Python学习笔记——列表②

今天继续了对python中列表数据类型的学习，并且通过对列表的学习掌握"for"循环的方式，range()函数，列表的切片和复制，以及对元组的学习。以下是部分练习题，并通过注释说明了一些需要注意的点。

pizzas=['pizza_1','pizza_2','pizza_3']  #4-1 循环输出列表
                                        #这里用的是列表解析的方式构造列表
for pizza in pizzas:
    print(pizza)
for pizza in pizzas:
    print('I like '+pizza)
print('I really like pizza!\n')

for i in range(1,21):  #4-3 从1数到20
    print(i)
print('\n')

l1=[i for i in range(1,1000001)]  #4-5 计算1到1000000的总和
print(min(l1))
print(max(l1))
print(sum(l1))
print('\n')

l2=[i for i in range(1,21,2)]  #4-6 建立一个奇数列表，这里range的第三个参数是步长
for i in l2:
    print(i)
print('\n')

l3=[i for i in range(3,31,3)]  #4-7 建立一个列表，元素为3的倍数（<=30）
for i in l3:
    print(i)
print('\n')

l4=[i**3 for i in range(1,11)]  #4-8 立方数
for i in l4:
    print(i)
print('\n')

print('The first three items in the l2:')  #4-10 切片
for i in l2[:3]:
    print(i)
print('The last three items in the l2:')
for i in l2[-3:]:
    print(i)
print('The middle three items in the l2:')
mid=int(len(l2)/2)
for i in l2[mid-1:mid+2]:
    print(i)
print('\n')

fri_p=pizzas[:]  #4-11 复制列表，如果不用切片赋值，fri_p将直接指向pizzas，两者为同一列表
pizzas.append('pizza_4')
fri_p.append('pizza_5')
print(pizzas)
print(fri_p)
print('\n')

foods=('food_1','food_2','food_3','food_4','food_5')  #4-13 元组
for food in foods:
    print(food)
foods=('food_1','food_2','food_3','food_6','food_7')  #元组不可修改元素，但可以修改元组变量
for food in foods:
    print(food)
print('\n')

2018/3/14