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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
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What is the difference between shallow copy, deepcopy and normal assignment operation?
...ble towards the existing object. The docs explain the difference between shallow and deep copies:
The difference between shallow and deep copying is only relevant for
compound objects (objects that contain other objects, like lists or
class instances):
A shallow copy constructs a new...
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.
...
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...
Same-named attributes in attrs.xml for custom view
...tyleable> com_app_view_widget, unable to find attribute customAttr For all the view I try to declare for. Any ideas?
– Dapp
Jun 9 '14 at 14:54
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When should I use malloc in C and when don't I?
I understand how malloc() works. My question is, I'll see things like this:
6 Answers
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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 is the difference between i++ and ++i?
... Neither statement is correct. Consider your first statement. i++ actually means "save the value, increment it, store it in i, then tell me the original saved value". That is, the telling happens after the incrementing, not before as you have stated it. Consider the second statement. i++ actual...