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What is the purpose of setting a key in data.table?
...two things:
reorders the rows of the data.table DT by the column(s) provided (a, b) by reference, always in increasing order.
marks those columns as key columns by setting an attribute called sorted to DT.
The reordering is both fast (due to data.table's internal radix sorting) and memory effic...
How to update Python?
.... 2.7.4),
different major version of official Python (e.g. 3.3), install side-by-side with old, set paths/associations to point to dominant (e.g. 2.7), shortcut to other (e.g. in BASH $ ln /c/Python33/python.exe python3).
The answer depends:
If OP has 2.7.x and wants to install newer version of...
Git submodule update
...try in the parent repo index), and you will need to add, commit and push said references from the main repo.
Next time you will clone that parent repo, it will populate the submodules to reflect those new SHA1 references.
The rest of this answer details the classic submodule feature (reference to a...
Do I need a Global.asax.cs file at all if I'm using an OWIN Startup.cs class and move all configurat
...ample in a brand new ASP.NET MVC 5 application made from the MVC with Individual Accounts template, if I delete the Global.asax.cs class and move it's configuration code to Startup.cs Configuration() method as follow, what are the downsides?
...
C# 5 async CTP: why is internal “state” set to 0 in generated code before EndAwait call?
...blog, which rocks.
The value 0 here is only special because it's not a valid state which you might be in just before the await in a normal case. In particular, it's not a state which the state machine may end up testing for elsewhere. I believe that using any non-positive value would work just as w...
Select the values of one property on all objects of an array in PowerShell
...
To complement the preexisting, helpful answers with guidance of when to use which approach and a performance comparison.
Outside of a pipeline, use (PSv3+): $objects.Name as demonstrated in rageandqq's answer, which is both syntactically simpler and much faster.
Accessing a pr...
Under what circumstances is an SqlConnection automatically enlisted in an ambient TransactionScope T
...stributed transaction, which can be confirmed by checking for a non-null GUID at Transaction.Current.TransactionInformation.DistributedIdentifier.
*Update: I read somewhere that this is fixed in SQL Server 2008, so that MSDTC is not used when the same connection string is used for both connections (...
How should a model be structured in MVC? [closed]
... not a class or any single object. It is a very common mistake to make (I did too, though the original answer was written when I began to learn otherwise), because most frameworks perpetuate this misconception.
Neither is it an Object-Relational Mapping technique (ORM) nor an abstraction of databas...
Why do == comparisons with Integer.valueOf(String) give different results for 127 and 128?
I have no idea why these lines of code return different values:
5 Answers
5
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Why does my application spend 24% of its life doing a null check?
...d. The next statement is very cheap because the while() statement already did the heavy lifting of retrieving the value from memory. Assigning the local variable is cheap, a processor uses a buffer for writes.
Not otherwise a simple problem to solve, flattening your tree into arrays is very likely ...