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What is meant by 'first class object'?
...notion of "first-class functions" in a programming language was introduced by British computer scientist Christopher Strachey in the 1960s. The most famous formulation of this principle is probably in Structure and Interpretation of Computer Programs by Gerald Jay Sussman and Harry Abelson:
They m...
PostgreSQL array_agg order
...however. For example:
SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
So in your case you would write:
SELECT
array_to_string(array_agg(animal_name),';') animal_names,
array_to_string(array_agg(animal_type),';') animal_types
FROM (SELECT animal_name, animal_type FROM anima...
Why do we need tuples in Python (or any immutable data type)?
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@ACoolie, that's totally dominated by the random calls (try doing just that, you'll see!), so not very significant. Try python -mtimeit -s "x=23" "[x,x]" and you'll see a more meaningful speedup of 2-3 times for building the tuple vs building the list.
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How to Select Every Row Where Column Value is NOT Distinct
...s] WHERE [EmailAddress] IN
(SELECT [EmailAddress] FROM [Customers] GROUP BY [EmailAddress] HAVING COUNT(*) > 1)
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Your branch is ahead of 'origin/master' by 3 commits
...hich returned Everything up-to-date, after that the message of being ahead by x commits went away.
– Will B.
Nov 11 '14 at 16:28
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What is the difference between Strategy design pattern and State design pattern?
...s are passed to the context object as parameters, while States are created by the context object itself.
Strategies only handle a single, specific task, while States provide the underlying implementation for everything (or most everything) the context object does.
A "classic" implementation would ...
CSS selector by inline style attribute
Is there a CSS selector to select this element by its inline style attribute value?
2 Answers
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What is the id( ) function used for?
...responding C object.
If yes, why doesn't the number increase instantly by the size of the data type (I assume that it would be int)?
Because a list is not an array, and a list element is a reference, not an object.
When do we really use id( ) function?
Hardly ever. id() (or its equivalen...
unix diff side-to-side results?
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From man diff, you can use -y to do side-by-side.
-y, --side-by-side
output in two columns
Hence, say:
diff -y /tmp/test1 /tmp/test2
Test
$ cat a $ cat b
hello hello
my name my name
is me ...
How do you get a directory listing sorted by creation date in python?
What is the best way to get a list of all files in a directory, sorted by date [created | modified], using python, on a windows machine?
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