4.28 每日小三练

1：将列表内的元素,根据位数合并成字典
lst = [1,2,4,8,16,32,64,128,256,512,1024,32769,65536,4294967296] 
 
# 输出 
{ 
    1:[1,2,3,8], 
    2:[16,32,64], 
    3:[128,256,512], 
    4:[1024,], 
    5:[32769,65536], 
    6:[4294967296] 
}   每次输出的数，位数加一

list = [1,2,4,8,16,32,64,128,256,512,1024,32769,65536,4294967296]
dic = {}
for i in list:
    if len(i) in dic:
        dic[len(str(i))].append(i)
    else:
        dic[len(str(i))] = [i]

2：将二维数组转换成一堆数组（转换前 lst = [[1,2,3],[4,5,6],[7,8,9]]，转换后lst = [1,2,3,4,5,6,7,8,9]）

list = [[1,2,3],[4,5,6],[7,8,9]]
new_list = []
for i in list:
    new_list.extend(i)
list = new_list

3:一个大小为100G的文件etl_long.txt，要读取文件中的内容，写出具体过程代码。

a=open('etl_log.txt',mode = 'r', encoding = 'utf-8')
print(a.read())
with open('etl_log.txt', 'r', encoding = 'utf-8')as a:
print(a.read())

 

 

4,5,6,7,8,9]