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Extract a dplyr tbl column as a vector
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This seems the most versatile method as it works identically with vectors and data.frames, i.e. it enables functions to be more agnostic.
– geotheory
Mar 14 '17 at 10:03
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What is “Orthogonality”?
...gn, operations do not have side effects; each action (whether it's an API call, a macro invocation, or a language operation) changes just one thing without affecting others. There is one and only one way to change each property of whatever system you are controlling.
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通过FastCGI Cache实现服务降级 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...，架构图如下：
Degradation
实现的关键点在于通过error_page处理异常，并且完成服务降级：
limit_conn_zone $server_name zone=perserver:1m;
error_page 500 502 503 504 = @failover;
fastcgi_cache_path
/tmp
levels=1:2
keys_zone=failover:100m
i...
Ruby - test for array
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Type checking is for Java. Go ahead and just call count on the variable. Write unit tests to make sure the method works as expected.
– user132447
Mar 21 '12 at 14:55
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What is in your .vimrc? [closed]
Vi and Vim allow for really awesome customization, typically stored inside a .vimrc file. Typical features for a programmer would be syntax highlighting, smart indenting and so on.
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django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb
...ysql-python
When I did the above, I got the error "EnvironmentError: mysql_config not found"
To fix this, I did the below in terminal:
export PATH=$PATH:/usr/local/mysql/bin
When I reran step 1, I get a new error "error: command 'cc' failed with exit status 1"
To fix this, I did the...
Excel: last character/string match in a string
...(2,1/(MID(A4,SEQUENCE(LEN(A4)),2)="YY")) | 4 |
Whilst this both allows us to no longer use an arbitrary replacement character and it allows overlapping patterns, the "downside" is the useage of an array.
Note: You can force the same behaviour in older Excel versions through either
=M...
Any reason to prefer getClass() over instanceof when generating .equals()?
...try must apply, and instanceof makes it very easy to be asymmetric accidentally
– Scott Stanchfield
Mar 3 '09 at 20:15
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iPad keyboard will not dismiss if modal ViewController presentation style is UIModalPresentationForm
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In the view controller that is presented modally, just override disablesAutomaticKeyboardDismissal to return NO:
- (BOOL)disablesAutomaticKeyboardDismissal {
return NO;
}
share
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How do I scroll the UIScrollView when the keyboard appears?
... handling of this issue is explained. You should have a look into it.
// Call this method somewhere in your view controller setup code.
- (void)registerForKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWasShown:)
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