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How to pull a random record using Django's ORM?
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count = self.aggregate(count=Count('id'))['count']
random_index = randint(0, count - 1)
return self.all()[random_index]
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Most efficient way to check for DBNull and then assign to a variable?
...ional example, no - it really shouldn't (and doesn't). It will execute the indexer twice.
– Marc Gravell♦
Oct 21 '08 at 12:06
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What is copy-on-write?
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I found this good article about zval in PHP, which mentioned COW too:
Copy On Write (abbreviated as ‘COW’) is a trick designed to save memory. It is used more generally in software engineering. It means that PHP will copy the memory (or allocate new memory ...
Configuring Vim for C++
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NERDTree http://www.vim.org/scripts/script.php?script_id=1658
Exuberant ctags (vim already supports the hotkeys natively) http://ctags.sourceforge.net/
taglist: http://vim-taglist.sourceforge.net/
snipmate: http://www.vim.org/scripts/script.php?script_id=2540
I do...
Convert light frequency to RGB?
..._MAX)
return new byte[3];
len -= LEN_MIN;
var index = (int)Math.Floor(len / LEN_STEP);
var offset = len - LEN_STEP * index;
var x = Interpolate(X, index, offset);
var y = Interpolate(Y, index, offset);
var z = Interpolate(Z, index, offset...
Picking a random element from a set
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Fast solution for Java using an ArrayList and a HashMap: [element -> index].
Motivation: I needed a set of items with RandomAccess properties, especially to pick a random item from the set (see pollRandom method). Random navigation in a binary tree is not accurate: trees are not perfectly bal...
Keep ignored files out of git status
...or untracked files. If you added files to repository, you can:
git update-index --assume-unchanged <file>
or remove them from repository by
git rm --cached <file>
Edit
This article explains that too
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UICollectionView current visible cell index
...tionViewCell *cell in [self.mainImageCollection visibleCells]) {
NSIndexPath *indexPath = [self.mainImageCollection indexPathForCell:cell];
NSLog(@"%@",indexPath);
}
}
Update to Swift 5:
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
for cell in yourCollec...
Storing R.drawable IDs in XML array
...tResources().obtainTypedArray(R.array.random_imgs);
// get resource ID by index
imgs.getResourceId(i, -1)
// or set you ImageView's resource to the id
mImgView1.setImageResource(imgs.getResourceId(i, -1));
// recycle the array
imgs.recycle();
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What are the benefits of Java's types erasure?
...ing. This is not to say that testing is intrinsically a bad idea, but the quoted Twitter user is suggesting that there is a much better way.
So our goal is to have correct programs that we can reason about clearly and rigorously in a way that corresponds with how the machine will actually execute t...