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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,...
What is the difference between return and return()?
I tested the above code in Chrome's console, and both returned 1 .
9 Answers
9
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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...
CPU Privilege Rings: Why rings 1 and 2 aren't used?
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114
As a hobbyist operating system writer, I found that because paging (a major part of the modern...
How does one reorder columns in a data frame?
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11 Answers
11
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Why does this assert throw a format exception when comparing structures?
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100
I've got it. And yes, it's a bug.
The problem is that there are two levels of string.Format g...
How can we make xkcd style graphs?
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edited May 17 '13 at 9:57
answered May 16 '13 at 20:49
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WAMP 403 Forbidden message on Windows 7
I have installed WAMP version 2.1 on my windows 7 machine. When i browse to localhost in my browser, the WAMP server page is visible.
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