大约有 48,000 项符合查询结果（耗时：0.0695秒） [XML]
Moving average or running mean
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UPD: more efficient solutions have been proposed by Alleo and jasaarim.
You can use np.convolve for that:
np.convolve(x, np.ones((N,))/N, mode='valid')
Explanation
The running mean is a case of the mathematical operation of convolution. For the running mean, you slide a win...
Why does NULL = NULL evaluate to false in SQL server
... in a where clause, it always evaluates to false. This is counterintuitive and has caused me many errors. I do understand the IS NULL and IS NOT NULL keywords are the correct way to do it. But why does SQL server behave this way?
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Representing null in JSON
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Let's evaluate the parsing of each:
http://jsfiddle.net/brandonscript/Y2dGv/
var json1 = '{}';
var json2 = '{"myCount": null}';
var json3 = '{"myCount": 0}';
var json4 = '{"myString": ""}';
var json5 = '{"myString": "null"}';
var json6 = '{"myArray": []}';
console.log(JSON.parse(js...
WebSockets protocol vs HTTP
There are many blogs and discussions about websocket and HTTP, and many developers and sites strongly advocate websockets, but i still can not understand why.
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What is the difference between “AS” and “IS” in an Oracle stored procedure?
I see Oracle procedures sometimes written with "AS", and sometimes with "IS" keyword.
6 Answers
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Postgres and Indexes on Foreign Keys and Primary Keys
Does Postgres automatically put indexes on Foreign Keys and Primary Keys? How can I tell? Is there a command that will return all indexes on a table?
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How do I remove a property from a JavaScript object?
...edibly in-depth blog post about the delete statement on their blog, Understanding delete. It is highly recommended.
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How I can I lazily read multiple JSON values from a file/stream in Python?
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Here's a much, much simpler solution. The secret is to try, fail, and use the information in the exception to parse correctly. The only limitation is the file must be seekable.
def stream_read_json(fn):
import json
start_pos = 0
with open(fn, 'r') as f:
while True:
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When is SQLiteOpenHelper onCreate() / onUpgrade() run?
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SQLiteOpenHelper onCreate() and onUpgrade() callbacks are invoked when the database is actually opened, for example by a call to getWritableDatabase(). The database is not opened when the database helper object itself is created.
SQLiteOpenHelper versi...
Hidden Features of Xcode
...h a huge influx of newbies to Xcode, I'm sure there are lots of Xcode tips and tricks to be shared.
89 Answers
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