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List of lists changes reflected across sublists unexpectedly
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When you write [x]*3 you get, essentially, the list [x, x, x]. That is, a list with 3 references to the same x. When you then modify this single x it is visible via all three references to it:
x = [1] * 4
l = [x] * 3
print(f"id(x): {id(x)}")
# id(x): 1405608979...
How assignment works with Python list slice?
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To be clear, "takes a slice of" really means "make a copy of a slice of" which is where part of the confusion comes from.
– Mark Ransom
May 16 '12 at 17:12
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Is there a foreach loop in Go?
...pec#For_range
A "for" statement with a "range" clause iterates through all entries
of an array, slice, string or map, or values received on a channel.
For each entry it assigns iteration values to corresponding iteration
variables and then executes the block.
As an example:
for index, e...
PHP: exceptions vs errors?
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Exceptions are thrown - they are intended to be caught. Errors are generally unrecoverable. Lets say for instance - you have a block of code that will insert a row into a database. It is possible that this call fails (duplicate ID) - you will want to have a "Error" which in this case is an "Exc...
AWS S3 copy files and folders between two buckets
...rows the following error A client error (PermanentRedirect) occurred when calling the ListObjects operation: The bucket you are attempting to access must be addressed using the specified endpoint. Please send all future requests to this endpoint.
– Giovanni Bitliner
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Mediator Vs Observer Object-Oriented Design Patterns
...-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
The Mediator pattern:
Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each o...
Sphinx autodoc is not automatic enough
...for modules project.module1 and project.module2 will be generated automatically and placed into _autosummary directory.
PROJECT
=======
.. toctree::
.. autosummary::
:toctree: _autosummary
project.module1
project.module2
By default autosummary will generate only very short summaries fo...
How to calculate moving average using NumPy?
...5, 13.5, 14.5, 15.5, 16.5, 17.5])
So I guess the answer is: it is really easy to implement, and maybe numpy is already a little bloated with specialized functionality.
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Catching multiple exception types in one catch block
...fining the exceptions). Even given that there are exceptions you want to "fall through", you should still be able to define a hierarchy to match your needs.
abstract class MyExceptions extends Exception {}
abstract class LetterError extends MyExceptions {}
class AError extends LetterError {}
cla...
Print multiple arguments in Python
...or", name, "is", score)
If you don't want spaces to be inserted automatically by print in the above example, change the sep parameter:
print("Total score for ", name, " is ", score, sep='')
If you're using Python 2, won't be able to use the last two because print isn't a function in Python 2. Y...