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Extract a regular expression match
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Use the new stringr package which wraps all the existing regular expression operates in a consistent syntax and adds a few that are missing:
library(stringr)
str_locate("aaa12xxx", "[0-9]+")
# start end
# [1,] 4 5
str_extract("aaa12xxx", "[0-9]+")
# [1]...
Difference between Covariance & Contra-variance
...ng function that associates one member of a set with another. More specifically, a mapping can be covariant or contravariant with respect to a relation on that set.
Consider the following two subsets of the set of all C# types. First:
{ Animal,
Tiger,
Fruit,
Banana }.
And second, this c...
Why do I need to override the equals and hashCode methods in Java?
...hich will prevent your class from functioning properly in conjunction with all hash-based collections, including HashMap, HashSet, and Hashtable.
Let's try to understand it with an example of what would happen if we override equals() without overriding hashCode() and attempt to use a Map.
Say we ha...
How can I resize an image using Java?
...source libraries to see if they fare better. " +1 for imgscalr from @RiyadKalla's answer.
– Thilo
Aug 24 '12 at 1:29
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show 1 more comment
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How to suppress Java warnings for specific directories or files such as generated code
...t; Source
Announced here: Eclipse 3.8 and 4.2 M6 - New and Noteworthy, called Selectively ignore errors/warnings from source folders. That's also where the screenshot is from. This is the new feature developed on the previously linked Bug 220928.
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Convert Existing Eclipse Project to Maven Project
...atic importer or wizard?': not that I know of. Using the option above will allow you to enable the m2eclipse plugin for your existing project avoiding the manual copying. You will still need to actually set up the dependencies and other stuff you need to build yourself.
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ExecuteReader requires an open and available Connection. The connection's current state is Connectin
...n the Connection-Pool's territory
There's a good reason why ADO.NET internally manages the underlying Connections to the DBMS in the ADO-NET Connection-Pool:
In practice, most applications use only one or a few different
configurations for connections. This means that during application
exe...
R memory management / cannot allocate vector of size n Mb
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Consider whether you really need all this data explicitly, or can the matrix be sparse? There is good support in R (see Matrix package for e.g.) for sparse matrices.
Keep all other processes and objects in R to a minimum when you need to make obj...
How to generate a number of most distinctive colors in R?
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I joined all qualitative palettes from RColorBrewer package. Qualitative palettes are supposed to provide X most distinctive colours each. Of course, mixing them joins into one palette also similar colours, but that's the best I can g...
What is the difference between a symbolic link and a hard link?
... (Or is it multiple inodes? Not sure.)
A file in the file system is basically a link to an inode.
A hard link, then, just creates another file with a link to the same underlying inode.
When you delete a file, it removes one link to the underlying inode. The inode is only deleted (or deletable/ove...