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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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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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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...
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...
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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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...
Serializing class instance to JSON
I am trying to create a JSON string representation of a class instance and having difficulty. Let's say the class is built like this:
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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...
unique object identifier in javascript
I need to do some experiment and I need to know some kind of unique identifier for objects in javascript, so I can see if they are the same. I don't want to use equality operators, I need something like the id() function in python.
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Object of custom type as dictionary key
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You need to add 2 methods, note __hash__ and __eq__:
class MyThing:
def __init__(self,name,location,length):
self.name = name
self.location = location
self.length = length
def __hash__(self):
return hash((self.name, self.lo...