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How do I perform the SQL Join equivalent in MongoDB?
...rect. The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join:
https://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <...
Relationship between SciPy and NumPy
SciPy appears to provide most (but not all [1]) of NumPy's functions in its own namespace. In other words, if there's a function named numpy.foo , there's almost certainly a scipy.foo . Most of the time, the two appear to be exactly the same, oftentimes even pointing to the same function object.
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How to create the most compact mapping n → isprime(n) up to a limit N?
Naturally, for bool isprime(number) there would be a data structure I could query.
I define the best algorithm , to be the algorithm that produces a data structure with lowest memory consumption for the range (1, N], where N is a constant.
Just an example of what I am looking for: I could rep...
What are inline namespaces for?
C++11 allows inline namespace s, all members of which are also automatically in the enclosing namespace . I cannot think of any useful application of this -- can somebody please give a brief, succinct example of a situation where an inline namespace is needed and where it is the most idiomatic s...
C++ mark as deprecated
...erface that I want to deprecate with portable C++.
When I Googled for this all I got was a Microsoft specific solution; #pragma deprecated and __declspec(deprecated) .
...
How to implement an ordered, default dict? [duplicate]
...deredDict() and defaultdict() from collections in one object, which shall be an ordered, default dict .
Is this possible?
...
Python class inherits object
... so are numerous, to list some of them:
Support for descriptors. Specifically, the following constructs are made possible with descriptors:
classmethod: A method that receives the class as an implicit argument instead of the instance.
staticmethod: A method that does not receive the implicit ar...
Why does ReSharper tell me “implicitly captured closure”?
... use.
The compiler generates a class for both lambda expressions and puts all variables in that class which are used in the lambda expressions.
So in my example g and i are held in the same class for execution of my delegates. If g is a heavy object with a lot of resources left behind, the garbage...
Underscore vs Double underscore with variables and methods [duplicate]
...
Explanation:
People coming from a C++/Java background are especially prone to
overusing/misusing this "feature". But __private names don't work the
same way as in Java or C++. They just trigger a name mangling whose
purpose is to prevent accidental namespace collisions in subclasses...
How to implement __iter__(self) for a container object (Python)
...
I normally would use a generator function. Each time you use a yield statement, it will add an item to the sequence.
The following will create an iterator that yields five, and then every item in some_list.
def __iter__(self):
...