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Counting array elements in Python [duplicate]
... out as 2, as does len(array([[0, 0], [0, 0]])).
– EL_DON
Jan 19 '18 at 22:49
how about index of array? for example, w...
What is the __DynamicallyInvokable attribute for?
...q.Enumerable in DotPeek I notice that some methods are flavoured with a [__DynamicallyInvokable] attribute.
2 Answers
...
How to add column if not exists on PostgreSQL?
...statement:
DO $$
BEGIN
BEGIN
ALTER TABLE <table_name> ADD COLUMN <column_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
...
Override Python's 'in' operator?
...
MyClass.__contains__(self, item)
share
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Setting up two different static directories in node.js Express framework
...nal (first) parameter to use() like so:
app.use("/public", express.static(__dirname + "/public"));
app.use("/public2", express.static(__dirname + "/public2"));
That way you get two different directories on the web that mirror your local directories, not one url path that fails over between two lo...
How to change the name of a Django app?
...ls.py , 'manage.py' , and settings.py files.
Edit the database table django_content_type with the following command: UPDATE django_content_type SET app_label='<NewAppName>' WHERE app_label='<OldAppName>'
Also if you have models, you will have to rename the model tables. For postgres use...
Python debugging tips [closed]
...
PDB
You can use the pdb module, insert pdb.set_trace() anywhere and it will function as a breakpoint.
>>> import pdb
>>> a="a string"
>>> pdb.set_trace()
--Return--
> <stdin>(1)<module>()->None
(Pdb) p a
'a string'
(Pdb)
To...
Regular expression for letters, numbers and - _
...he pattern you want is something like (see it on rubular.com):
^[a-zA-Z0-9_.-]*$
Explanation:
^ is the beginning of the line anchor
$ is the end of the line anchor
[...] is a character class definition
* is "zero-or-more" repetition
Note that the literal dash - is the last character in the ch...
How to write header row with csv.DictWriter?
...od now available in 2.7 / 3.2:
from collections import OrderedDict
ordered_fieldnames = OrderedDict([('field1',None),('field2',None)])
with open(outfile,'wb') as fou:
dw = csv.DictWriter(fou, delimiter='\t', fieldnames=ordered_fieldnames)
dw.writeheader()
# continue on to write data
...
How to iterate for loop in reverse order in swift?
... an array with one trillion Ints!
Test:
var count = 0
for i in lazy(1...1_000_000_000_000).reverse() {
if ++count > 5 {
break
}
println(i)
}
For Swift 2.0 in Xcode 7:
for i in (1...10).reverse() {
print(i)
}
Note that in Swift 2.0, (1...1_000_000_000_000).reverse(...