// list array corresponding to high-level language C
storing a plurality of data (a plurality may be any type of data)
is defined in the form:
list1=[12,52,36,63,36]
list2=['liuu','xiaohan','zhangsan'
]
Access: access via an index value
names=['liuwei','zhangsan','xiaoqiang']
print(names[0]) //访问的第0个元素,输出结果为:liuwei
print(names[-1]) //访问最后一个元素。
How to print all of the data list
for circulation by way of printing while loop.
for i in range(len(names)):
print(names[i])
或
for name in names :
print(name)
Operation to the list
by:
the append
Example:
names=[]
names.append("liuwei")
names.append("好凉快") //
print(names)
insert
例:
names=[]
names.insert("翻学啦") //会报错,不知道放在哪,必须制定位置
names.insert(0,"翻学啦") //原元素将向后移
print(names)
extend
例:
names2=['张丹丹','路人甲']
names.extend(names2) //将names2的列表元素逐个加入到names列表中
删:
remove()
例:
names=['liuu','xiaohan','zhangsan']
names.remove('liuu') //只能删除指定的值
del()
例:
names=['liuu','xiaohan','zhangsan']
del names[0] //删除指定索引的值
del names //删除列表,即列表不存在
pop()
例:
names=['liuu','xiaohan','zhangsan']
names.pop(0) //删除指定索引的值
clear()
例:
names=['liuu','xiaohan','zhangsan']
names.clear() //清空列表元素,但列表仍存在
查:
```css
index
例:
names=['liuu','xiaohan','zhangsan']
print(names.index('xiaohan')) //打印xiaohan在列表中的索引值
count
例:
names=['liuu','xiaohan','zhangsan']
print(names.count('xiaohan')) //打印出现的次数,如果为0,证明列表没有这个元素。
改:
```css
步骤:
1.先判断有没有这个元素.
if 'xiaohan' in names
2.找出所在的位置
index1=names.index('xiaohan')
3.修改
names[index1]='王富贵'
列表的排序
sort()
默认是自然顺序排序(从小到大)
list1=[10,25,32,12,11,96,25]
list2=list1.sort()
print(list1) //会安顺排序,对原数据直接操作,不会产生值
print(list2) //是一个空,
sort(reverse)
从大到小排序
列表的嵌套使用
list2=[[1,2,3],[5,6],[10,21,32]]
list2表示一个列表,元素仍然为一个列表。
遍历列表
```css
list2=[[1,2,3],[5,6],[10,21,32]]
for list3 in list2:
if type(list3) == list:
for i in list3:
print(i)
Nested list stored procedure:
Ganso:
Tuple if only one element, must be a comma tuple representation: (element 1, element 2, ...) can not be changed: the value of storage elements, can not be modified, can not be deleted
tuple1 = ( 'student 1', 99) to access the elements via index tuple1 = ( 'student. 1', 99)
Print (suple1 [-1]) of additions and deletions do not support tuples, but supports queries
.
查找:
print(tuple1.index[1])
print(tuple1.count[99])
将元祖转换成列表
list1=list(tuple1) //list可以将其转换成列表
list1[1]=100
tuple1= =tuple(list1) ///将列表转换成元祖,整体在赋值给tuple1
Dictionary:
1. The dictionary definition of the form
{key1: value, key2: value}
Key unique
2.元素的访问
country = {"CN":"中国","JP":"日本"}
print(country['CN'])
打印结果:"中国"
如果没有"CN"这个key,则会报错
3.元素的常用方法
students={'胡来':[],'达瓦':[]}
students['胡来']
修改元素
可以直接进行修改
student={'name':'陈独秀','age':99}
student['age']=100
添加元素
student['address']='北京市朝阳区'
如果字典中没有'address'这个key,则会将这个元素条件到字典中,如果已经包含这个key
则新值会将旧值覆盖
删除元素
del 删除
例:
删除某个key
del student['age']
删除所有的键值对,删除之后,将不能在进行访问
pop('key')
4.元素的遍历
country = {"CN":"中国","JP":"日本","CA":Canada}
all_keys = countries.keys() //单独将KEY取出来
print(all_keys)
for key in all_keys:
print(key)
print(country[key])
print('CN' in all_keys) //判断是否包含某个值
Exercises:
Code:
print("1.添加学生")
print("2.查找学生")
print("3.展示所有")
print("4.删除学生")
print("5.修改学生")
print("6.退出系统")
student_name=['张三','老吴']
student_age=[25,26]
function=int(input("请输入您想要选择的功能,输入对应的数字——》"))
if function == 1:
name=input("请输入姓名——》")
age=int(input("请输入年龄"))
student_name.append(name)
student_age.append(age)
print("恭喜添加成功,姓名:{0}\n年龄:{1}".format(student_name[-1],student_age[-1]))
elif function == 2:
name=input("请输入需要查找的姓名——》")
if student_name.count(name)>0 :
num=student_name.index(name)
print("姓名:{0}\n年龄:{1}".format(student_name[num],student_age[num]))
else :
print("您要查找的姓名不存在")
elif function == 3 :
for i in range(len(student_name)):
print("姓名:{0} ---年龄:{1}".format(student_name[i],student_age[i]))
elif function == 4:
name=input("请输入要删除的姓名")
if student_name.count(name)>0 :
num=student_name.index(name)
student_name.pop(num)
student_age.pop(num)
print("删除成功")
else :
print("您要删除的姓名不存在")
elif function == 5:
name=input("请输入要修改的姓名")
if student_name.count(name) > 0 :
num=student_name.index(name)
print("修改姓名请输入1")
print("修改年龄请输入2")
num1=int(input("请输入:"))
if num1==1 :
new_name=input("新的姓名")
student_name[num]=new_name
else :
new_age=input("请输入修改后的年龄")
student_age[num]=new_age
print('修改成功:{0}{1}'.format(student_name[num],student_age[num]))
else :
print("您要修改的姓名不存在")
else :
pass
function:
In general, a piece of code needs to be reused many times, and this code also have a specific function, we will organize this code as a separate function module, the function module can be called a function
definition and call functionsFunction is defined: def function name (parameter): calling the function name of the function block (arguments)
练习 封装函数打印99乘法表:
def show99():
i = 1
while i < 10:
j = 1
while j <= i:
print("%d * %d = %d\t"%(j,i,i*j),end=" ")
j += 1
i += 1
print("")
函数的调用,只有调用函数,函数中的代码才会被执行
show99()
使用help(自定义方法名) 可以查看函数的文档说明
help(show99)
显示结果:
Help on function show99 in module __main__:
Function parameters
Def method names defined function with parameters (parameters ...): a block of code (with code, parameters can be better appreciated as a variable defined) function call with parameters
method name (actual parameters)