3'},
{'Column1': '0', 'Column2': '1', 'Column3': '2', 'Column4': '3'}]

＃ 这样就可以直接调用DictWriter.writerows方法来处理了:

import csv

fieldnames = ['Column1', 'Column2', 'Column3', 'Column4']
dict_writer = csv.DictWriter(file('your.csv', 'wb'), fieldnames=fieldnames)
dict_writer.writerow(fieldnames) # CSV第一行需要自己加入
dict_writer.writerows(rows)  # rows就是表单提交的数据

结合with open as 使用

确保文件使用后关闭

with open(file('glucoseData.csv', 'rb')) as csvFile:

reader = csv.reader(csvFile)
for line in reader:
print line