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What does !! mean in ruby?
...:
!!nil #=> false
!!"abc" #=> true
!!false #=> false
It's usually not necessary to use though since the only false values to Ruby are nil and false, so it's usually best to let that convention stand.
Think of it as
!(!some_val)
One thing that is it used for legitimately is preventi...
Statistics: combinations in Python
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@robertking - Ok, you were both petty and technically correct. What i did was meant as illustration of how to write one's own function; i knew it is not accurate for big enough N and K due to floating point precision. But we can fix that - see above, now it should not err f...
Faster s3 bucket duplication
...uckets without having to download and upload each file. The command I normally run to duplicate buckets using s3cmd is:
7 ...
How to crop an image using PIL?
...o the implied pixel corners; the centre of a pixel addressed as (0, 0) actually lies at (0.5, 0.5).
Coordinates are usually passed to the library as 2-tuples (x, y). Rectangles are represented as 4-tuples, with the upper left corner given first. For example, a rectangle covering all of an 800x600 p...
JPG vs. JPEG image formats
... Photographic Expert Group File Format was ‘.jpeg’; however in Windows all files required a three letter file extension. So, the file extension was shortened to ‘.jpg’. However, Macintosh was not limited to three letter file extensions, so Mac users used ‘.jpeg’. Eventually, with upgrade...
Subtract 7 days from current date
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Actually this can be done simply by: [now dateByAddingDays:-7]
– CrashOverride
Mar 5 '15 at 23:45
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MySQL dump by query
...he database by query. What he asked and what he meant were different. He really wanted to just mysqldump all tables.
mysqldump --tables myTable --where="id < 1000"
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Combating AngularJS executing controller twice
... This solved my problem of the controller being executed twice. All I did was remove the ng-controller in the template and now its only executing once.
– torbenrudgaard
May 20 '17 at 7:35
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How can I add a string to the end of each line in Vim?
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Is there a way to insert '' at the same column, since all lines are not of same length, so line 1 might have '' at 15th column, but line 2 has '*' at 25th column.
– Aman Jain
Jul 21 '10 at 20:41
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JSLint is suddenly reporting: Use the function form of “use strict”
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In JSLint for Visual Studio it's the option: "Allow global ES5 strict"
– Jowen
Oct 25 '13 at 15:07
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