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Approximate cost to access various caches and main memory?
Can anyone give me the approximate time (in nanoseconds) to access L1, L2 and L3 caches, as well as main memory on Intel i7 processors?
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What does the “at” (@) symbol do in Python?
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An @ symbol at the beginning of a line is used for class, function and method decorators.
Read more here:
PEP 318: Decorators
Python Decorators
The most common Python decorators you'll run into are:
@property
@classmethod
@staticmethod
If you see an @ in the middle of a line, that's ...
Difference between a theta join, equijoin and natural join
I'm having trouble understanding relational algebra when it comes to theta joins, equijoins and natural joins. Could someone please help me better understand it? If I use the = sign on a theta join is it exactly the same as just using a natural join?
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Split data frame string column into multiple columns
... stringr::str_split_fixed
library(stringr)
str_split_fixed(before$type, "_and_", 2)
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print call stack in C or C++
... option. Note that names of "static" functions are not exposed,
and won't be
available in the backtrace.
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Accessing dict keys like an attribute?
... Unless - of course - you assign some value to them, see below)
Attributes and items are always in sync
Trying to access non-existent key as an attribute correctly raises AttributeError instead of KeyError
Supports [Tab] autocompletion (e.g. in jupyter & ipython)
Cons:
Methods like .keys() wil...
Is arr.__len__() the preferred way to get the length of an array in Python?
...5
The same works for tuples:
my_tuple = (1,2,3,4,5)
len(my_tuple)
# 5
And strings, which are really just arrays of characters:
my_string = 'hello world'
len(my_string)
# 11
It was intentionally done this way so that lists, tuples and other container types or iterables didn't all need to expl...
A python class that acts like dict
...ict actually contains 2 dict-instance: The 1st is the inherited container, and the 2nd is the dict holding the class-attributes - you may avoid that by using slots.
– ankostis
Mar 4 '16 at 10:37
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Differences between lodash and underscore [closed]
...nsistent cross-environment iteration support for arrays, strings, objects, and arguments objects1. It has since become a superset of Underscore, providing more consistent API behavior, more features (like AMD support, deep clone, and deep merge), more thorough documentation and unit tests (tests whi...
Why does the expression 0 < 0 == 0 return False in Python?
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I believe Python has special case handling for sequences of relational operators to make range comparisons easy to express. It's much nicer to be able to say 0 < x <= 5 than to say (0 < x) and (x <= 5).
These are called chained comparisons. And th...