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What are the differences between numpy arrays and matrices? Which one should I use?
...
Or just np.linalg.matrix_power(mat, n)
– Eric
Feb 28 '17 at 11:16
I...
How can I check for Python version in a program that uses new language features?
...oesn't have ternary
Also, with is available in Python 2.5, just add from __future__ import with_statement.
EDIT: to get control early enough, you could split it into different .py files and check compatibility in the main file before importing (e.g. in __init__.py in a package):
# __init__.py
#...
“Incorrect string value” when trying to insert UTF-8 into MySQL via JDBC?
...y 4 bytes in UTF-8.
You may also have to set the server property character_set_server to utf8mb4 in the MySQL configuration file. It seems that Connector/J defaults to 3-byte Unicode otherwise:
For example, to use 4-byte UTF-8 character sets with Connector/J, configure the MySQL server with cha...
Test if a variable is a list or tuple
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How about: hasattr(a, "__iter__") ?
It tells if the object returned can be iterated over as a generator. By default, tuples and lists can, but not the string types.
share...
Convert hyphens to camel case (camelCase)
...and have it included in your project.
var str = 'my-hyphen-string';
str = _.camelCase(str);
// results in 'myHyphenString'
share
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Update multiple rows in same query using PostgreSQL
... one column, it's much more generalizable:
update test as t set
column_a = c.column_a
from (values
('123', 1),
('345', 2)
) as c(column_b, column_a)
where c.column_b = t.column_b;
You can add as many columns as you like:
update test as t set
column_a = c.column_a,
column_c...
_DEBUG vs NDEBUG
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Visual Studio defines _DEBUG when you specify the /MTd or /MDd option, NDEBUG disables standard-C assertions. Use them when appropriate, ie _DEBUG if you want your debugging code to be consistent with the MS CRT debugging techniques and NDEBUG if ...
The most accurate way to check JS object's type?
... constructor:
Native Type Ex1:
var string1 = "Test";
console.log(string1.__proto__.constructor.name);
displays:
String
Ex2:
var array1 = [];
console.log(array1.__proto__.constructor.name);
displays:
Array
Custom Classes:
function CustomClass(){
console.log("Custom Class Object C...
Adding Core Data to existing iPhone project
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All the CoreData header files are imported in App_Prefix.pch, so the CoreData classes will be available throughout your Project, so you don't have to manually import the header in the files you need them.
So open up Xcode and look for some file like App_Prefix.pch, by defa...
How to implement a rule engine?
...;
// use a method call, e.g. 'Contains' -> 'u.Tags.Contains(some_tag)'
return Expression.Call(left, method, right);
}
}
Note that I used 'GreaterThan' instead of 'greater_than' etc. - this is because 'GreaterThan' is the .NET name for the operator, therefore we don't need any...