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Creating an empty list in Python
...y only apply if there is an arg. It's even possible that the C code for [] calls the same C code as list(). In any case the time involved in (c) would be tiny compared with (a) + (b).
– John Machin
Jun 4 '10 at 9:57
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Python multiprocessing PicklingError: Can't pickle
... the one you posted:
Exception in thread Thread-2:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 505, in run
self.__target(*self.__args, **self.__kwargs)
File "/usr/lib/...
How to get the Parent's parent directory in Powershell?
...ame
Version for a file
If $scriptPath points to a file then you have to call Directory property on it first, so the call would look like this
(get-item $scriptPath).Directory.Parent.Parent.FullName
Remarks
This will only work if $scriptPath exists. Otherwise you have to use Split-Path cmdlet.
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How do I plot in real-time in a while loop using matplotlib?
...atter(i, y)
plt.pause(0.05)
plt.show()
Note some of the changes:
Call plt.pause(0.05) to both draw the new data and it runs the GUI's event loop (allowing for mouse interaction).
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How to convert NSNumber to NSString
... but you should take the NSNumber which is inside the array and then call StringValue method, something like NSString *myString= [[myArray objectAtIndex:i] stringValue]; but you have to be sure that you have an NSNumber at that index
– JonLOo
Oct 19 '10 a...
“implements Runnable” vs “extends Thread” in Java
...e just giving it something to run. That means composition is the philosophically "purer" way to go.
In practical terms, it means you can implement Runnable and extend from another class as well.
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Options for HTML scraping? [closed]
... is a lot more pythonic. If you want to try Ruby they ported BeautifulSoup calling it RubyfulSoup but it hasn't been updated in a while.
Other useful tools are HTMLParser or sgmllib.SGMLParser which are part of the standard Python library. These work by calling methods every time you enter/exit a t...
UTF-8 all the way through
...et on all tables and text columns in your database. This makes MySQL physically store and retrieve values encoded natively in UTF-8. Note that MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set).
In older versions of MySQL (< 5....
Creating a new dictionary in Python
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Call dict with no parameters
new_dict = dict()
or simply write
new_dict = {}
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UnboundLocalError on local variable when reassigned after first use
...echanism for locals is fundamentally different for globals - they are statically assigned an offset in the frame's variables table, meaning lookup is a quick index, rather than the more expensive dict lookup as for globals. Because of this, Python is reading the print a line as "get the value of lo...