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Python: fastest way to create a list of n lists
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The probably only way which is marginally faster than
d = [[] for x in xrange(n)]
is
from itertools import repeat
d = [[] for i in repeat(None, n)]
It does not have to create a new int object in every iteration and is about 15 % faster on my machine.
Edi...
Python Flask, how to set content type
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Try like this:
from flask import Response
@app.route('/ajax_ddl')
def ajax_ddl():
xml = 'foo'
return Response(xml, mimetype='text/xml')
The actual Content-Type is based on the mimetype parameter and the charset (defaults to UTF-8).
Response (and request) objects are docume...
If Python is interpreted, what are .pyc files?
...'translated'. Python is then compiled to a bytecode. AFAIK, only Bash is really interpreted , all other popular "interpreted" languages are all compiled to a bytecode.
– bfontaine
Aug 6 '14 at 13:42
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How do I pass extra arguments to a Python decorator?
... it needs to return another function which is the actual decorator:
def my_decorator(param):
def actual_decorator(func):
print("Decorating function {}, with parameter {}".format(func.__name__, param))
return function_wrapper(func) # assume we defined a wrapper somewhere
ret...
Access-control-allow-origin with multiple domains
...onfig I would like to specify more than one domain for the access-control-allow-origin directive. I don't want to use * . I've tried this syntax:
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Error Dropping Database (Can't rmdir '.test\', errno: 17)
Basically, I was taught on how to create a root password using the "mysqladmin -u root -p password" command, this was done all through the windows command editor. Now, the next process was to display the default databases (info. schema, mysql and test) which was achieved by using "SHOW DATABASES;"
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How to properly import a selfsigned certificate into Java keystore that is available to all Java app
...Windows the easiest way is to use the program portecle.
Download and install portecle.
First make 100% sure you know which JRE or JDK is being used to run your program. On a 64 bit Windows 7 there could be quite a few JREs. Process Explorer can help you with this or you can use: System.out.println...
Performance of Arrays vs. Lists
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Very easy to measure...
In a small number of tight-loop processing code where I know the length is fixed I use arrays for that extra tiny bit of micro-optimisation; arrays can be marginally faster if you use the indexer / for form - but IIRC believe it dep...
How to get the original value of an attribute in Rails
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Before rails 5.1
Appending _was to your attribute will give you the previous value.
For rails 5.1+
Copied from Lucas Andrade's answer below: https://stackoverflow.com/a/50973808/9359123
Appending _was is deprecated in rails 5.1, now you should ap...
How to merge lists into a list of tuples?
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In Python 2:
>>> list_a = [1, 2, 3, 4]
>>> list_b = [5, 6, 7, 8]
>>> zip(list_a, list_b)
[(1, 5), (2, 6), (3, 7), (4, 8)]
In Python 3:
>>> list_a = [1, 2, 3, 4]
>>> list_b = [5, 6, 7, 8]
>>> list(zi...