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Reverse / invert a dictionary mapping
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For Python 2.7.x
inv_map = {v: k for k, v in my_map.iteritems()}
For Python 3+:
inv_map = {v: k for k, v in my_map.items()}
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Age from birthdate in python
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That probably depends on your definition of "age". For all practical purposes a birthday is usually given as a date, not timezone-aware datetime (i.e., "born" is missing the details). Most people are not born at midnight sharp (so usually observe prematurely :-)), and when in a d...
@ variables in Ruby on Rails
...cope (current block)
@title is an instance variable - and is available to all methods within the class.
You can read more here:
http://strugglingwithruby.blogspot.dk/2010/03/variables.html
In Ruby on Rails - declaring your variables in your controller as instance variables (@title) makes them ava...
Grab a segment of an array in Java without creating a new array on heap
...wer by @unique72 is correct. Imma let this edit sit for a bit and then I shall delete this answer.)
I don't know of a way to do this directly with arrays without additional heap allocation, but the other answers using a sub-list wrapper have additional allocation for the wrapper only – but not...
Double Negation in C++
...ernel). For GCC, they're implemented as follows:
#define likely(cond) (__builtin_expect(!!(cond), 1))
#define unlikely(cond) (__builtin_expect(!!(cond), 0))
Why do they have to do this? GCC's __builtin_expect treats its parameters as long and not bool, so there needs to be some form of conver...
How can I run a PHP script in the background after a form is submitted?
...f subscribers and send out 150+ emails. (The emails are being sent individually as requested by the system administrators of our email server because of mass email policies.)
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How to close current tab in a browser window?
...ndow.close();
or you can specify a different window.
So:
function close_window() {
if (confirm("Close Window?")) {
close();
}
}
with HTML:
<a href="javascript:close_window();">close</a>
or:
<a href="#" onclick="close_window();return false;">close</a>
You r...
What is the difference between UTF-8 and ISO-8859-1?
...e points of the Unicode character set, whereas UTF-8 can be used to encode all code points. At physical encoding level, only codepoints 0 - 127 get encoded identically; code points 128 - 255 differ by becoming 2-byte sequence with UTF-8 whereas they are single bytes with Latin-1.
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How to hash a password
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I would REALLY recommend using SHA1. MD5 is a no-no unless you are maintaining backward compatibility with an existing system. In addition, make sure you put it in a using statement or call Clear() on it when you are done using the imp...
How do I write a correct micro-benchmark in Java?
...istics.
Rule 1: Always include a warmup phase which runs your test kernel all the way through, enough to trigger all initializations and compilations before timing phase(s). (Fewer iterations is OK on the warmup phase. The rule of thumb is several tens of thousands of inner loop iterations.)
Rule ...