Python 批量更改txt文件中的第一列数值

把2改为16，把1改为15。也就是第一列的内容进行修改替换，其他不变。

b = []
with open('text.txt', 'r',encoding='utf8') as f:
    print(f)
    while True:
        _ = f.readline()
        print(_)

        if _:
            b.append(_.split(' '))
        else:
            break

    for i in range(len(b)):
        print(b[i])
        if b[i][0] == '2':
            b[i][0] = '16'
        elif b[i][0] == '1':
            b[i][0] = '15'
with open('text.txt', 'w+', encoding='utf8') as f:
    for i in b:
        f.writelines(' '.join(i))