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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: <...
How to load all modules in a folder?
...
List all python (.py) files in the current folder and put them as __all__ variable in __init__.py
from os.path import dirname, basename, isfile, join
import glob
modules = glob.glob(join(dirname(__file__), "*.py"))
__all__ = [ ba...
In Python, how do I determine if an object is iterable?
...e a method like isiterable ? The only solution I have found so far is to call
21 Answers
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How do I check OS with a preprocessor directive?
...Unix (Linux, *BSD, Mac OS X)
See this related question on some of the pitfalls of using this check.
unix
__unix
__unix__
Mac OS X
__APPLE__
__MACH__
Both are defined; checking for either should work.
Linux
__linux__
linux Obsolete (not POSIX compliant)
__linux Obsolete (not POSIX compliant)
...
Convert base-2 binary number string to int
... (as suggested by the >>> prompt), you don't need to use print at all. The OP's hypothetical example didn't. So it really should be identical in Python 2 and 3.
– John Y
Jul 12 '16 at 22:36
...
Append an object to a list in R in amortized constant time, O(1)?
...irthday. Some kind readers keep repeating any shortcomings with it, so by all means also see some of the comments below. One suggestion for list types:
newlist <- list(oldlist, list(someobj))
In general, R types can make it hard to have one and just one idiom for all types and uses.
...
Is it possible to move/rename files in Git and maintain their history?
...answer, indicates that it's an intentional design choice of Git since it's allegedly much more powerful than tracking renames etc.
– Emil Lundberg
Sep 6 '13 at 14:58
132
...
Odd behavior when Java converts int to byte?
...+ unsignedByte);
Would print out: "Signed: -1 Unsigned: 255"
What's actually happening here?
We are using bitwise AND to mask all of the extraneous sign bits (the 1's to the left of the least significant 8 bits.)
When an int is converted into a byte, Java chops-off the left-most 24 bits
111111...
Can't pickle when using multiprocessing Pool.map()
...nsider it "easy" or not;-) is to add the infrastructure to your program to allow such methods to be pickled, registering it with the copy_reg standard library method.
For example, Steven Bethard's contribution to this thread (towards the end of the thread) shows one perfectly workable approach to a...
Convert sqlalchemy row object to python dict
...of a SQLAlchemy object, like the following::
for u in session.query(User).all():
print u.__dict__
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