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What are “named tuples” in Python?
...e following:
pt1 = (1.0, 5.0)
pt2 = (2.5, 1.5)
from math import sqrt
line_length = sqrt((pt1[0]-pt2[0])**2 + (pt1[1]-pt2[1])**2)
Using a named tuple it becomes more readable:
from collections import namedtuple
Point = namedtuple('Point', 'x y')
pt1 = Point(1.0, 5.0)
pt2 = Point(2.5, 1.5)
from ...
Can someone explain __all__ in Python?
I have been using Python more and more, and I keep seeing the variable __all__ set in different __init__.py files. Can someone explain what this does?
...
How to initialize all members of an array to the same value?
...e same value, without multiple copy-paste, you can use macros:
#define VAL_1X 42
#define VAL_2X VAL_1X, VAL_1X
#define VAL_4X VAL_2X, VAL_2X
#define VAL_8X VAL_4X, VAL_4X
#define VAL_16X VAL_8X, VAL_8X
#define VAL_32X VAL_16X, VAL_16X
#define VAL_64X VAL_32X, VAL_32X
i...
Can't pickle when using multiprocessing Pool.map()
...r program to allow such methods to be pickled, registering it with the copy_reg standard library method.
For example, Steven Bethard's contribution to this thread (towards the end of the thread) shows one perfectly workable approach to allow method pickling/unpickling via copy_reg.
...
How to invoke the super constructor in Python?
...on-3.x the process has been simplified:
Python-2.x
class A(object):
def __init__(self):
print "world"
class B(A):
def __init__(self):
print "hello"
super(B, self).__init__()
Python-3.x
class A(object):
def __init__(self):
print("world")
class B(A):
def __init__(self):
print...
__FILE__ macro shows full path
The standard predefined macro __FILE__ available in C shows the full path to the file. Is there any way to short the path? I mean instead of
...
Instance attribute attribute_name defined outside __init__
.... We expect to find all the attributes an instance may have by reading its __init__ method.
You may still want to split initialization into other methods though. In such case, you can simply assign attributes to None (with a bit of documentation) in the __init__ then call the sub-initialization met...
Chaining multiple filter() in Django, is this a bug?
...el):
blog = models.ForeignKey(Blog)
headline = models.CharField(max_length=255)
pub_date = models.DateField()
...
objects
Assuming there are some blog and entry objects here.
queries
Blog.objects.filter(entry__headline_contains='Lennon',
entry__pub_date__year=2008)
Blog.object...
How do exceptions work (behind the scenes) in c++
...xception
{
public:
MyException() { }
~MyException() { }
};
void my_throwing_function(bool throwit)
{
if (throwit)
throw MyException();
}
void another_function();
void log(unsigned count);
void my_catching_function()
{
log(0);
try
{
log(1);
another_f...
Is it possible to implement a Python for range loop without an iterator variable?
...ou can just live with the extra i variable.
Here is the option to use the _ variable, which in reality, is just another variable.
for _ in range(n):
do_something()
Note that _ is assigned the last result that returned in an interactive python session:
>>> 1+2
3
>>> _
3
F...