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What is a regular expression which will match a valid domain name without a subdomain?
...ote, to use this regex, you will need to convert the domain to lower case, and also use an IDN library to ensure you encode domain names to ACE (also known as "ASCII Compatible Encoding"). One good library is GNU-Libidn.
idn(1) is the command line interface to the internationalized domain name libr...
How to check if a line is blank using regex
...e character class.
* is zero-or-more repetition of.
In multiline mode, ^ and $ also match the beginning and end of the line.
References:
regular-expressions.info/Anchors, Character Classes, and Repetition.
A non-regex alternative:
You can also check if a given string line is "blank" (i.e. ...
About Android image and asset sizes
...imply using hdpi assets.
What this means is if you're doing a 48dip image and plan to support up to xxhdpi resolution, you should start with a 144px image (192px if you want native assets for xxxhdpi) and make the following images for the densities:
ldpi | mdpi | tvdpi | hdpi | xhdpi ...
Pandas groupby: How to get a union of strings
...065 This
1 2 0.301084 is
2 3 0.463468 a
3 4 0.643961 random
4 1 0.866521 string
5 2 0.120737 !
In [6]: df.dtypes
Out[6]:
A int64
B float64
C object
dtype: object
When you apply your own function, there is not automatic exclusions of non-numeric columns...
Add one row to pandas DataFrame
I understand that pandas is designed to load fully populated DataFrame but I need to create an empty DataFrame then add rows, one by one .
What is the best way to do this ?
...
What does -fPIC mean when building a shared library?
I know the ' -fPIC ' option has something to do with resolving addresses and independence between individual modules, but I'm not sure what it really means. Can you explain?
...
How to use JavaScript source maps (.map files)?
...js.map extension shipped with some JavaScript libraries (like Angular ), and that just raised few questions in my head:
5...
Ruby on Rails Callback, what is difference between :before_save and :before_create?
Could you explain in detail what the :before_save and :before_create Ruby on Rails callbacks are, and what they have to do with Rails validations? Does validation occur after :before_save or :before_create ?
...
What are Long-Polling, Websockets, Server-Sent Events (SSE) and Comet?
...
In the examples below the client is the browser and the server is the webserver hosting the website.
Before you can understand these technologies, you have to understand classic HTTP web traffic first.
Regular HTTP:
A client requests a webpage from a server.
The server...
Difference between os.getenv and os.environ.get
...s about os.environ.get() which returns None (unless specified differently) and never raises an exception if the env. var. doesn't exists. Your confusing things with using os.environ['TERM'] which is not what the question is about.
– Anthon
Apr 21 '17 at 7:41
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