大约有 31,100 项符合查询结果（耗时：0.0510秒） [XML]
count the frequency that a value occurs in a dataframe column
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Using list comprehension and value_counts for multiple columns in a df
[my_series[c].value_counts() for c in list(my_series.select_dtypes(include=['O']).columns)]
https://stackoverflow.com/a/28192263/786326
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What is the standard Python docstring format? [closed]
...ollow their own numpydoc based on Google format and usable by Sphinx.
"""
My numpydoc description of a kind
of very exhautive numpydoc format docstring.
Parameters
----------
first : array_like
the 1st param name `first`
second :
the 2nd param
third : {'value', 'other'}, optional
the 3...
Filtering a list based on a list of booleans
...e, if you have an array, a, instead of list_a:
a = np.array([1, 2, 4, 6])
my_filter = np.array([True, False, True, False], dtype=bool)
a[my_filter]
> array([1, 4])
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Select distinct values from a table field
I'm struggling getting my head around the Django's ORM. What I want to do is get a list of distinct values within a field on my table .... the equivalent of one of the following:
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Pointer to class data member “::*”
...olve some tricky problems. But to be honest, I've never had to use them in my own code.
Edit: I can't think off-hand of a convincing use for pointers to member data. Pointer to member functions can be used in pluggable architectures, but once again producing an example in a small space defeats me....
Red black tree over avl tree
...ted as binary trees, the red/black-flags simulate 2-3 behaviour
As far as my own understanding goes, AVL trees and RB trees are not very far off in terms of performance. An RB tree is simply a variant of a B-tree and balancing is implemented differently than an AVL tree.
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Regular expression for a hexadecimal number?
...uby, you can do:
/\h+/
EDIT - Steven Schroeder's answer made me realise my understanding of the 0x bit was wrong, so I've updated my suggestions accordingly.
If you also want to match 0x, the equivalents are
/0[xX][0-9a-fA-F]+/
/0x[0-9a-f]+/i
/0x[\h]+/i
ADDED MORE - If 0x needs to be optional ...
How to convert lazy sequence to non-lazy in Clojure
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This is to some degree a question of taxonomy. a lazy sequence is just one type of sequence as is a list, vector or map. So the answer is of course "it depends on what type of non lazy sequence you want to get:
Take your pick from:
an ex-lazy (fully evaluated) la...
Understanding the meaning of the term and the concept - RAII (Resource Acquisition is Initialization
...programmer might not even be aware of. Here are a few examples beyond the "my local variables will be destroyed whenever I return".
Let us start with an overly simplistic FileHandle class employing RAII:
class FileHandle
{
FILE* file;
public:
explicit FileHandle(const char* name)
{
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How to load program reading stdin and taking parameters in gdb?
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If you were doing it from a shell you'd do it like this:
% gdb myprogram
gdb> run params ... < input.txt
This seems to work within emacs too.
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