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How to swap keys and values in a hash
...was inverted (in essence, by letting you access keys through values):
{a: 1, b: 2, c: 3}.key(1)
=> :a
If you want to keep the inverted hash, then Hash#invert should work for most situations:
{a: 1, b: 2, c: 3}.invert
=> {1=>:a, 2=>:b, 3=>:c}
BUT...
If you have duplicate values,...
How can I add a help method to a shell script?
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here's an example for bash:
usage="$(basename "$0") [-h] [-s n] -- program to calculate the an...
Why does Eclipse complain about @Override on interface methods?
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How to find the JVM version from a program?
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What is the difference between return and return()?
I tested the above code in Chrome's console, and both returned 1 .
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quick random row selection in Postgres
...ith OFFSET, as in
SELECT myid FROM mytable OFFSET floor(random()*N) LIMIT 1;
The N is the number of rows in mytable. You may need to first do a SELECT COUNT(*) to figure out the value of N.
Update (by Antony Hatchkins)
You must use floor here:
SELECT myid FROM mytable OFFSET floor(random()*N) L...
How to remove the left part of a string?
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answered Apr 25 at 21:01
Xavier GuihotXavier Guihot
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CPU Privilege Rings: Why rings 1 and 2 aren't used?
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As a hobbyist operating system writer, I found that because paging (a major part of the modern...
Convert base-2 binary number string to int
...e base of the input number, i.e. 2 for a binary number:
>>> int('11111111', 2)
255
Here is documentation for python2, and for python3.
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