变量及类型

import numpy as np
# 单行注释
"""
三个单引号, 三个双引号
"""
print("hello")
# 变量  variable
# 变量名 = 变量值  ==

name = "lupeng"
print(name)
name = "eric"
print(name)
age = 1
# age = age + 18
age += 18
print(age)
# 变量是有类型的, 用type()可以测量变量的类型
print(type(name)) #<class 'str'>

print(type(age))  # <class 'int'>
print(type(2.22))

arr1 = np.array([0,0,0,1,1,1])
print(type(arr1))

列表

# 常用数据类型
# 1 number  2 string  3 list
#  每个元素可以是不同的数据类型
stu_list = ["张三", "李四", "王五", 11, 99.9, [22, 333]]
print(stu_list)
print(type(stu_list))  # <class 'list'>
# 列表中元素个数
print(len(stu_list))
print(len("haha"))
print(len("张三"))
# 查询
# 列表名[索引]
print(stu_list[0])
print(stu_list[1])
# 增加  末尾追加
stu_list.append("赵六")
stu_list.append("田七")
print(stu_list)
# 修改
stu_list[3] = "哈哈"
print(stu_list)
# 删除
# del stu_list
# print(stu_list)
del stu_list[4]
del stu_list[4]
print(stu_list)

基本操作1

# 列表的常见操作
# [0, 1, 2, 3, 4...9]
# 声明一个空列表
li = []
#  起始  终止  步长
for i in range(1, 11, 2):
    print(i)
    li.append(i)
    print(li)
# 迭代 /遍历  :就是一个一个取出
# for i in [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]:
#     print(i)
li2 = []
for i in range(10):
    li2.append("haha")
print(li2)
# 模拟生成全班 11个人的数学成绩
from random import randint
# [左闭右闭]
print(randint(40, 100))
li3 = []
for i in range(11):
    num = randint(40, 100)
    li3.append(num)
print(li3)

基本操作2

from random import randint
li3 = []
for i in range(11):
    num = randint(1, 100)
    li3.append(num)
print(li3)

# 偶数筛选出来
li4 = []
for num in li3:
    if num%2 == 0:  # 取余数
        li4.append(num)
print(li4)