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Reorder levels of a factor without changing order of values
I have data frame with some numerical variables and some categorical factor variables. The order of levels for those factors is not the way I want them to be.
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valueOf() vs. toString() in Javascript
In Javascript every object has a valueOf() and toString() method. I would have thought that the toString() method got invoked whenever a string conversion is called for, but apparently it is trumped by valueOf().
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MySQL: @variable vs. variable. What's the difference?
...are loosely typed variables that may be initialized somewhere in a session and keep their value until the session ends.
They are prepended with an @ sign, like this: @var
You can initialize this variable with a SET statement or inside a query:
SET @var = 1
SELECT @var2 := 2
When you develop a stor...
ITunes review URL and iOS 7 (ask user to rate our app) AppStore show a blank page
Does anybody knows if the technique used to ask the user to rate our app and open for him the App Store directly on the rating page is still working on iOS 7 ?
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Android Studio installation on Windows 7 fails, no JDK found
I downloaded Android Studio and attempted to launch the program.
29 Answers
29
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What is the difference between “JPG” / “JPEG” / “PNG” / “BMP” / “GIF” / “TIFF” Image?
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Yes. They are different file formats (and their file extensions).
Wikipedia entries for each of the formats will give you quite a bit of information:
JPEG (or JPG, for the file extension; Joint Photographic Experts Group)
PNG (Portable Network Graphics)
BMP (B...
Convert RGB to RGBA over white
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Take the lowest color component, and convert that to an alpha value. Then scale the color components by subtracting the lowest, and dividing by the alpha value.
Example:
152 converts to an alpha value of (255 - 152) / 255 ~ 0.404
152 scales using (152 - 1...
How to check if a table exists in a given schema
Postgres 8.4 and greater databases contain common tables in public schema and company specific tables in company schema.
company schema names always start with 'company' and end with the company number.
So there may be schemas like:
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Why would you use an ivar?
...is question asked the other way, such as Must every ivar be a property? (and I like bbum's answer to this Q).
7 Answers
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Making WPF applications look Metro-styled, even in Windows 7? (Window Chrome / Theming / Theme)
I like the window chrome on the new Office Suite and Visual Studio:
6 Answers
6
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