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Difference between as.POSIXct/as.POSIXlt and strptime for converting character vectors to POSIXct/PO
...nd POSIXlt, which stores a list of day, month, year, hour, minute, second, etc.
strptime is a function to directly convert character vectors (of a variety of formats) to POSIXlt format.
as.POSIXlt converts a variety of data types to POSIXlt. It tries to be intelligent and do the sensible thing - i...
When should null values of Boolean be used?
...ean is useful, for example
to store booleans in a collection (List, Map, etc.)
to represent a nullable boolean (coming from a nullable boolean column in a database, for example). The null value might mean "we don't know if it's true or false" in this context.
each time a method needs an Object as ...
How do I concatenate or merge arrays in Swift?
...be propagated to the next operation along the chain (map, flatMap, filter, etc...).
If lazyness makes sense in your particular case, just remember to prepend or append a .lazy to flatten(), for example, modifying Tomasz sample this way:
let c = [a, b].lazy.flatten()
...
How do I intercept a method call in C#?
...wing answer that what should be avoided were Aspect, JointPoint, PointCut, etc. According to Interception documentation from CastleWindsor, none of those are required to accomplish what is asked.
Configure generic registration of an Interceptor, based on the presence of an attribute:
public class ...
How do I write a correct micro-benchmark in Java?
... iterations.)
Rule 2: Always run with -XX:+PrintCompilation, -verbose:gc, etc., so you can verify that the compiler and other parts of the JVM are not doing unexpected work during your timing phase.
Rule 2.1: Print messages at the beginning and end of timing and warmup phases, so you can verify th...
What is a classpath and how do I set it?
...s a "gotcha" with all of the above. On most systems (Linux, Mac OS, UNIX, etc) the colon character (':') is the classpath separator. In windowsm the separator is the semicolon (';')
So what's the best way to do it?
Setting stuff globally via environment variables is bad, generally for the same k...
How is null + true a string?
... | same with System.Single, System.Double, System.Decimal, System.TimeSpan etc
var b = (null + new Object()); // String | same with any ref type
Crazy?? No, there must be a reason behind it.
Someone call Eric Lippert...
s...
How to change max_allowed_packet size
...s:
1) open terminal
2) ssh root@YOURIP
3) enter root password
4) nano /etc/mysql/my.cnf (if command is not recognized do this first or try vi then repeat: yum install nano )
5) add the line: max_allowed_packet=256M (obviously adjust size for whatever you need) under the [MYSQLD] section. He ma...
Difference between >>> and >>
...s a number. For example: Telephone numbers, post codes (in many countries) etc. are strings of decimal digits, but it doesn't make sense to add, subtract or multiply them, so they're not really numbers. They happen to be strings of decimal digits, but should be treated as strings of characters. (Pos...
What are the differences between numpy arrays and matrices? Which one should I use?
...tiply (reduce) two tensors (scalar product,
matrix vector multiplication etc.).
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