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Build tree array from flat array in javascript
... below )
Here it is:
const createDataTree = dataset => {
let hashTable = Object.create(null)
dataset.forEach( aData => hashTable[aData.ID] = { ...aData, childNodes : [] } )
let dataTree = []
dataset.forEach( aData => {
if( aData.parentID ) hashTable[aData.parentID]....
Why should C++ programmers minimize use of 'new'?
...omposes. It scales.
If you use the Line class as a building block:
class Table
{
Line borders[4];
};
Then
int main ()
{
Table table;
}
allocates four std::string instances, four Line instances, one Table instance and all the string's contents and everything is freed automagically...
Undo scaffolding in Rails
...e db:rollback before you destroy your scaffold. This will destroy/drop the table if there is no other migration except the scaffold's migration before it.
– Yakob Ubaidi
May 8 '14 at 11:06
...
Java: Detect duplicates in ArrayList?
...anding your question correctly, you have a 2d array of Block, as in
Block table[][];
and you want to detect if any row of them has duplicates?
In that case, I could do the following, assuming that Block implements "equals" and "hashCode" correctly:
for (Block[] row : table) {
Set set = new Ha...
MySQL and GROUP_CONCAT() maximum length
...T SESSION group_concat_max_len = 1000000;
select group_concat(column) from table group by column
You can do this even in sharing hosting, but when you use an other session, you need to repeat the SET SESSION command.
share...
Find a pair of elements from an array whose sum equals a given number
...r=[1,2,1,2,1,2,1,...]. For uniqueness by value, it seems like another hash table keyed by a value-pair would do the trick. Still a nice, compact, elegant answer. +1
– William
Feb 10 '11 at 18:49
...
How do I monitor the computer's CPU, memory, and disk usage in Java?
...GAR API in one of my own applications and it is great. You'll find it is stable, well supported, and full of useful examples. It is open-source with a GPL 2 Apache 2.0 license. Check it out. I have a feeling it will meet your needs.
Using Java and the Sigar API you can get Memory, CPU, Disk, Lo...
Make body have 100% of the browser height
...the best solution:
html {
width: 100%;
height: 100%;
display: table;
}
body {
width: 100%;
display: table-cell;
}
html, body {
margin: 0px;
padding: 0px;
}
It is dynamic in that the html and the body elements will expand automatically if their contents overflow. I t...
Export to CSV via PHP
... // return you own sql
$sql = "SELECT id, date, params, value FROM sometable ORDER BY date;";
return $sql;
}
function getExportData()
{
$values = array();
$sql = $this->getSql();
if (strlen($sql) > 0)
{
$result = dbquery($sql); // opens the database and execut...
HashSet vs. List performance
...lly a collection in the .NET framework that switches between a list and hastable implementation depending on the number of items it contains: HybridDictionary.
– MgSam
Nov 1 '13 at 2:12
...