大约有 40,000 项符合查询结果（耗时：0.0592秒） [XML]
How do I check if a variable exists?
...have nested functions, variables in outer scopes. If you want to check for all of them, you're probably best off triggering NameError after all.
– Petr Viktorin
Jun 10 '14 at 20:18
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How to update a plot in matplotlib?
I'm having issues with redrawing the figure here. I allow the user to specify the units in the time scale (x-axis) and then I recalculate and call this function plots() . I want the plot to simply update, not append another plot to the figure.
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How do I extract a sub-hash from a hash?
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If you specifically want the method to return the extracted elements but h1 to remain the same:
h1 = {:a => :A, :b => :B, :c => :C, :d => :D}
h2 = h1.select {|key, value| [:b, :d, :e, :f].include?(key) } # => {:b=>:B, :d=...
Why hasn't functional programming taken over yet?
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Because all those advantages are also disadvantages.
Stateless programs; No side effects
Real-world programs are all about side effects and mutation. When the user presses a button it's because they want something to happen. Wh...
How to convert Nonetype to int or string?
I've got an Nonetype value x , it's generally a number, but could be None . I want to divide it by a number, but Python raises:
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Explicitly select items from a list or tuple
... myBigList[i] for i in [87, 342, 217, 998, 500] ]
20.6 usec: map(myBigList.__getitem__, (87, 342, 217, 998, 500))
22.7 usec: itemgetter(87, 342, 217, 998, 500)(myBigList)
24.6 usec: list( myBigList[i] for i in [87, 342, 217, 998, 500] )
Note that in Python 3, the 1st was changed to be the same as ...
The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value
...orm (headline, story, and image). ApplyPropertyChanges applies changes to all properties of the object, including your uninitialized DateTime, which is set to 0001-01-01, which is outside of the range of SQL Server's DATETIME.
Rather than using ApplyPropertyChanges, I'd suggest retrieving the obje...
How to read a file in reverse order?
...A correct, efficient answer written as a generator.
import os
def reverse_readline(filename, buf_size=8192):
"""A generator that returns the lines of a file in reverse order"""
with open(filename) as fh:
segment = None
offset = 0
fh.seek(0, os.SEEK_END)
file...
How to tell Jackson to ignore a field during serialization if its value is null?
... It's deprecated but if you need to maintain old stuff this answer is totally fine! so thanks @WTK :)
– DominikAngerer
Jan 21 '15 at 10:33
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Finding out the name of the original repository you cloned from in Git
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In the repository root, the .git/config file holds all information about remote repositories and branches. In your example, you should look for something like:
[remote "origin"]
fetch = +refs/heads/*:refs/remotes/origin/*
url = server:gitRepo.git
Also, the Git comm...