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Dynamically select data frame columns using $ and a character value
...[[var]]
mtcars[var]
You can perform the ordering without loops, using do.call to construct the call to order. Here is a reproducible example below:
# set seed for reproducibility
set.seed(123)
df <- data.frame( col1 = sample(5,10,repl=T) , col2 = sample(5,10,repl=T) , col3 = sample(5,10,repl=...
Pass parameter to controller from @Html.ActionLink MVC 4
... // htmlAttributes
blogPostId = blogPostId,
replyblogPostmodel = Model,
captchaValid = Model.AddNewComment.DisplayCaptcha
}
)
and here's what you should use:
@Html.ActionLink(
"Reply", ...
Cannot deserialize the JSON array (e.g. [1,2,3]) into type ' ' because type requires JSON object (e.
...
FYI this didn't work for me because I was getting my JSON from an API and I had the freaking URL wrong for an entire day. ><
– w00ngy
Oct 5 '18 at 13:14
...
What is the advantage of using abstract classes instead of traits?
...tor parameters
Abstract classes are fully interoperable with Java. You can call them from Java code without any wrappers. Traits are fully interoperable only if they do not contain any implementation code
share
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...
What does “program to interfaces, not implementations” mean?
...our still could still be assuming that random access is fast by repeatedly calling get(i).
– Joachim Sauer
Apr 23 '10 at 11:36
17
...
Iterate through object properties
...y check:
for (var prop in obj) {
if (Object.prototype.hasOwnProperty.call(obj, prop)) {
// do stuff
}
}
It's necessary because an object's prototype contains additional properties for the object which are technically part of the object. These additional properties are inherited f...
How can I scale an image in a CSS sprite
...nline-block;
background: url('../img/icons/icons.png') no-repeat;
width: 64px;
height: 51px;
overflow: hidden;
zoom:0.5;
-moz-transform:scale(0.5);
-moz-transform-origin: 0 0;
}
.icon-huge{
zoom:1;
-moz-transform:scale(1);
-moz-transform-origin: 0 0;
}
.icon...
Why do people write the #!/usr/bin/env python shebang on the first line of a Python script?
...
That is called the shebang line. As the Wikipedia entry explains:
In computing, a shebang (also called a hashbang, hashpling, pound bang, or crunchbang) refers to the characters "#!" when they are the first two characters in an i...
Understanding typedefs for function pointers in C
...les' code which had typedefs for pointers to functions with arguments. I recall that it took me a while to get around to such a definition while trying to understand a numerical algorithm written in C a while ago. So, could you share your tips and thoughts on how to write good typedefs for pointers ...
In C++, what is a virtual base class?
...memory layout, you have:
A A
| |
B C
\ /
D
This explain why when call D::foo(), you have an ambiguity problem. But the real problem comes when you want to use a member variable of A. For example, let's say we have:
class A
{
public :
foo() ;
int m_iValue ;
} ;
When you'l...