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List of Big-O for PHP functions
...all: Thanks! I did a bit of reading and it turns out PHP uses 'nested' hashtables for collisions. That is, instead of a logn structure for collisions it simply uses another hashtable. And I do understand that practically speaking PHP hashtables give O(1) performance, or at least O(1) on average - t...
Is it possible to modify variable in python that is in outer, but not global, scope?
...esides the global
(module) scope.
For python 2, I usually just use a mutable object (like a list, or dict), and mutate the value instead of reassign.
example:
def foo():
a = []
def bar():
a.append(1)
bar()
bar()
print a
foo()
Outputs:
[1, 1]
...
Is null an Object?
...y hands with »Big Apple« (=reference type name) written on it.
There's a table (=heap) in front of me.
If there is an apple (=instance) on the table there is a cord (=reference) connected to it.
I hold the other end of this cord in my hand (=reference variable) .
I trace the apple along the cord...
What is the Java string pool and how is “s” different from new String(“s”)? [duplicate]
...storing only one copy
of each distinct string value, which
must be immutable. Interning strings
makes some string processing tasks
more time- or space-efficient at the
cost of requiring more time when the
string is created or interned. The
distinct values are stored in a string
inter...
C++ performance challenge: integer to std::string conversion
... first one is a fun implementation that doesn't use any precomputed lookup tables or explicit division/modulo. This one is competitive with the others with gcc and with all but Timo's on msvc (for a good reason that I explain below). The second algorithm is my actual submission for highest performan...
How to do associative array/hashing in JavaScript
...ash/AS3 Dictionary does. In JavaScript, var obj1 = {}; var obj2 = {}; var table= {}; table[obj1] = "A"; table[obj2] = "B"; alert(table[obj1]); //displays B, because it can't differentiate between keys obj1 and obj2; they're both converted to string and just become something like "Object". Total fa...
What’s the difference between ScalaTest and Scala Specs unit test frameworks?
...
Mockito has been given a nice BDD support in specs: Mockito
specs has DataTables which allow to group a lot of small example in a sort of table (if you can stand operators being used as the table delimiters)
In specs, you can define examples which are nested as libidum and automatically cleaned-up ...
How to store a dataframe using Pandas
...and read_pickle respectively).
Another popular choice is to use HDF5 (pytables) which offers very fast access times for large datasets:
store = HDFStore('store.h5')
store['df'] = df # save it
store['df'] # load it
More advanced strategies are discussed in the cookbook.
Since 0.13 there's...
SQL Server IN vs. EXISTS Performance
... test case does not mean that the optimizer will do the exact same plan on tables with different statistics. This might lead someone to think the answer is partial - but the nonexistence of multiple semijoin operators is fact. Maybe I'll find a list somewhere and link it.
– Geo...
How to check if a value exists in an array in Ruby
...rnally, you need to use a different data structure, such as a perfect hash table with fixed sized keys. Given that there's no way to test for membership in an array without looping internally, I interpreted the question to mean "without having to write the loop explicitly myself"
...