大约有 47,000 项符合查询结果（耗时：0.0206秒） [XML]
Explicitly select items from a list or tuple
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list( myBigList[i] for i in [87, 342, 217, 998, 500] )
I compared the answers with python 2.5.2:
19.7 usec: [ myBigList[i] for i in [87, 342, 217, 998, 500] ]
20.6 usec: map(myBigList.__getitem__, (87, 342, 217, 998, 500))
22.7 usec: item...
Wait for a void async method
How can I wait for a void async method to finish its job?
6 Answers
6
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Python - Create a list with initial capacity
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def doAppend( size=10000 ):
result = []
for i in range(size):
message= "some unique object %d" % ( i, )
result.append(message)
return result
def doAllocate( size=10000 ):
result=size*[None]
for i in range(size):
message= "some u...
List directory tree structure in python?
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Here's a function to do that with formatting:
import os
def list_files(startpath):
for root, dirs, files in os.walk(startpath):
level = root.replace(startpath, '').count(os.sep)
indent = ' ' * 4 * (level)
print('{}{}/'.format(ind...
warning about too many open figures
...ith all its axes, but leaves the window opened, such that it may be reused for other plots.
plt.close() closes a window, which will be the current window, if not specified otherwise. plt.close('all') will close all open figures.
The reason that del fig does not work is that the pyplot state-machin...
Check if something is (not) in a list in Python
...on the container type that could be less efficient, or even incorrect. See for example bloom filters.
– orlp
May 2 '12 at 0:24
15
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What's the difference between echo, print, and print_r in PHP?
...an array or an object). print_r prints a variable in a more human-readable form: strings are not quoted, type information is omitted, array sizes aren't given, etc.
var_dump is usually more useful than print_r when debugging, in my experience. It's particularly useful when you don't know exactly wh...
Append text to input field
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Note, page refresh or form submit and back on the page will of course add the same appended text each time, so you end up with "more text" then "more textmore text" etc.
– James
Sep 8 at 15:59
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What is the documents directory (NSDocumentDirectory)?
...ans that it can only access files and directories within its own contents. For example Documents and Library.
See the iOS Application Programming Guide.
To access the Documents directory of your applications sandbox, you can use the following:
iOS 8 and newer, this is the recommended method
+ (N...
Convert Django Model object to dict with all of the fields intact
...ango Model object to a dict with all of its fields? All ideally includes foreign keys and fields with editable=False .
1...