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Preventing Laravel adding multiple records to a pivot table
...ng record by writing a very simple condition like this one :
if (! $cart->items->contains($newItem->id)) {
$cart->items()->save($newItem);
}
Or/and you can add unicity condition in your database, it would throw an exception during an attempt of saving a doublet.
You should als...
PHP's array_map including keys
... doesn't handle keys.
array_walk does:
$test_array = array("first_key" => "first_value",
"second_key" => "second_value");
array_walk($test_array, function(&$a, $b) { $a = "$b loves $a"; });
var_dump($test_array);
// array(2) {
// ["first_key"]=>
// string(27) ...
Converting a list to a set changes element order
...erving the order of the list, you can do this with a list comprehension:
>>> a = [1, 2, 20, 6, 210]
>>> b = set([6, 20, 1])
>>> [x for x in a if x not in b]
[2, 210]
If you need a data structure that supports both fast membership tests and preservation of insertion orde...
Explicitly set Id with Doctrine when using “AUTO” strategy
...ence based.
I've to add this line to make it work perfectly :
$metadata->setIdGenerator(new \Doctrine\ORM\Id\AssignedGenerator());
Best regards,
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What is the easiest way to remove the first character from a string?
...or using something like:
asdf = "[12,23,987,43"
asdf[0] = ''
p asdf
# >> "12,23,987,43"
I'm always looking for the fastest and most readable way of doing things:
require 'benchmark'
N = 1_000_000
puts RUBY_VERSION
STR = "[12,23,987,43"
Benchmark.bm(7) do |b|
b.report('[0]') { N....
Python str vs unicode types
... type for a plain sequence of bytes.
Some differences that you can see:
>>> len(u'à') # a single code point
1
>>> len('à') # by default utf-8 -> takes two bytes
2
>>> len(u'à'.encode('utf-8'))
2
>>> len(u'à'.encode('latin1')) # in latin1 it takes one ...
What's the idiomatic syntax for prepending to a short python list?
...ray and move everything down by one for every insertion:
for (i = n; --i >= where; )
items[i+1] = items[i];
If you want a container/list that's efficient at prepending elements, you want a linked list. Python has a doubly linked list, which can insert at the beginning and end quickly - it'...
Why do we need tuples in Python (or any immutable data type)?
...f mutable objects can change, but that's a hidden implementation detail.
>>> x='hello'
>>> id(x)
1234567
>>> x='good bye'
>>> id(x)
5432167
This isn't modifying ("mutating") the variable; it's creating a new variable with the same name, and discarding the old o...
How do I get the number of elements in a list?
...nt types in Python - both built-in types and library types. For example:
>>> len([1,2,3])
3
Official 2.x documentation is here: len()
Official 3.x documentation is here: len()
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im...
How to do exponential and logarithmic curve fitting in Python? I found only polynomial fitting
...
For fitting y = A + B log x, just fit y against (log x).
>>> x = numpy.array([1, 7, 20, 50, 79])
>>> y = numpy.array([10, 19, 30, 35, 51])
>>> numpy.polyfit(numpy.log(x), y, 1)
array([ 8.46295607, 6.61867463])
# y ≈ 8.46 log(x) + 6.62
For fitting y ...