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What is the purpose of setting a key in data.table?
...antage to keying a data.table?
Keying a data.table physically reorders it based on those column(s) in RAM. Computing the order is not usually the time consuming part, rather the reordering itself. However, once we've the data sorted in RAM, the rows belonging to the same group are all contiguous in...
What exactly does stringstream do?
...um, unsigned int prec = 12) {
string ret;
stringstream ss;
ios_base::fmtflags ff = ss.flags();
ff |= ios_base::floatfield;
ff |= ios_base::fixed;
ss.flags(ff);
ss.precision(prec);
ss << num;
ret = ss.str();
return ret;
};
Maybe it's a bit complicated b...
WPF vs Silverlight [duplicate]
...form that has access to the full .Net Framework. Silverlight is a browser-based technology that has access to a subset of the .Net Framework (called the CoreCLR). So, you'll notice differences using seemingly every day methods and objects within the framework. For instance, the Split() method on ...
Difference between is and as keyword
...sages of both the keywords, you will get the difference easily.
C# Code:
BaseClass baseclassInstance = new DerivedClass();
DerivedClass derivedclassInstance;
if (baseclassInstance is DerivedClass)
{
derivedclassInstance = (DerivedClass)baseclassInstance;
// do something on derivedclassInsta...
Difference between Destroy and Delete
... API:
ActiveRecord::Persistence.delete
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted). Returns the frozen instance.
The row is simply removed with an SQL DELETE statement on the record's primary key, a...
Django Cookies, how can I set them?
I have a web site which shows different content based on a location
the visitor chooses. e.g: User enters in 55812 as the zip. I know what
city and area lat/long. that is and give them their content pertinent
to that area. My question is how can I store this in a cookie so that
when they return they...
ActiveRecord: size vs count
...ve built but haven't saved, .count will report only the count from the database.
– Shawn J. Goff
Sep 6 '13 at 18:54
...
Are (non-void) self-closing tags valid in HTML5?
...th most of the inconveniences of XML), while it makes it harder to use XML-based tools (e.g. template tools or various processors). Even from a generation point of view, it would seem that <object data="..." /> and <img src="..."></src> are not OK, while <object data="...">&l...
Docker - how can I copy a file from an image to a host?
...
docker cp $(docker create --rm registry.example.com/ansible-base:latest):/home/ansible/.ssh/id_rsa ./hacked_ssh_key
wanted to supply a one line solution based on pure docker functionality (no bash needed)
edit: container does not even has to be run in this solution
edit2: thanks to @...
Value cannot be null. Parameter name: source
...ed here and mistakenly a table was there that has been delete from the database recently and I never noticed and it returning null with other entities. I just removed the stupid table from the include list and I am good to go. hope this can help somebody.
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