Detailed introduction to python tuples and dictionaries

1. Tuple

##1. Tuple expression

（1,2,3,4）
（'olive',123）
（"python",）

Create tuple:

a=tuple((1,2,3,))
b=("python",)

2. Tuple functionsAttributes

class tuple(object):
    """
    tuple() -> empty tuple
    tuple(iterable) -> tuple initialized from iterable's items
    
    If the argument is a tuple, the return value is the same object.
    """
    def count(self, value): # real signature unknown; restored from __doc__
        """ T.count(value) -> integer -- return number of occurrences of value """
        return 0
    def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
        """
        T.index(value, [start, [stop]]) -> integer -- return first index of value.
        Raises ValueError if the value is not present.
        """
        return 0
    def __add__(self, *args, **kwargs): # real signature unknown
        """ Return self+value. """
        pass
    def __contains__(self, *args, **kwargs): # real signature unknown
        """ Return key in self. """
        pass
    def __eq__(self, *args, **kwargs): # real signature unknown
        """ Return self==value. """
        pass
    def __getattribute__(self, *args, **kwargs): # real signature unknown
        """ Return getattr(self, name). """
        pass
    def __getitem__(self, *args, **kwargs): # real signature unknown
        """ Return self[key]. """
        pass
    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass
    def __ge__(self, *args, **kwargs): # real signature unknown
        """ Return self>=value. """
        pass
    def __gt__(self, *args, **kwargs): # real signature unknown
        """ Return self>value. """
        pass
    def __hash__(self, *args, **kwargs): # real signature unknown
        """ Return hash(self). """
        pass
    def __init__(self, seq=()): # known special case of tuple.__init__
        """
        tuple() -> empty tuple
        tuple(iterable) -> tuple initialized from iterable's items
        
        If the argument is a tuple, the return value is the same object.
        # (copied from class doc)
        """
        pass
    def __iter__(self, *args, **kwargs): # real signature unknown
        """ Implement iter(self). """
        pass
    def __len__(self, *args, **kwargs): # real signature unknown
        """ Return len(self). """
        pass
    def __le__(self, *args, **kwargs): # real signature unknown
        """ Return self<p style="text-align: left;">3. Introduction to some functional attributes of tuples<strong></strong></p>Tuples and lists have Very similar, but the elements of tuples cannot be modified, so many functions that lists have are not available in tuples. <p style="text-align: left;"></p><p style="text-align: left;">1) count(self, value):<span style="background-color: #00ffff"></span></p> Counts the number of value elements in the tuple and returns an int value. <p style="text-align: left;"></p><pre class="brush:php;toolbar:false">a=(1,2,3,4,1,2,3,1,2,)
b=a.count(1)
print(a,type(a))
print(b,type(b))
#运行结果
(1, 2, 3, 4, 1, 2, 3, 1, 2) <class>
3 <class>
demo</class></class>

2)index(self, value, start=None, stop=None):

Index, find the value element in the tuple The first appearing position, start and stop parameters are the starting and ending positions of the search. The default is None and the int value is returned. If this element is not included in the search, a ValueError: 'f' is not in tuple is returned.

a=(1,2,3,4,1,2,3,1,2,)
b=a.index(3)
print(a,len(a))
print(b,type(b))
#运行结果
(1, 2, 3, 4, 1, 2, 3, 1, 2) 9
2 <class>
demo</class>

3) add(self, *args, **kwargs):

Add a new element to the tuple. The new element added needs to Add as a tuple, generating a new tuple.

a=(1,2,3,4)
b=a.__add__((5,1))   #括号理给出的必须是元组
print(a,type(a))
print(b,type(b))
#运行结果
(1, 2, 3, 4) <class>
(1, 2, 3, 4, 5, 1) <class>
demo</class></class>

4) contains(self, *args, **kwargs):

Determine whether the tuple contains an element and return Boolean value.

a=(1,2,3,4,1,2,3,1,2,)
b=a.__contains__(2)
c=a.__contains__(5)
print(a)
print(b)
print(c)
#运行结果
(1, 2, 3, 4, 1, 2, 3, 1, 2)
True
False
demo

2. Dictionary

1. Dictionary expression

{"name":"olive","age":18}

Create dictionary:

a={"name":"olive","age":18}
b=dict({"name":"lusi","age":18})

2. Dictionary functional attributes

class dict(object):
    """
    dict() -> new empty dictionary
    dict(mapping) -> new dictionary initialized from a mapping object's
        (key, value) pairs
    dict(iterable) -> new dictionary initialized as if via:
        d = {}
        for k, v in iterable:
            d[k] = v
    dict(**kwargs) -> new dictionary initialized with the name=value pairs
        in the keyword argument list.  For example:  dict(one=1, two=2)
    """
    def clear(self): # real signature unknown; restored from __doc__
        """ D.clear() -> None.  Remove all items from D. """
        pass
    def copy(self): # real signature unknown; restored from __doc__
        """ D.copy() -> a shallow copy of D """
        pass
    @staticmethod # known case
    def fromkeys(*args, **kwargs): # real signature unknown
        """ Returns a new dict with keys from iterable and values equal to value. """
        pass
    def get(self, k, d=None): # real signature unknown; restored from __doc__
        """ D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None. """
        pass
    def items(self): # real signature unknown; restored from __doc__
        """ D.items() -> a set-like object providing a view on D's items """
        pass
    def keys(self): # real signature unknown; restored from __doc__
        """ D.keys() -> a set-like object providing a view on D's keys """
        pass
    def pop(self, k, d=None): # real signature unknown; restored from __doc__
        """
        D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
        If key is not found, d is returned if given, otherwise KeyError is raised
        """
        pass
    def popitem(self): # real signature unknown; restored from __doc__
        """
        D.popitem() -> (k, v), remove and return some (key, value) pair as a
        2-tuple; but raise KeyError if D is empty.
        """
        pass
    def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
        """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """
        pass
    def update(self, E=None, **F): # known special case of dict.update
        """
        D.update([E, ]**F) -> None.  Update D from dict/iterable E and F.
        If E is present and has a .keys() method, then does:  for k in E: D[k] = E[k]
        If E is present and lacks a .keys() method, then does:  for k, v in E: D[k] = v
        In either case, this is followed by: for k in F:  D[k] = F[k]
        """
        pass
    def values(self): # real signature unknown; restored from __doc__
        """ D.values() -> an object providing a view on D's values """
        pass
    def __contains__(self, *args, **kwargs): # real signature unknown
        """ True if D has a key k, else False. """
        pass
    def __delitem__(self, *args, **kwargs): # real signature unknown
        """ Delete self[key]. """
        pass
    def __eq__(self, *args, **kwargs): # real signature unknown
        """ Return self==value. """
        pass
    def __getattribute__(self, *args, **kwargs): # real signature unknown
        """ Return getattr(self, name). """
        pass
    def __getitem__(self, y): # real signature unknown; restored from __doc__
        """ x.__getitem__(y)  x[y] """
        pass
    def __ge__(self, *args, **kwargs): # real signature unknown
        """ Return self>=value. """
        pass
    def __gt__(self, *args, **kwargs): # real signature unknown
        """ Return self>value. """
        pass
    def __init__(self, seq=None, **kwargs): # known special case of dict.__init__
        """
        dict() -> new empty dictionary
        dict(mapping) -> new dictionary initialized from a mapping object's
            (key, value) pairs
        dict(iterable) -> new dictionary initialized as if via:
            d = {}
            for k, v in iterable:
                d[k] = v
        dict(**kwargs) -> new dictionary initialized with the name=value pairs
            in the keyword argument list.  For example:  dict(one=1, two=2)
        # (copied from class doc)
        """
        pass
    def __iter__(self, *args, **kwargs): # real signature unknown
        """ Implement iter(self). """
        pass
    def __len__(self, *args, **kwargs): # real signature unknown
        """ Return len(self). """
        pass
    def __le__(self, *args, **kwargs): # real signature unknown
        """ Return self size of D in memory, in bytes """
        pass
    __hash__ = None
dict

3. Introduction to some functional attributes of the dictionary
1) clear(self):

Clear all elements in the dictionary.

a={"name":"olive","age":18}
b=a.clear()
print(a)
print(b)
#运行结果
{}
None

2) copy(self):

Copy a tuple, which is equivalent to a shallow copy.

a={"name": "olive","age":18}
b=a.copy()
print(a,id(a),id("name"))
print(b,id(b),id("name"))
#赋值
c={"name": "lusi","age":18}
d=c
print(c,id("name"))
print(d,id("name"))
#浅拷贝
e={"name": "shy","age":18}
f=copy.copy(e)
print(e,id(e),id("name"))
print(f,id(f),id("name"))
#运行结果
{'name': 'olive', 'age': 18} 2915224 2019840
{'name': 'olive', 'age': 18} 2915304 2019840
{'name': 'lusi', 'age': 18} 2019840
{'name': 'lusi', 'age': 18} 2019840
{'name': 'shy', 'age': 18} 5584616 2019840
{'name': 'shy', 'age': 18} 5586056 2019840

3) fromkeys(*args, **kwargs):[fromkeys(seq,value=None)]

Create a new dictionary, with seq as The keys of the dictionary, value is the value of the dictionary, and the default is None. Suitable for creating a dictionary of identical values.

a={"hunan": "changsha","guangdong":"guangzhou","jiangsu":"nanjing",'hubei':"wuhan"}
b=dict.fromkeys(a,"good")
c=dict.fromkeys(["a","b","c"],"abc")
d=dict.fromkeys("abcc")           
print(a)
print(b)
print(c)
print(d)
#运行结果
{'guangdong': 'guangzhou', 'hubei': 'wuhan', 'hunan': 'changsha', 'jiangsu': 'nanjing'}
{'hubei': 'good', 'guangdong': 'good', 'hunan': 'good', 'jiangsu': 'good'}
{'c': 'abc', 'b': 'abc', 'a': 'abc'}
{'c': None, 'b': None, 'a': None}   #seq给出的字符串c是重复的，但是创建的键只取一个。

4) get(self, k, d=None):

Get the value with key k in the dictionary, If k is not contained in the dictionary, the value of d is given, and d defaults to None.

a={"a":1,"b":2,"c":3,"d":4}
b=a.get("a")
c=a.get("e")
d=a.get("e",5)
print(a)
print(b)
print(c)
print(d)
#运行结果
{'b': 2, 'a': 1, 'c': 3, 'd': 4}
1
None
5

5)items(self):

A method to traverse the dictionary and combine each pair of key and value in the dictionary A tuple and returns these tuples in a list-like dict_items.

a={"a":1,"b":2,"c":3,"d":4}
b=a.items()
print(a)
print(b,type(b))
#运行结果
{'d': 4, 'c': 3, 'a': 1, 'b': 2}
dict_items([('d', 4), ('c', 3), ('a', 1), ('b', 2)]) <class></class>

6) keys(self):

A method to traverse dictionary keys keys and return a list-like dict_keys, which is the same as the items method.

a={"a":1,"b":2,"c":3,"d":4}
b=a.keys()
print(a)
print(b,type(b))
#运行结果
{'b': 2, 'a': 1, 'c': 3, 'd': 4}
dict_keys(['b', 'a', 'c', 'd']) <class></class>

7)values(self):

A method to traverse the dictionary value value and return a list-like dict_values, Same usage as items method.

a={"a":1,"b":2,"c":3,"d":4}
b=a.values()
print(a)
print(b,type(b))
#运行结果
{'c': 3, 'd': 4, 'b': 2, 'a': 1}
dict_values([3, 4, 2, 1]) <class></class>

8)pop(self, k, d=None):

and get method The usage is similar, except that get is to get the value with key k in the dictionary, while pop is to get the value with key k in the dictionary. When the key k is not included in the dictionary and d is not the default value, the value obtained is the d value. If d is the default value None, a KeyError is reported.

a={"a":1,"b":2,"c":3,"d":4}
b=a.pop("a")
c=a.pop("e","five")
print(a)
print(b,type(b))
print(c,type(c))
#运行结果
{'c': 3, 'd': 4, 'b': 2}
1 <class>
five <class></class></class>

9)popitem(self):

从字典中随机取出一组键值，返回一个新的元组。如果字典中无键值可取，则KeyError报错。

a={"a":1,"b":2,"c":3,"d":4}
b=a.popitem()
print(a)
print(b,type(b))
#运行结果
{'d': 4, 'b': 2, 'a': 1}
('c', 3) <class></class>

10）setdefault(self, k, d=None):

从字典中获取键为k的值，当字典中包含键k值时，功能和get基本一致，当字典中不包含键k值时，在原字典上添加上键为k的初始键值对，并返回值d。

a={"a":1,"b":2,"c":3,"d":4}
b=a.setdefault("a")
c=a.setdefault("e")
d=a.setdefault("f",6)
print(a)
print(b)
print(c)
print(d)
#运行结果
{'f': 6, 'c': 3, 'a': 1, 'e': None, 'b': 2, 'd': 4}
1
None
6

11）update(self, E=None, **F):

给字典新增元素，没有返回值。用法：dict.update(dict2)。

a={"a":1,"b":2,"c":3,"d":4}
b=a.update({"e":5})
print(a)
print(b)
#运行结果
{'c': 3, 'b': 2, 'd': 4, 'a': 1, 'e': 5}
None

12）contains(self, *args, **kwargs):

判断列表中是否包含某个键值对，返回布尔值。用法：dict.contains(keys)。

a={"a":1,"b":2,"c":3,"d":4}
b=a.__contains__("a")
print(a)
print(b)
#运行结果
{'a': 1, 'd': 4, 'c': 3, 'b': 2}
True

13）delitem(self, *args, **kwargs):

删除字典中的某个键值对，没有返回值。用法：dict.delitem(keys)。

a={"a":1,"b":2,"c":3,"d":4}
b=a.__delitem__("a")
print(a)
print(b)
#运行结果
{'c': 3, 'b': 2, 'd': 4}
None

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