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Read-only and non-computed variable properties in Swift
...property which returns that property:
public class Clock {
private var _hours = 0
public var hours: UInt {
return _hours
}
}
But this can be achieved in a different, shorter way, as stated in the section "Access Control" of the "The Swift Programming Language" book:
public class Clo...
mongodb count num of distinct values per field/key
...}
},
{ $unwind: "$keywords" },
{
$group: {
_id: {$toLower: '$keywords'},
count: { $sum: 1 }
}
},
{
$match: {
count: { $gte: 2 }
}
},
{ $sort : { count : -1} },
{ $limit : 100 }
]);
that give result ...
Converting between datetime, Timestamp and datetime64
...amp(ts)
datetime.datetime(2012, 12, 4, 19, 51, 25, 362455)
>>> np.__version__
'1.8.0.dev-7b75899'
The above example assumes that a naive datetime object is interpreted by np.datetime64 as time in UTC.
To convert datetime to np.datetime64 and back (numpy-1.6):
>>> np.datetime6...
Find out time it took for a python script to complete execution
...test function"
L = []
for i in range(100):
L.append(i)
if __name__=='__main__':
from timeit import Timer
t = Timer("test()", "from __main__ import test")
print t.timeit()
Then to convert to minutes, you can simply divide by 60. If you want the script runtime in an easi...
How do I do base64 encoding on iOS?
...ve posted it here:
First, you need the mapping tables:
static const char _base64EncodingTable[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const short _base64DecodingTable[256] = {
-2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -1, -2, -1, -1, -2, -2,
-2, -2, -...
How is a CRC32 checksum calculated?
... 1100001010 = Quotient (nobody cares about the quotient)
_______________
10011 ) 11010110110000 = Augmented message (1101011011 + 0000)
=Poly 10011,,.,,....
-----,,.,,....
10011,.,,....
10011,.,,....
-----,.,,....
00001.,,....
...
How do I include a pipe | in my linux find -exec command?
...o use your top level shell to perform the piping like so:
find -name 'file_*' -follow -type f -exec zcat {} \; | agrep -dEOE 'grep'
In terms of efficiency this results costs one invocation of find, numerous invocations of zcat, and one invocation of agrep.
This would result in only a single agre...
What's the difference between a Python module and a Python package?
...le (or files) that are imported under one import and used.
e.g.
import my_module
A package is a collection of modules in directories that give a package hierarchy.
from my_package.timing.danger.internets import function_of_love
Documentation for modules
Introduction to packages
...
Assigning a variable NaN in python without numpy
...e 1, in <module>
File "C:\Python35\lib\fractions.py", line 146, in __new__
numerator)
ValueError: Invalid literal for Fraction: 'nan'
>>>
>>> Fraction(float('nan'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Python35\...
How can I hash a password in Java?
...m recommended cost, used by default
*/
public static final int DEFAULT_COST = 16;
private static final String ALGORITHM = "PBKDF2WithHmacSHA1";
private static final int SIZE = 128;
private static final Pattern layout = Pattern.compile("\\$31\\$(\\d\\d?)\\$(.{43})");
private final Se...