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Assign multiple columns using := in data.table, by group
What is the best way to assign to multiple columns using data.table ? For example:
2 Answers
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User recognition without cookies or local storage
... $totalRun = 0;
$yin = 0;
// Trains RNA until it gets stable
while ($keepTrainning == true) {
// Sweeps each row of the input subject
foreach ($input as $row_counter => $row_data) {
// Finds out the number of columns the input ha...
Create unique constraint with null columns
I have a table with this layout:
4 Answers
4
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Generate GUID in MySQL for existing Data?
I've just imported a bunch of data to a MySQL table and I have a column "GUID" that I want to basically fill down all existing rows with new and unique random GUID's.
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How do I get the last inserted ID of a MySQL table in PHP?
I have a table into which new data is frequently inserted. I need to get the very last ID of the table. How can I do this?
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What are the typical reasons Javascript developed on Firefox fails on IE? [closed]
...pport setting the innerHTML of col, colGroup, frameSet, html, head, style, table, tBody, tFoot, tHead, title, and tr elements. Here's a function which works around that for table-related elements:
function setHTML(elm, html) {
// Try innerHTML first
try {
elm.innerHTML = html;
} catch (exc) {
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php is null or empty?
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As is shown in the following table, empty($foo) is equivalent to $foo==null and is_null($foo) has the same function of $foo===null. The table also shows some tricky values regarding the null comparison. (ϕ denotes an uninitialized variables. )
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How does a PreparedStatement avoid or prevent SQL injection?
...);
If "user" came from user input and the user input was
Robert'); DROP TABLE students; --
Then in the first instance, you'd be hosed. In the second, you'd be safe and Little Bobby Tables would be registered for your school.
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Spring @Transactional - isolation, propagation
...tted: Allows dirty reads.
Read Committed: Does not allow dirty reads.
Repeatable Read: If a row is read twice in the same transaction, the result will always be the same.
Serializable: Performs all transactions in a sequence.
The different levels have different performance characteristics in a mul...
Any way to declare a size/partial border to a box?
...g...
Partly underlined text elements can easily achieved by using display:table or display:inline-block
(I just don't use display:inline-block because, yeah you know, the awkward 4px-gap).
Textual Elements
h1 {
border-bottom: 1px solid #f00;
display: table;
}
<h1>Foo is not equ...