Python3-笔记-E-011-库-CSV

import csv, pprint

def ReadFile2List():
    file = open('example.csv')
    reader = csv.reader(file)
    data = list(reader)
    pprint.pprint(data)
    print(data[0][2]) # 可以用下标
    print(data[6][1])
    '''
[['4/5/2015 13:34', 'Apples', '73'],
 ['4/5/2015 3:41', 'Cherries', '85'],
 ['4/6/2015 12:46', 'Pears', '14'],
 ['4/8/2015 8:59', 'Oranges', '52'],
 ['4/10/2015 2:07', 'Apples', '152'],
 ['4/10/2015 18:10', 'Bananas', '23'],
 ['4/10/2015 2:40', 'Strawberries', '98']]
73
Strawberries
    '''

# Reader 对象只能循环遍历一次。要再次读取 CSV 文件，必须调用csv.reader，创建一个对象。
def ReadFileIter():
    reader = csv.reader(open('example.csv'))
    for row in reader:
        print('row #' + str(reader.line_num) + ' ' + str(row))
        print(row[1]) # row是个list可以用下标
'''
row #1 ['4/5/2015 13:34', 'Apples', '73']
Apples
row #2 ['4/5/2015 3:41', 'Cherries', '85']
Cherries
row #3 ['4/6/2015 12:46', 'Pears', '14']
Pears
row #4 ['4/8/2015 8:59', 'Oranges', '52']
Oranges
row #5 ['4/10/2015 2:07', 'Apples', '152']
Apples
row #6 ['4/10/2015 18:10', 'Bananas', '23']
Bananas
row #7 ['4/10/2015 2:40', 'Strawberries', '98']
Strawberries
'''


# 按行写入
def Write2CSV():
    file = open('output.csv', 'w', newline='')
    writer = csv.writer(file)
    print('写入了字符和数:%d' % writer.writerow(['4/5/2015 13:34', 'Apples']))
    writer.writerow(['4/10/2015 2:40', 'Strawberries', '98'])
    writer.writerow(['4/6/2015 12:46'])
    file.close()
'''
4/5/2015 13:34,Apples
4/10/2015 2:40,Strawberries,98
4/6/2015 12:46

'''
# 改变分隔符与换行符
def Write2CSV2():
    csvFile = open('example.tsv', 'w', newline='')
    # 分割使用制表符，换行为两行
    csvWriter = csv.writer(csvFile, delimiter='	', lineterminator='

')
    csvWriter.writerow(['apples', 'oranges', 'grapes'])
    csvWriter.writerow(['eggs', 'bacon', 'ham'])
    csvWriter.writerow(['spam', 'spam', 'spam', 'spam', 'spam', 'spam'])
    csvFile.close()
'''
apples oranges    grapes

eggs   bacon  ham

spam   spam   spam   spam   spam   spam

'''

# 遍历当前目录内的csv去除第一行，然后在此写入到子目录的同名文件中
import csv, os
dirname = 'headerRemoved'
os.makedirs(dirname, exist_ok=True)
for file in os.listdir('.'):
    if file.endswith('.csv'):
        print('remove header from ' + file + '......')
        srcfile = open(file)
        reader = csv.reader(srcfile)
        data = list(reader)
        srcfile.close()

        dstfile = open(os.path.join(dirname, file), 'w', newline='')
        writer = csv.writer(dstfile)
        dstdata = data[1:]
        for line in dstdata:
            writer.writerow(line)
        dstfile.close()