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How to choose an AES encryption mode (CBC ECB CTR OCB CFB)?
...not decryption, which can save code space.
CTR is used if you want good parallelization (ie. speed), instead of CBC/OFB/CFB.
XTS mode is the most common if you are encoding a random accessible data (like a hard disk or RAM).
OCB is by far the best mode, as it allows encryption and authentication in ...
Blocks and yields in Ruby
...trary segments of code.
When a method expects a block, it invokes it by calling the yield function.
This is very handy, for instance, to iterate over a list or to provide a custom algorithm.
Take the following example:
I'm going to define a Person class initialized with a name, and provide a ...
How to create JSON string in JavaScript?
... create JSON string just to play around. It's throwing error, but if I put all the name, age, married in one single line (line 2) it doesn't. Whats the problem?
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Get statistics for each group (such as count, mean, etc) using pandas GroupBy?
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What if I have a separate called Counts and instead of count the rows of the grouped type, I need to add along the column Counts.
– Abhishek Bhatia
Oct 2 '17 at 21:28
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How to un-escape a backslash-escaped string?
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Basically for Python3 you want print(b"Hello,\nworld!".decode('unicode_escape'))
– ChristopheD
Apr 7 '15 at 8:35
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How do I delete a fixed number of rows with sorting in PostgreSQL?
...erm row identifier.
There's also oid but that only exists if you specifically ask for it when you create the table.
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Add new attribute (element) to JSON object using JavaScript
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JSON stands for JavaScript Object Notation. A JSON object is really a string that has yet to be turned into the object it represents.
To add a property to an existing object in JS you could do the following.
object["property"] = value;
or
object.property = value;
If you provide ...
How to add an auto-incrementing primary key to an existing table, in PostgreSQL?
...of PostgreSQL
In old versions of PostgreSQL (prior to 8.x?) you had to do all the dirty work. The following sequence of commands should do the trick:
ALTER TABLE test1 ADD COLUMN id INTEGER;
CREATE SEQUENCE test_id_seq OWNED BY test1.id;
ALTER TABLE test ALTER COLUMN id SET DEFAULT nextval('...
What is the effect of encoding an image in base64?
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Here's a really helpful overview of when to base64 encode and when not to by David Calhoun.
Basic answer = gzipped base64 encoded files will be roughly comparable in file size to standard binary (jpg/png). Gzip'd binary files will ha...
Blank HTML SELECT without blank item in dropdown list
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Actually IE 11 does display the "hidden" option.
– Edward Olamisan
Oct 15 '13 at 18:47
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