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How to remove last n characters from every element in the R vector
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@LucasSeveryn If you want to convert character time representations to dates taking into account time zones, please edit that into your question. Likely there are better answers that will get you directly to your desired results (such as strptime).
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How to implement a many-to-many relationship in PostgreSQL?
... product (
product_id serial PRIMARY KEY -- implicit primary key constraint
, product text NOT NULL
, price numeric NOT NULL DEFAULT 0
);
CREATE TABLE bill (
bill_id serial PRIMARY KEY
, bill text NOT NULL
, billdate date NOT NULL DEFAULT CURRENT_DATE
);
CREATE TABLE bill_product...
Copy a stream to avoid “stream has already been operated upon or closed”
...low this pattern after a mapTo though using an IntStream. I found I had to convert it back to a Set<Integer> using collect(Collectors.toSet()) ... and do a couple of operations on that. I wanted max() and if a specific value was in set as two operations... filter(d -> d == -1).count() == 1;...
Cannot change column used in a foreign key constraint
...food
DROP FOREIGN KEY fk_fav_food_person_id,
MODIFY person_id SMALLINT UNSIGNED;
Now you can change you person_id
ALTER TABLE person MODIFY person_id SMALLINT UNSIGNED AUTO_INCREMENT;
recreate foreign key
ALTER TABLE favorite_food
ADD CONSTRAINT fk_fav_food_person_id FOREIGN KEY (...
Throwing the fattest people off of an overloaded airplane.
...d a MinHeap class. (Yes, my example is in C#. I think you get the idea.)
int targetTotal = 3000;
int totalWeight = 0;
// this creates an empty heap!
var myHeap = new MinHeap<Passenger>(/* need comparer here to order by weight */);
foreach (var pass in passengers)
{
if (totalWeight < t...
techniques for obscuring sensitive strings in C++
... binary, you could for instance make sure that the key is not within the printable range.
Obscuring key with XOR
For instance, you could use XOR to split the key into two byte arrays:
key = key1 XOR key2
If you create key1 with the same byte-length as key you can use (completely) random byte va...
How do browser cookie domains work?
...m will be available for example.com
Cookie with Domain=example.com will be converted to .example.com and thus will also be available for www.example.com
Cookie with Domain=example.com will not be available for anotherexample.com
www.example.com will be able to set cookie for example.com
www.example....
Is APC compatible with PHP 5.4 or PHP 5.5?
... apc isn't in svn.php.net/repository/pecl anymore. Repo has been converted to Git and can now be browsed at git.php.net/?p=pecl/caching/apc.git
– Dereckson
Oct 19 '13 at 23:47
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Assign multiple columns using := in data.table, by group
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@dnlbrky dim returns a vector so converting that to type list should rotate it; e.g. [,c("rows","cols"):=as.list(dim(get(objectName))),by=objectName]. Trouble is that as.list has call overhead and also copies the small vector. If efficiency is a proble...
Are “while(true)” loops so bad? [closed]
...gree. I was quite surprised to learn that, on my last assignment, I lost points for using a loop like the one below.
21 Ans...