• python04



    C:Usersliuwe>python
    Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 17:00:18) [MSC v.1900 64 bit (AMD64)] on win32
    Type "help", "copyright", "credits" or "license" for more information.
    >>> for i in range(3):
    ... print(i)
    ... else:
    ... print("无异常")
    ...
    0
    1
    2
    无异常
    >>> for i in range(3):
    ... print(i)
    ... if i==1:
    ... break
    ... else:
    ... print("无break")
    ...
    0
    1
    >>> while 1:
    ... print(1)
    ... break
    ... else:
    ... print("无break")
    ...
    1

    >>> n=3
    >>> while n>=1:
    ... print(n)
    ... n=n-1
    ... else:
    ... print("无break")
    ...
    3
    2
    1
    无break

    列表,元组和字典:数据结构:存数据的方式

    >>> b=[1]
    >>> type(b)
    <class 'list'>
    >>> a=[]
    >>> a.append(1)
    >>> a
    [1]
    >>> a.append(2)
    >>> a
    [1, 2]
    >>> a.append("a")
    >>> a
    [1, 2, 'a']
    >>> a.insert(0,"s")
    >>> a
    ['s', 1, 2, 'a']
    >>> a.append(2,"x")
    Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    TypeError: append() takes exactly one argument (2 given)
    >>> a.insert(2,"x")
    >>> a
    ['s', 1, 'x', 2, 'a']
    >>>

    >>> a.insert(2,"x")
    >>> a
    ['s', 1, 'x', 2, 'a']
    >>> a.extend(["m","n","z"])
    >>> a
    ['s', 1, 'x', 2, 'a', 'm', 'n', 'z']
    >>>


    >>> del a[0]
    >>> a
    [1, 'x', 2, 'a', 'm', 'n', 'z']
    >>>

    >>> a[0]="ssss"
    >>> a
    ['ssss', 1, 'x', 2, 'a', 'm', 'n', 'z']

    a.remove()

    a.pop()

    列表,元组,字符串都是序列,使用坐标取值

    >>> a=[1,2,3]
    >>> for i in a:
    ... print(i)
    ...
    1
    2
    3

    当需要通过坐标实现计算过程使用如下方法
    >>> for i in range(len(a)):
    ... print(a[i])
    ...
    1
    2
    3
    >>>

    a=list(range(1,11))
    >>> a
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    >>> s=list("abcdef")
    >>> a
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    >>> s
    ['a', 'b', 'c', 'd', 'e', 'f']
    >>> s[2]=1
    >>> s
    ['a', 'b', 1, 'd', 'e', 'f']
    >>> "".join(s)
    Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    TypeError: sequence item 2: expected str instance, int found
    >>> s[2]="1"
    >>> "".join(s)
    'ab1def'
    >>>

    练习

    1.一个list包含了2个a字母,请打印a字母所在的坐标

    思考:用哪种方式可以获取坐标?if

    l=[1,2,3,'a','a',4]

    for i in  range(len(l)):

      if l[i]=a"

        print(i)

        result.append(i)

    print(result)

    2.把两个a字母替换为“*”

    l=[1,2,3,'a','a',4]

    for i in  range(len(l)):

      if l[i]=a"

        print(i)

        result.append(i)

    print(result)

    for i in result:

      l[i]="*":

    print(l)

    3.构造一个list,包含字母和数字的,把全部的数字删除掉

    方法1:过滤思想

    result=[]

    l=[1,2,3,'a','b','c']

    for i in l:

      if not  isinstance(i,(int,float,complex)):

        result.append(i)

    print(result)

    方法2:原有方法基础上去改

    result=[]

    l=[1,2,3,'a','b','c']

    for i in range(len(l)):

      if isinstance(l[i],(int,float,complex)):

        result.append(l[i])

    for i in result:

      l.remove(i)

    print(l)

    元组:元组的内容不能修改

    a=(1,2)

    for i in a : #基于值来进行遍历

      print(i)

    for i in  range(len(a)): #基于坐标的方法进行遍历

      print(a[i])

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  • 原文地址:https://www.cnblogs.com/JacquelineQA/p/14077099.html
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