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How to use a variable to specify column name in ggplot

... If for whatever reason you'd rather not use aes_string, you could change it to (the somewhat more cumbersome): ggplot( rates.by.groups, aes(x=name, y=rate, colour= get(column), group=get(column) ) ) ...
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Can an abstract class have a constructor?

...n the parent abstract class, the constructor used in subclass must explicitly call the parent constructor. share | improve this answer | follow | ...
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Is embedding background image data into CSS as Base64 good or bad practice?

... It's not a good idea when you want your images and style information to be cached separately. Also if you encode a large image or a significant number of images in to your css file it will take the browser longer to download...
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How does a hash table work?

...xplanation in layman's terms. Let's assume you want to fill up a library with books and not just stuff them in there, but you want to be able to easily find them again when you need them. So, you decide that if the person that wants to read a book knows the title of the book and the exact title to...
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How to list the files inside a JAR file?

...e == null) break; String name = e.getName(); if (name.startsWith("path/to/your/dir/")) { /* Do something with this entry. */ ... } } } else { /* Fail... */ } Note that in Java 7, you can create a FileSystem from the JAR (zip) file, and then use NIO's directory wa...
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Do HTML WebSockets maintain an open connection for each client? Does this scale?

I am curious if anyone has any information about the scalability of HTML WebSockets. For everything I've read it appears that every client will maintain an open line of communication with the server. I'm just wondering how that scales and how many open WebSocket connections a server can handle. Mayb...
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Change Name of Import in Java, or import two classes with the same name

...re is no import aliasing mechanism in Java. You cannot import two classes with the same name and use both of them unqualified. Import one class and use the fully qualified name for the other one, i.e. import com.text.Formatter; private Formatter textFormatter; private com.json.Formatter jsonForma...
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NVIDIA vs AMD: GPGPU performance

I'd like to hear from people with experience of coding for both. Myself, I only have experience with NVIDIA. 10 Answers ...
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How do I detect that an iOS app is running on a jailbroken phone?

... It depends what you mean by jailbreak. In the simple case, you should be able to see if Cydia is installed and go by that - something like NSString *filePath = @"/Applications/Cydia.app"; if ([[NSFileManager defaultManager]...
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Best approach to real time http streaming to HTML5 video client

... EDIT 3: As of IOS 10, HLS will support fragmented mp4 files. The answer now, is to create fragmented mp4 assets, with a DASH and HLS manifest. > Pretend flash, iOS9 and below and IE 10 and below don't exist. Everything b...