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What are file descriptors, explained in simple terms?
... open a file, the operating system creates an entry to represent that file and store the information about that opened file. So if there are 100 files opened in your OS then there will be 100 entries in OS (somewhere in kernel). These entries are represented by integers like (...100, 101, 102....). ...
How to sort in-place using the merge sort algorithm?
...s the array xs, the two sorted sub-arrays are represented as ranges [i, m) and [j, n) respectively. The working area starts from w. Compare with the standard merge algorithm given in most textbooks, this one exchanges the contents between the sorted sub-array and the working area. As the result, the...
ExecJS::RuntimeError on Windows trying to follow rubytutorial
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My friend was attempting a Rails tutorial on Win 8 RTM a few months ago and ran into this error. Not sure if this issue exists in Windows 7 as well, but this may help.
Options:
1) Removing //= require_tree . / Ignoring the issue - As ColinR stated above, this line should not be causing an issue...
Drop rows with all zeros in pandas data frame
I can use pandas dropna() functionality to remove rows with some or all columns set as NA 's. Is there an equivalent function for dropping rows with all columns having value 0?
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How to use R's ellipsis feature when writing your own function?
...nts. For example, the function data.frame takes any number of arguments, and each argument becomes the data for a column in the resulting data table. Example usage:
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What is the difference between an expression and a statement in Python?
In Python, what is the difference between expressions and statements?
14 Answers
14
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How do SQL EXISTS statements work?
I'm trying to learn SQL and am having a hard time understanding EXISTS statements. I came across this quote about "exists" and don't understand something:
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Regular expression that matches valid IPv6 addresses
...ular expressions, so I wrote one that works with POSIX regular expressions and PERL regular expressions.
It should match:
IPv6 addresses
zero compressed IPv6 addresses (section 2.2 of rfc5952)
link-local IPv6 addresses with zone index (section 11 of rfc4007)
IPv4-Embedded IPv6 Address (section 2 ...
Listing each branch and its last revision's date in Git
I need to delete old and unmaintained branches from our remote repository. I'm trying to find a way with which to list the remote branches by their last modified date, and I can't.
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What's the difference between --general-numeric-sort and --numeric-sort options in gnu sort
...mbers as floats, this allows scientific notation eg 1.234E10 but is slower and subject to rounding error (1.2345678 could come after 1.2345679), numeric sort is just a regular alphabetic sort that knows 10 comes after 9.
See http://www.gnu.org/software/coreutils/manual/html_node/sort-invocatio...