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Django select only rows with duplicate field values
...values('name')
.annotate(Count('id'))
.order_by()
.filter(id__count__gt=1)
This is as close as you can get with Django. The problem is that this will return a ValuesQuerySet with only name and count. However, you can then use this to construct a regula...
Get last result in interactive Python shell
...
Underscore.
>>> 5+5
10
>>> _
10
>>> _ + 5
15
>>> _
15
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Unmangling the result of std::type_info::name
... calling function. This should be relatively easy, standard C++ has a type_info class. This contains the name of the typeid'd class/function/etc. but it's mangled. It's not very useful. I.e. typeid(std::vector<int>).name() returns St6vectorIiSaIiEE .
...
OceanBase使用libeasy原理源码分析：服务器端 - 数据库(内核) - 清泛网 - ...
...、OceanBase启动时的使用模式
二、 基础数据结构
2.1 easy_list_t
2.2 easy_pool_t
2.3 easy_buf_t
2.4 easy_connection_t
三、 连接建立
四、 同步处理(OceanBase少量使用这种模式)
五、 异步处理(OceanBase大量采用这种模式)
六、 资源管理
...
How to mock an import
...importing A to get what you want:
test.py:
import sys
sys.modules['B'] = __import__('mock_B')
import A
print(A.B.__name__)
A.py:
import B
Note B.py does not exist, but when running test.py no error is returned and print(A.B.__name__) prints mock_B. You still have to create a mock_B.py where ...
Pickle or json?
...ccf1b3fa91f4399902bb534/raw/03e8dbab11b5605bc572bc117c8ac34cfa959a70/pickle_vs_json.py
python pickle_vs_json.py
Results with python 2.7 on a decent 2015 Xeon processor:
Dir Entries Method Time Length
dump 10 JSON 0.017 1484510
load 10 JSON 0.375 -
dump 10 Pickle 0.011 ...
sql “LIKE” equivalent in django query
...
Use __contains or __icontains (case-insensitive):
result = table.objects.filter(string__contains='pattern')
The SQL equivalent is
SELECT ... WHERE string LIKE '%pattern%';
...
Get event listeners attached to node using addEventListener
... 'old' prototype methods):
var ListenerTracker=new function(){
var is_active=false;
// listener tracking datas
var _elements_ =[];
var _listeners_ =[];
this.init=function(){
if(!is_active){//avoid duplicate call
intercep_events_listeners();
}
...
List changes unexpectedly after assignment. How do I clone or copy it to prevent this?
While using new_list = my_list , any modifications to new_list changes my_list everytime. Why is this, and how can I clone or copy the list to prevent it?
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Python __str__ and lists
...
Calling string on a python list calls the __repr__ method on each element inside. For some items, __str__ and __repr__ are the same. If you want that behavior, do:
def __str__(self):
...
def __repr__(self):
return self.__str__()
...