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How to Correctly Use Lists in R?
...where the first element is a character vector, the second is a data frame, etc. In this case, you have created two different lists. x has four vectors, each of length 1. x2 has 1 vector of length 4:
> length(x[[1]])
[1] 1
> length(x2[[1]])
[1] 4
So these are completely different lists.
R l...
JavaScript check if variable exists (is defined/initialized)
...(Assuming the variable could hold anything (string, int, object, function, etc.))
28 Answers
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Why doesn't Java allow overriding of static methods?
... are attached to an instance while static methods are attached to a class, etc etc. Still, consider the following code:
public class RegularEmployee {
private BigDecimal salary;
public void setSalary(BigDecimal salary) {
this.salary = salary;
}
public static BigDecimal get...
C# Lambda expressions: Why should I use them?
...# expressions in to the SQL expressions desired for filtering / ordering / etc. on the server side.
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notifyDataSetChanged example
I'm trying to use in my Android Application the notifyDataSetChanged() method for an ArrayAdapter but it doesn't work for me.
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R object identification
...t(d=1:26, e=letters))
data(cars)
obj <- lm(dist ~ speed, data=cars)
..etc.
If obj is an S3 or S4 object, you can also try methods or showMethods, showClass, etc. Patrick Burns' R Inferno has a pretty good section on this (sec #7).
EDIT: Dirk and Hadley mention str(obj) in their answers. It ...
Difference between app.use and app.get in express.js
...l of them and regardless of HTTP verb used:
GET /
PUT /foo
POST /foo/bar
etc.
app.get(), on the other hand, is part of Express' application routing and is intended for matching and handling a specific route when requested with the GET HTTP verb:
GET /
And, the equivalent routing for your exa...
Why should I use IHttpActionResult instead of HttpResponseMessage?
...ide those convenient helper methods of ApiController such as Ok, NotFound, etc.
Basically, I think a class implementing IHttpActionResult as a factory of HttpResponseMessage. With that mind set, it now becomes an object that need to be returned and a factory that produces it. In general programming...
Why are Subjects not recommended in .NET Reactive Extensions?
...or support dev guess at WTF was going on. When you use the Create/Generate etc methods you are localizing the effects on the sequence. You can see it all in one method and you know no-one else is throwing in a nasty side effect. If I see a subject fields I now have to go looking for all the places i...
What is a JavaBean exactly?
...ytes. Those bytes can be stored in files, sent over a network connection, etc, and have enough info to allow a JVM (at least, one that knows about the object's type) to reconstruct the object later -- possibly in a different instance of the application, or even on a whole other machine!
Of course,...