Ternary expressions of Day4_python, list derivation, generator expressions

One or three meta-expressions

Name=input (' name >>: ') res= ' SB ' If name = ' Alex ' Else ' NB ' Print (res)

Second, list analysis

L = []for i in range]:    If I >= 5:        l.append (' egg%s '% i) print (L) # # # #列表解析l = [' egg%s '% i for I in range (Ten) I F I >= 5]print (l)

Third, generator expression

g = (' egg%s '% i for I in range)   # # #用在数据量比较大的场景下print (g) Print (Next (g)) print (Next (g)) print (next) ########## ###################################### #把a文件里的内容最长的一行打印出来with Open (' a.txt ', encoding= ' utf-8 ') as F:    # Res=max (( Len (line), line, F))  ###[len (line) for line on F]    res = max (len (line), line, F) # # # # # # # # # # # # # # # # # # (Len Line) n f), count the length of each line    print (res) print (max ([1, 2, 3, 4, 5, 6]) # # # #求列表中最大值 # # # # # # # # # # # # # #此方法适用大文件with Open (' a.txt ', encoding= ' utf-8 ') As f:    g = (len (line) to line in F)    print (max (g))

Iv. Application

res = SUM (i for I in range (3))    #sum求和print (RES)

‘‘‘
1. How much does it cost to pay for the total?
Db.txt File Contents:

Apple 10 3
Tesla 100000 1
MAC 3000 2
Lenovo 30000 3
Chicken 10 3

‘‘‘

# # # #笨拙的方法with Open (' Db.txt ', encoding= ' utf-8 ') as f:    l = [] for line in    f:        goods = Line.split () # #取出每一行按空格做切分 C3/>price = float (goods[1]) # # #取出商品的价钱        count = Int (goods[2]) # # # #取出商品的个数 Cost        = Price * count### #价钱乘以个数        L.append (cost) #加入到列表中    print (SUM (l))  # 196060.0### #利用生成器表达式with open (' Db.txt ', encoding= ' utf-8 ') as F:    l = (Float (line.split () [1]) * INT (Line.split () [2]) for line in F)    print (SUM (l)) # # #把db文件里的商品取出来放到一个列表里去, end implementation [{' Name ': ' Apple ', ' price ': 333, ' Count ': 3},]with open (' Db.txt ', encoding= ' utf-8 ') as f:    info = [{' Name ': Line.split () [0],             ' price ': float (Line.split () [1]),             ' Count ': Int. (Line.split () [2])} for line in F if float (Line.split () [1]) > = 30000]    print (info)

Ternary expressions of Day4_python, list derivation, generator expressions