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How do I check for a network connection?
What is the best way to determine if there is a network connection available?
4 Answers
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SQL join: selecting the last records in a one-to-many relationship
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If you want to include customers who never made a purchase, then change JOIN purchase p1 ON (c.id = p1.customer_id) to LEFT JOIN purchase p1 ON (c.id = p1.customer_id)
– GordonM
Dec 8 '1...
Precise Financial Calculation in JavaScript. What Are the Gotchas?
...now what mistakes to avoid when using JavaScript to do this type of math—if it is possible at all!
7 Answers
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UIScrollView scroll to bottom programmatically
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It wil not work properly if contentSize is lower than bounds. So it should be like this: scrollView.setContentOffset(CGPointMake(0, max(scrollView.contentSize.height - scrollView.bounds.size.height, 0) ), animated: true)
– Bart...
Efficiently checking if arbitrary object is NaN in Python / numpy / pandas?
...oduced, which is why pandas has the tools to deal with it.
Datetimes too (if you use pd.NaT you won't need to specify the dtype)
In [24]: s = Series([Timestamp('20130101'),np.nan,Timestamp('20130102 9:30')],dtype='M8[ns]')
In [25]: s
Out[25]:
0 2013-01-01 00:00:00
1 NaT
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How to express a NOT IN query with ActiveRecord/Rails?
Just to update this since it seems a lot of people come to this, if you are using Rails 4 look at the answers by Trung Lê` and VinniVidiVicci.
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“SetPropertiesRule” warning message when starting Tomcat from Eclipse [duplicate]
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Correct answer, never 'ignore' warnings if at all possible. Ignore enough warnings, some day they'll cause you to miss a REAL problem.
– Manius
Oct 18 '10 at 1:38
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Mongo: find items that don't have a certain field
...e using $exists:
db.things.find( { a : { $exists : false } } ); // return if a is missing
When is true, $exists matches the documents that contain the field, including documents where the field value is null. If is false, the query returns only the documents that do not contain the field.
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Data structure: insert, remove, contains, get random element, all at O(1)
... I don't know of any hashtables that let you get an element like that, and if there are any, I can't imagine that this would be a constant time operation. I would be interested to be proven wrong on either count.
– guildner
Apr 16 '11 at 6:10
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Replace Line Breaks in a String C#
...lacement text"); //add a line terminating ;
As mentioned in other posts, if the string comes from another environment (OS) then you'd need to replace that particular environments implementation of new line control characters.
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