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How to check whether a pandas DataFrame is empty?
...[8]: len(df1.columns)
Out[8]: 0
In [9]: len(df2.columns)
Out[9]: 2
Critically, while the second dataframe df2 contains no data, it is not completely empty because it returns the amount of empty columns that persist.
Why it matters
Let's add a new column to these dataframes to understand the implic...
How to create a unique index on a NULL column?
...rver 2005. I want to constrain the values in a column to be unique, while allowing NULLS.
4 Answers
...
E731 do not assign a lambda expression, use a def
...rst form means that the name of the resulting
function object is specifically 'f' instead of the generic '<lambda>'.
This is more useful for tracebacks and string representations in
general. The use of the assignment statement eliminates the sole
benefit a lambda expression can offer o...
How do CUDA blocks/warps/threads map onto CUDA cores?
I have been using CUDA for a few weeks, but I have some doubts about the allocation of blocks/warps/thread.
I am studying the architecture from a didactic point of view (university project), so reaching peak performance is not my concern.
...
How to securely store access token and secret in Android?
...other apps cannot access them. On a rooted devices, if the user explicitly allows access to some app that is trying to read them, the app might be able to use them, but you cannot protect against that. As for encryption, you have to either require the user to enter the decrypt passphrase every time ...
HEAD and ORIG_HEAD in Git
..., and it is a commit on top of which "git commit" would make a new one. Usually HEAD is symbolic reference to some other named branch; this branch is currently checked out branch, or current branch. HEAD can also point directly to a commit; this state is called "detached HEAD", and can be understood...
What's the difference between window.location= and window.location.replace()?
...er won't be able to use the Back
button to navigate to it.
Oh and generally speaking:
window.location.href = url;
is favoured over:
window.location = url;
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What are the relative strengths and weaknesses of Git, Mercurial, and Bazaar? [closed]
...ike that very much.
Bazaar is reasonably fast (very fast for trees with shallow history, but presently scales poorly with history length), and is easy-to-learn to those familiar with the command-line interfaces of traditional SCMs (CVS, SVN, etc). Win32 is considered a first-class target by its dev...
Create a custom View by inflating a layout?
...reate a Compound Control. You'll create a subclass of RelativeLayout, add all our your components in code (TextView, etc), and in your constructor you can read the attributes passed in from the XML. You can then pass that attribute to your title TextView.
http://developer.android.com/guide/topics...
Entity Framework and Connection Pooling
...tion Pooling (ADO.NET))
Never ever use global context. ObjectContext internally implements several patterns including Identity Map and Unit of Work. Impact of using global context is different per application type.
For web applications use single context per request. For web services use single con...