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What's the fastest way to merge/join data.frames in R?
...he first. If there are duplicates in the second data frame then the match and merge approaches are not the same. Match is, of course, faster since it is not doing as much. In particular it never looks for duplicate keys. (continued after code)
DF1 = data.frame(a = c(1, 1, 2, 2), b = 1:4)
DF2 = da...
What's the difference between design patterns and architectural patterns?
...ou find in programs. It allows us to deconstruct a large complex structure and build using simple parts. It provides a general solution for a class of problems.
A large complex software goes through a series of deconstruction at different levels. At large level, architectural patterns are the tool...
Android Studio with Google Play Services
I'm trying to test Google Play Services with the new Android Studio.
I have a project with a dependency to the google_play_services.jar.
But when I try to Rebuild the project I get the following errors:
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What does SynchronizationContext do?
...alling the static SynchronizationContext.SetSynchronizationContext method, and the current context of the running thread can be queried via the SynchronizationContext.Current property.
Despite what I just wrote (each thread having an associated synchronization context), a SynchronizationContext does...
Should I use px or rem value units in my CSS? [closed]
I am designing a new website and I want it to be compatible with as much browsers and browser settings as possible. I am trying to decide what unit of measurement I should use for the sizes of my fonts and elements, but am unable to find a conclusive answer.
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Detect encoding and make everything UTF-8
I'm reading out lots of texts from various RSS feeds and inserting them into my database.
24 Answers
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Need for predictable random generator
I'm a web-game developer and I got a problem with random numbers. Let's say that a player has 20% chance to get a critical hit with his sword. That means, 1 out of 5 hits should be critical. The problem is I got very bad real life results — sometimes players get 3 crits in 5 hits, sometimes none i...
What are the differences between a HashMap and a Hashtable in Java?
What are the differences between a HashMap and a Hashtable in Java?
35 Answers
35
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Do I really have a car in my garage? [duplicate]
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If you need to make the difference between Car and Boat in your garage, then you should store them in distinct structures.
For instance:
public class Garage {
private List<Car> cars;
private List<Boat> boats;
}
Then you can define methods that are ...
Python executable not finding libpython shared library
I am installing Python 2.7 on CentOS 5. I built and installed Python as follows
9 Answers
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