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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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count(*) vs count(column-name) - which is more correct? [duplicate]
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What about count( col ) where col is a primary indexed column ? I thaught indexes help making tasks faster ?
– Stphane
Aug 28 '15 at 13:47
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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...
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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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...
CSS Background Opacity [duplicate]
...lt;/article>
Then apply some CSS
article {
position: relative;
z-index: 1;
}
article::before {
content: "";
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
opacity: .4;
z-index: -1;
background: url(path/to/your/image);
}
Sample: http://codepen.io/a...
Python loop that also accesses previous and next values
...o the trick.
foo = somevalue
previous = next_ = None
l = len(objects)
for index, obj in enumerate(objects):
if obj == foo:
if index > 0:
previous = objects[index - 1]
if index < (l - 1):
next_ = objects[index + 1]
Here's the docs on the enumerate ...
Convert a list to a dictionary in Python
...or this pretty easily:
a = ['hello','world','1','2']
my_dict = {item : a[index+1] for index, item in enumerate(a) if index % 2 == 0}
This is equivalent to the for loop below:
my_dict = {}
for index, item in enumerate(a):
if index % 2 == 0:
my_dict[item] = a[index+1]
...