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Quickly reading very large tables as dataframes
... very large tables (30 million rows) that I would like to load as a dataframes in R. read.table() has a lot of convenient features, but it seems like there is a lot of logic in the implementation that would slow things down. In my case, I am assuming I know the types of the columns ahead of time...
Does use of final keyword in Java improve the performance?
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Usually not. For virtual methods, HotSpot keeps track of whether the method has actually been overridden, and is able to perform optimizations such as inlining on the assumption that a method hasn't been overridden - until it loads a class which over...
How do I create a nice-looking DMG for Mac OS X using command-line tools?
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After lots of research, I've come up with this answer, and I'm hereby putting it here as an answer for my own question, for reference:
Make sure that "Enable access for assistive devices" is checked in System Preferences>>Universal Access. It is re...
Converting an array of objects to ActiveRecord::Relation
...ay of objects, let's call it an Indicator . I want to run Indicator class methods (those of the def self.subjects variety, scopes, etc) on this array. The only way I know to run class methods on a group of objects is to have them be an ActiveRecord::Relation. So I end up resorting to adding a to...
Is it possible to decrypt MD5 hashes?
Someone told me that he has seen software systems that:
24 Answers
24
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How to show all privileges from a user in oracle?
Can someone please tell me how to show all privileges/rules from a specific user in the sql-console?
6 Answers
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Multiple aggregations of the same column using pandas GroupBy.agg()
...uilt-in way to apply two different aggregating functions f1, f2 to the same column df["returns"] , without having to call agg() multiple times?
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Is there a way to instantiate objects from a string holding their class name?
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Nope, there is none, unless you do the mapping yourself. C++ has no mechanism to create objects whose types are determined at runtime. You can use a map to do that mapping yourself, though:
template<typename T> Base * createInstance() { return new T; }
typedef std::map<std::string,...
Does setting Java objects to null do anything anymore?
I was browsing some old books and found a copy of "Practical Java" by Peter Hagger. In the performance section, there is a recommendation to set object references to null when no longer needed.
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How can I build a small operating system on an old desktop computer? [closed]
... have a firm understanding of how the OS works before you can hope to implement your own.
Grab one of Andrew Tanenbaum's books on operating systems. This is the one we used in my OS class in college:
Modern Operating Systems PDF
Modern Operating Systems on Amazon
Despite the ridiculous cov...