python每日一練之I/O實現讀寫csv文件

CSV：以純文本形式存儲數據，由任意數目的記錄組成，記錄之間以某種字符分隔

1.寫文件

def write_csv():
    list1 = [[1, 2, 3], [4, 5, 6]]
    header = [0, 0, 0]
    l2 = [7, 8, 9]
    # utf-8-sig 此種格式能夠用excel打開；newline若是不寫明，每次write後，會自動增長新行。
    with open('csv3.csv', 'w', encoding='utf-8-sig', newline='') as f:
        writer = csv.writer(f)
        writer.writerow(header)  # 寫入一行
        writer.writerows(list1)
        writer.writerow(l2)

2.讀取文件

若是不加編碼格式，這裏會報錯：'gbk' codec can't decode byte 0xbf in position 2: illegal multibyte sequence 能夠聲明忽略編碼錯誤：errors='ignore'的，可是讀出來的數據會有亂碼。

def read_csv():
    with open('csv3.csv', 'r', encoding='utf-8-sig') as f:
        reader = csv.reader(f)
        header = next(reader)  # 獲取行頭
        print(header)
        for r1 in reader:
            print(r1)

3.寫入字典

def write_dict():
    header = ['name', 'sex']
    dict1 = {'name': "test", 'sex': 18}

    with open('csv4.csv', 'w', encoding='utf-8-sig', newline='') as f:
        writer = csv.DictWriter(f, header)  # 須要標題,若是沒有會報錯__init__() missing 1 required positional argument: 'fieldnames'
        writer.writeheader()
        writer.writerow(dict1)  # 能夠寫入單行或者多行 rows

4. 讀取字典

def read_dict():
    with open('csv4.csv', 'r', encoding='utf-8-sig') as f:
        reader = csv.DictReader(f)
        # 無需讀取標題
        for row in reader:  # 每次讀取一行，返回一個dict
            print(row['name'], row['sex'])