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Grouping functions (tapply, by, aggregate) and the *apply family
...a function to the 1st elements
of each, and then the 2nd elements of each, etc., coercing the result
to a vector/array as in sapply.
This is multivariate in the sense that your function must accept
multiple arguments.
#Sums the 1st elements, the 2nd elements, etc.
mapply(sum, 1:5, 1:5, 1:5)
[1] ...
Is Fortran easier to optimize than C for heavy calculations?
...ry and technology, this often meant restricting features and capability in order to give the compiler the best shot at optimizing the code. A good analogy is to think of Fortran 77 as a professional race car that sacrifices features for speed. These days compilers have gotten better across all langu...
What is an example of the simplest possible Socket.io example?
.../title>
<style>
* { margin: 0; padding: 0; box-sizing: border-box; }
body { font: 13px Helvetica, Arial; }
form { background: #000; padding: 3px; position: fixed; bottom: 0; width: 100%; }
form input { border: 0; padding: 10px; width: 90%; margin-right: .5%; }
...
How to set Oracle's Java as the default Java in Ubuntu?
...nvironment variables globally and at system level means use should set in /etc/environment file.
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Why doesn't GCC optimize a*a*a*a*a*a to (a*a*a)*(a*a*a)?
... of the answer.
As a result, most compilers are very conservative about reordering floating point calculations unless they can be sure that the answer will stay the same, or unless you tell them you don't care about numerical accuracy. For example: the -fassociative-math option of gcc which allows...
How to change Elasticsearch max memory size
...one of the above answers worked for me.
I tried changing ES_HEAP_SIZE in /etc/default/elasticsearch and in etc/init.d/elasticsearch, but when I ran ps aux | grep elasticsearch the output still showed:
/usr/bin/java -Xms2g -Xmx2g # aka 2G min and max ram
I had to make these changes in:
/etc/elas...
Composite Key with EF 4.1 Code First
...uld work - composite key defined with annotations requires explicit column order:
public class ActivityType
{
[Key, Column(Order = 0)]
public int ActivityID { get; set; }
[Key, Column(Order = 1)]
[Required(ErrorMessage = "A ActivityName is required")]
[StringLength(50, ErrorMes...
Difference between BeautifulSoup and Scrapy crawler?
...an specify constraints on how many (number of) URLs you want to crawl and fetch,etc. It is a complete framework for web-scraping or crawling.
While
BeautifulSoup is a parsing library which also does a pretty good job of fetching contents from URL and allows you to parse certain parts of them witho...
Object comparison in JavaScript [duplicate]
...d DOM nodes inside:
JSON.stringify(obj1) === JSON.stringify(obj2)
The ORDER of the properties IS IMPORTANT, so this method will return false for following objects:
x = {a: 1, b: 2};
y = {b: 2, a: 1};
2) Slow and more generic.
Compares objects without digging into prototypes, then compar...
MySQL: Quick breakdown of the types of joins [duplicate]
...--+------+------+
It makes no difference to INNER JOIN if you reverse the order, because it cares about both tables:
> SELECT * FROM table_b b INNER JOIN table_a a ON a.id=b.aid;
+------+------+------+------+------+
| id | name | aid | id | name |
+------+------+------+------+------+
| 3...