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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: <...
Hashing a dictionary?
...e hash():
hash(frozenset(my_dict.items()))
This is much less computationally intensive than generating the JSON string or representation of the dictionary.
UPDATE: Please see the comments below, why this approach might not produce a stable result.
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Remove all occurrences of a value from a list?
...on over the filter+lambda; the former is more readable in addition to generally more efficient.
– habnabit
Jul 21 '09 at 4:28
17
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node.js require all files in a folder?
How do I require all files in a folder in node.js?
14 Answers
14
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Undefined reference to `pow' and `floor'
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Look in /lib or /usr/lib. The libraries are all named lib<name>.a or lib<name>.so - it's the "<name>" you put after the -l. In this case, the math library is named libm.so, so we call it -lm.
– ams
Dec 29 '11 at ...
How do I run all Python unit tests in a directory?
...it test module is of the form test_*.py . I am attempting to make a file called all_test.py that will, you guessed it, run all files in the aforementioned test form and return the result. I have tried two methods so far; both have failed. I will show the two methods, and I hope someone out there ...
Why are Python's 'private' methods not actually private?
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The name scrambling is used to ensure that subclasses don't accidentally override the private methods and attributes of their superclasses. It's not designed to prevent deliberate access from outside.
For example:
>>> class Foo(object):
... def __init__(self):
... self....
How to read data From *.CSV file using javascript?
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NOTE: I concocted this solution before I was reminded about all the "special cases" that can occur in a valid CSV file, like escaped quotes. I'm leaving my answer for those who want something quick and dirty, but I recommend Evan's answer for accuracy.
This code will work when your...
Extracting text from HTML file using Python
...'d like to extract the text from an HTML file using Python. I want essentially the same output I would get if I copied the text from a browser and pasted it into notepad.
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Python read-only property
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Generally, Python programs should be written with the assumption that all users are consenting adults, and thus are responsible for using things correctly themselves. However, in the rare instance where it just does not make sens...