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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...
Rails where condition using NOT NIL
...udes(:bar).where.not(bars: { id: nil })
When working with scopes between tables, I prefer to leverage merge so that I can use existing scopes more easily.
Foo.includes(:bar).merge(Bar.where.not(id: nil))
Also, since includes does not always choose a join strategy, you should use references here...
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...
How to get distinct values for non-key column fields in Laravel?
...should use groupby. In Query Builder you can do it this way:
$users = DB::table('users')
->select('id','name', 'email')
->groupBy('name')
->get();
share
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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
...
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
...
Compute a confidence interval from sample data
... Careful with the "private" use of sp.stats.t._ppf. I'm not that comfortable with that in there without further explanation. Better to use sp.stats.t.ppf directly, unless you are sure you know what you are doing. On quick inspection of the source there is a fair amount of code skipped with _pp...
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...
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...
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
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