1. 推导式（列表推导式、集合推导式、字典推导式）
# ### 推导式 : 通过一行循环判断,遍历出一系列数据的方式是推导式 """ 推导式一共三种: 列表推导式,集合推导式,字典推导式 [val for val in Iterable] {val for val in Iterable} {a:b for a,b in iterable} """ # (1)单循环的推导式 """[1,2,3,4,5,6,7,8 ... 50]""" lst = [] for i in range(1,51): print(i) lst.append(i) print(lst) # 改写成推导式 lst = [val for val in range(1,51)] print(lst) # (2)带有判断条件的单循环推导式 [判断条件只能是单项分支,其他的不可以] """[1,2,3,4,5,6,7,8 ... 50] 要所有的偶数""" lst = [] for i in range(1,51): if i % 2 == 0: lst.append(i) print(lst) # 改写成推导式 lst = [i for i in range(1,51) if i % 2 == 0] print(lst) # (3)多循环推导式 "谁❤谁" lst1 = ["常远","皮得意","纸质红"] lst2 = ["李德亮","林明辉","陈佳琪"] lst_new = [] for i in lst1: for j in lst2: strvar = i + "❤" + j lst_new.append(strvar) print(lst_new) # 改写成推导式 lst = [i + "❤" + j for i in lst1 for j in lst2] print(lst) # (4)带有判断条件的多循环推导式 lst1 = ["常远","皮得意","纸质红"] lst2 = ["李德亮","林明辉","陈佳琪"] lst_new = [] for i in lst1: for j in lst2: if lst1.index(i) == lst2.index(j): strvar = i + "❤" + j lst_new.append(strvar) print(lst_new) # 改写成推导式 lst = [i + "❤" + j for i in lst1 for j in lst2 if lst1.index(i) == lst2.index(j)] print(lst)