python csv模块

import csv  # Comma Separated Value

# class Dialect
#     delimiter = None           # 分隔符
#     doublequote = None         # 元素是引用符，双倍的引用符。默认是true，如果改为false就需要设置分隔符，否则报错。
#     escapechar = None          # 转义符
#     lineterminator = None      # 行终止符
#     quotechar = None           # 引用符
#     quoting = None             # 引用方式
#     skipinitialspace = None    # 忽略分割后面的空格，默认是flase
#
#
# QUOTE_ALL = 1         # 全加引号
# QUOTE_MINIMAL = 0     # 分隔符和引用符号加双引号
# QUOTE_NONE = 3        # 全部不加双引号，分隔符要加转义符
# QUOTE_NONNUMERIC = 2  # 数字不加引号
#
# csv.QUOTE_MINIMAL means only when required, for example, when a field contains either the quotechar or the delimiter
# csv.QUOTE_ALL means that quotes are always placed around fields.
# csv.QUOTE_NONNUMERIC means that quotes are always placed around fields which do not parse as integers or floating point numbers.
# csv.QUOTE_NONE means that quotes are never placed around fields.


# 1、写一个csv文件  quoting=csv.QUOTE_ALL
with open("1.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f, dialect="excel", quoting=csv.QUOTE_ALL)
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"', 6])

with open("1.csv", "rb") as f:
    print(f.read())
    # b'"A","B",",","5"
"E","F","""","6"
'

with open("1.csv", "r") as f:
    print(f.read())
    # "A","B",",","5"
    # "E

# 2、写一个csv文件  quoting=csv.QUOTE_MINIMAL
with open("2.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f, dialect="excel", quoting=csv.QUOTE_MINIMAL)
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"', 6])

with open("2.csv", "rb") as f:
    print(f.read())
    # b'A,B,",",5
E,F,"""",6
'

with open("2.csv", "r") as f:
    print(f.read())
    # A,B,",",5
    # E,F,"""",6


# 3、写一个csv文件  quoting=csv.QUOTE_NONE
with open("3.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f, dialect="excel", quoting=csv.QUOTE_NONE, escapechar='\')  # 这种方式需要设置转义符
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"', 6])

with open("3.csv", "rb") as f:
    print(f.read())
    # b'A,B,\,,5
E,F,\",6
'

with open("3.csv", "r") as f:
    print(f.read())
    # A,B,\,,5
    # E,F,",6


# 4、写一个csv文件  quoting=csv.QUOTE_NONNUMERIC
with open("4.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f, dialect="excel", quoting=csv.QUOTE_NONNUMERIC)
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"', 6])

with open("4.csv", "rb") as f:
    print(f.read())
    # b'"A","B",",",5
"E","F","""",6
'

with open("4.csv", "r") as f:
    print(f.read())
    # "A","B",",",5
    # "E","F","""",6


# 5、写一个csv文件  quoting=默认 (quoting=csv.QUOTE_MINIMAL)
with open("5.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f, dialect="excel")
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"', 6])

with open("5.csv", "rb") as f:
    print(f.read())
    # b'A,B,",",5
E,F,"""",6
'

with open("5.csv", "r") as f:
    print(f.read())
    # A,B,",",5
    # E,F,"""",6


# 6、写一个csv文件
with open("6.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f)
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"', 6])

with open("6.csv", "rb") as f:
    print(f.read())
    # b'A,B,",",5
E,F,"""",6
'

with open("6.csv", "r") as f:
    print(f.read())
    # A,B,",",5
    # E,F,"""",6


# 7、注册风格
csv.register_dialect('mystyle', delimiter=',', quoting=csv.QUOTE_MINIMAL)
with open("7.csv", "w", newline="") as f:
    # dialect为打开csv文件的方式，默认是excel，delimiter="	"参数指写入的时候的分隔符
    # csv_writer = csv.writer(f, dialect="excel-tab")
    # csv_writer = csv.writer(f, dialect="excel", delimiter="	")
    csv_writer = csv.writer(f, dialect="mystyle")
    # csv文件插入一行数据，把下面列表中的每一项放入一个单元格（可以用循环插入多行）
    csv_writer.writerow(["A", "B", ",", 5])
    csv_writer.writerow(["E", "F", '"""', 6])

with open("7.csv", "rb") as f:
    print(f.read())
    # b'A,B,",",5
E,F,"""""""",6
'

with open("7.csv", "r") as f:
    print(f.read())
    # A,B,",",5
    # E,F,"""""""",6


# 8、读取csv文件
csv.register_dialect('mystyle', delimiter=',', quoting=csv.QUOTE_MINIMAL)
with open('7.csv', newline='') as f:
    reader = csv.reader(f, 'mystyle')
    for r in reader:
        print(r, type(r))
        # ['A', 'B', ',', '5'] <class 'list'>
        # ['E', 'F', '"', '6'] <class 'list'>


# 9、读取csv文件
for row in csv.reader(['one, two, three', 'one, two, three'], skipinitialspace=True):  # skipinitialspace忽略空格
    print(row, type(row))
    # ['one', 'two', 'three'] <class 'list'>
    # ['one', 'two', 'three'] <class 'list'>


# 10、DictWriter
with open('8.csv', 'w', newline='') as csv_file:
    fieldnames = ['first_name', 'last_name']
    writer = csv.DictWriter(csv_file, fieldnames=fieldnames)

    writer.writeheader()
    writer.writerow({'first_name': 'Baked', 'last_name': 'Beans'})
    writer.writerow({'first_name': 'Lovely', 'last_name': 'Spam'})
    writer.writerow({'first_name': 'Wonderful', 'last_name': 'Spam'})
    writer.writerows([{'first_name': 'Wonderful', 'last_name': 'Spam'}, {'first_name': 'Wonderful', 'last_name': 'Spam'}])

# 11、DictReader
with open('8.csv', newline='') as csv_file:
    reader = csv.DictReader(csv_file)
    for row in reader:
        print(row)  # OrderedDict([('first_name', 'Baked'), ('last_name', 'Beans')])
        print(row['first_name'], row['last_name'])