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Why can't I use a list as a dict key in python?
...le, it'll work correctly with classes that have a custom comparison method __eq__. But if you convert them to strings, everything is compared by its string representation.
– Aran-Fey
May 20 '18 at 12:50
...
Oracle “(+)” Operator
...e a link at the official Oracle documentation: docs.oracle.com/html/A95915_01/sqopr.htm
– Vargan
Jun 3 '15 at 16:55
...
Python list subtraction operation
...t to use the - infix syntax, you can just do:
class MyList(list):
def __init__(self, *args):
super(MyList, self).__init__(args)
def __sub__(self, other):
return self.__class__(*[item for item in self if item not in other])
you can then use it like:
x = MyList(1, 2, 3, 4...
Elegant way to invert a map in Scala
...
Assuming values are unique, this works:
(Map() ++ origMap.map(_.swap))
On Scala 2.8, however, it's easier:
origMap.map(_.swap)
Being able to do that is part of the reason why Scala 2.8 has a new collection library.
...
Google Tag Manager 入门指南 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...页脚，如：footer.inc：
<script type=”text/javascript”>
var _gaq = _gaq || [];
_gaq.push(["_setAccount", "UA-XXXXXX-1"]);
_gaq.push(["_trackPageview"]);
(function() {
var ga = document.createElement(“script”); ga.type = “text/javascript”; ga.async = true;
ga.src = (...
What is the fastest/most efficient way to find the highest set bit (msb) in an integer in C?
...
GCC has:
-- Built-in Function: int __builtin_clz (unsigned int x)
Returns the number of leading 0-bits in X, starting at the most
significant bit position. If X is 0, the result is undefined.
-- Built-in Function: int __builtin_clzl (unsigned long...
How do I spool to a CSV formatted file using SQLPLUS?
... numbers (avoid scientific notation on IDs)
spool myfile.csv
select table_name, tablespace_name
from all_tables
where owner = 'SYS'
and tablespace_name is not null;
Output will be like:
TABLE_PRIVILEGE_MAP ,SYSTEM
SYSTEM_PRIVILEGE_MAP ,S...
How to convert an image to base64 encoding?
...hould be:
$path = 'myfolder/myimage.png';
$type = pathinfo($path, PATHINFO_EXTENSION);
$data = file_get_contents($path);
$base64 = 'data:image/' . $type . ';base64,' . base64_encode($data);
share
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...
Can I serve multiple clients using just Flask app.run() as standalone?
...onal keyword arguments (**options) that it forwards to werkzeug.serving.run_simple - two of those arguments are threaded (a boolean) and processes (which you can set to a number greater than one to have werkzeug spawn more than one process to handle requests).
threaded defaults to True as of Flask ...
Flatten nested dictionaries, compressing keys
...ng the dictionary at final step.
import collections
def flatten(d, parent_key='', sep='_'):
items = []
for k, v in d.items():
new_key = parent_key + sep + k if parent_key else k
if isinstance(v, collections.MutableMapping):
items.extend(flatten(v, new_key, sep=s...