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Evaluate expression given as a string
...s("5+5")
[1] "character"
> class(parse(text="5+5"))
[1] "expression"
Calling eval() invokes many behaviours, some are not immediately obvious:
> class(eval(parse(text="5+5")))
[1] "numeric"
> class(eval(parse(text="gray")))
[1] "function"
> class(eval(parse(text="blue")))
Error in eva...
Error renaming a column in MySQL
...
Keep in mind that in this solution you lose all other column definitions such as nullability, default value, etc. (see: stackoverflow.com/questions/8553130/…).
– Dejan
Jul 13 '15 at 10:50
...
git reset --hard HEAD leaves untracked files behind
...rking copy.
If you need to reset the whole repository to master including all git submodules, run this script:
git reset --hard HEAD
git clean -f -d
git checkout master
git fetch origin master
git reset --hard origin/master
git pull
git submodule update
git submodule update --init --recursive
git ...
Using ZXing to create an Android barcode scanning app [duplicate]
...de reader application which — via Android's intent mechanism — can be called by other applications who wish to integrate barcode scanning.
The easiest way to do this is to call the ZXing SCAN Intent from your application, like this:
public Button.OnClickListener mScan = new Button.OnClickListe...
How to open an elevated cmd using command line for Windows?
... batch file with this and saved it as admincmd.bat in my windows folder so all I have to do is type "admincmd" hit enter and it opens an admin cmd.(I also added another line to the batch file with "exit" so it closes the non admin cmd window)
– Tony Brix
Nov 16...
Profiling Django
...at queries are executed on each page and how much time they take. It's a really useful, powerful and easy to use tool.
Also, read recommendations about Django performance in Database access optimization from the documentation.
And Django performance tips by
Jacob Kaplan-Moss.
...
Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?
...uld I use them? In which context? For what purposes?
I don't know, personally I think of it as an API design accident. Slightly forced by compound components having special ideas about child sizes. "Slightly", because they should have implemented their needs with a custom LayoutManager.
What ex...
How does !!~ (not not tilde/bang bang tilde) alter the result of a 'contains/included' Array method
...
The tilde operator isn't actually part of jQuery at all - it's a bitwise NOT operator in JavaScript itself.
See The Great Mystery of the Tilde(~).
You are getting strange numbers in your experiments because you are performing a bitwise logical operatio...
What is the difference between IEnumerator and IEnumerable? [duplicate]
... method GetEnumerator which returns an IEnumerator interface, this in turn allows readonly access to a collection. A collection that implements IEnumerable can be used with a foreach statement.
Definition
IEnumerable
public IEnumerator GetEnumerator();
IEnumerator
public object Current;
public...
What is “with (nolock)” in SQL Server?
...ly write new rows, you never update them.
– Jonathan Allen
Mar 26 '09 at 17:56
49
@Grauenwolf- An...