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How to convert a data frame column to numeric type?
... 3
4 d 4 4 d 4
5 e 5 5 e 5
and let us run:
> sapply(d, mode)
char fake_char fac char_fac num
"character" "character" "numeric" "numeric" "numeric"
> sapply(d, class)
char fake_char fac char...
How to handle many-to-many relationships in a RESTful API?
Imagine you have 2 entities, Player and Team , where players can be on multiple teams. In my data model, I have a table for each entity, and a join table to maintain the relationships. Hibernate is fine at handling this, but how might I expose this relationship in a RESTful API?
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Working with $scope.$emit and $scope.$on
...an I send my $scope object from one controller to another using .$emit and .$on methods?
12 Answers
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Declaring variables inside or outside of a loop
...that str absolutely ought to be declared within the while loop. No ifs, no ands, no buts.
The only case where this rule might be violated is if for some reason it is of vital importance that every clock cycle must be squeezed out of the code, in which case you might want to consider instantiating s...
JavaScript checking for null vs. undefined and difference between == and ===
...hey're falsey:
if (!a) {
// `a` is falsey, which includes `undefined` and `null`
// (and `""`, and `0`, and `NaN`, and [of course] `false`)
}
This is defined by ToBoolean in the spec.
...and what is the difference between the null and undefined?
They're both values usually used to i...
How to get image height and width using java?
Is there any other way besides using ImageIO.read to get image height and width?
13 Answers
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Type-juggling and (strict) greater/lesser-than comparisons in PHP
PHP is famous for its type-juggling. I must admit it puzzles me, and I'm having a hard time to find out basic logical/fundamental things in comparisons.
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What are the Ruby Gotchas a newbie should be warned about? [closed]
I have recently learned the Ruby programming language, and all in all it is a good language. But I was quite surprised to see that it was not as simple as I had expected. More precisely, the "rule of least-surprise" did not seem very respected to me (of course this is quite subjective). For examp...
How to prevent a background process from being stopped after closing SSH client in Linux
...ought I could do that by starting the process in background (with an ampersand at the end of the command) and redirecting stdout to a file.
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Looping in a spiral
...algorithm that would let him loop through the elements of an NxM matrix (N and M are odd). I came up with a solution, but I wanted to see if my fellow SO'ers could come up with a better solution.
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