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How can I add new keys to a dictionary?
...gnoring the keys
Create a dictionary from two lists
data = dict(zip(list_with_keys, list_with_values))
New to Python 3.5
Creating a merged dictionary without modifying originals:
This uses a new featrue called dictionary unpacking.
data = {**data1, **data2, **data3}
New to Python 3.9...
How to write a large buffer into a binary file in C++, fast?
...;
#include <iostream>
#include <cassert>
std::vector<uint64_t> GenerateData(std::size_t bytes)
{
assert(bytes % sizeof(uint64_t) == 0);
std::vector<uint64_t> data(bytes / sizeof(uint64_t));
std::iota(data.begin(), data.end(), 0);
std::shuffle(data.begin(), da...
Explicitly select items from a list or tuple
... myBigList[i] for i in [87, 342, 217, 998, 500] ]
20.6 usec: map(myBigList.__getitem__, (87, 342, 217, 998, 500))
22.7 usec: itemgetter(87, 342, 217, 998, 500)(myBigList)
24.6 usec: list( myBigList[i] for i in [87, 342, 217, 998, 500] )
Note that in Python 3, the 1st was changed to be the same as ...
When is “i += x” different from “i = i + x” in Python?
...
This depends entirely on the object i.
+= calls the __iadd__ method (if it exists -- falling back on __add__ if it doesn't exist) whereas + calls the __add__ method1 or the __radd__ method in a few cases2.
From an API perspective, __iadd__ is supposed to be used for modifyi...
What does multicore assembly language look like?
...els in the wild that boot from USB drives or "floppy" disks - here's an x86_32 version written in assembler using the old TSS descriptors that can actually run multi-threaded C code (github.com/duanev/oz-x86-32-asm-003) but there is no standard library support. Quite a bit more than you asked for b...
Remove all occurrences of a value from a list?
...ython 3.x
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter((2).__ne__, x))
[1, 3, 3, 4]
or
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter(lambda a: a != 2, x))
[1, 3, 3, 4]
Python 2.x
>>> x = [1,2,3,2,2,2,3,4]
>>> filter(lambda a: a != 2, x)
[1, 3, 3...
Can “list_display” in a Django ModelAdmin display attributes of ForeignKey fields?
...ion, you can do look ups like:
class UserAdmin(admin.ModelAdmin):
list_display = (..., 'get_author')
def get_author(self, obj):
return obj.book.author
get_author.short_description = 'Author'
get_author.admin_order_field = 'book__author'
...
How to duplicate sys.stdout to a log file?
...ileno())
print "\nstdout"
print >>sys.stderr, "stderr"
os.spawnve("P_WAIT", "/bin/ls", ["/bin/ls"], {})
os.execve("/bin/ls", ["/bin/ls"], os.environ)
You could also emulate tee using the multiprocessing package (or use processing if you're using Python 2.5 or earlier).
Update
Here is a Py...
Creating the Singleton design pattern in PHP5
...ctor so nobody else can instantiate it
*
*/
private function __construct()
{
}
}
To use:
$fact = UserFactory::Instance();
$fact2 = UserFactory::Instance();
$fact == $fact2;
But:
$fact = new UserFactory()
Throws an error.
See http://php.net/manual/en/language.variable...
Python string.join(list) on object array rather than string array
...
The built-in string constructor will automatically call obj.__str__:
''.join(map(str,list))
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