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How do I create a URL shortener?
...n auto-generated, unique numerical key (the auto-incremented id of a MySQL table for example).
For this example, I will use 12510 (125 with a base of 10).
Now you have to convert 12510 to X62 (base 62).
12510 = 2×621 + 1×620 = [2,1]
This requires the use of integer division and modulo. A pseudo...
Creating an R dataframe row-by-row
...
data.table seems to be even faster than pre-allocation using data.frames. Testing here: stackoverflow.com/a/11486400/636656
– Ari B. Friedman
Jul 15 '12 at 2:02
...
It is more efficient to use if-return-return or if-else-return?
...most all if-else-return are cases of guard clauses and those are always testable (mock the tested expression) without the else.
– cowbert
Mar 28 '18 at 3:22
...
Check if Python Package is installed
...s:
import subprocess
import sys
reqs = subprocess.check_output([sys.executable, '-m', 'pip', 'freeze'])
installed_packages = [r.decode().split('==')[0] for r in reqs.split()]
The result:
print(installed_packages)
[
"Django",
"six",
"requests",
]
Check if requests is installed:
i...
Which Java Collection should I use?
...resenting a Collection with no duplicates.
HashSet: A Set backed by a Hashtable. Fastest and smallest memory usage, when ordering is unimportant.
LinkedHashSet: A HashSet with the addition of a linked list to associate elements in insertion order. The "next" element is the next-most-recently insert...
How to atomically delete keys matching a pattern using Redis
...
Lua's unpack transforms a table in a "list of independent variables" (other languages call that explode) but the max number is not dependent on the syste memory; it's fixed in lua through the LUAI_MAXSTACK constant. In Lua 5.1 & LuaJIT it's 8000 a...
What is the purpose of base 64 encoding and why it used in HTTP Basic Authentication?
...- it's an encoding. It's a way of representing binary data using only printable (text) characters.
See this paragraph from the wikipedia page for HTTP Basic Authentication:
While encoding the user name and password with the Base64 algorithm typically makes them unreadable by the naked eye, the...
Get average color of image via Javascript
...been working on refactoring my execution to:
- store results in a lookup table for future use in the iteration over each pixel.
- to divide large images into grids of 20px 20px for localized dominance.
- to use the euclidean distance between x1y1 and x1y2 to figure out the distance between x1y...
jQuery UI DatePicker to show month year only
...
<style>
.ui-datepicker table{
display: none;
}
<script type="text/javascript">
$(function() {
$( "#manad" ).datepicker({
changeMonth: true,
changeYear: true,
showButtonPanel: true,
dateFormat: 'yy-m...
How does this print “hello world”?
...binary representations for the lowercase
alphabet letters in the following table:
ascii | ascii | ascii | algorithm
character | decimal value | binary value | 5-bit codification
--------------------------------------------------------------
space | 32 | 01000...