ordered-set | mutable set that remembers the order of its entries
kandi X-RAY | ordered-set Summary
kandi X-RAY | ordered-set Summary
An OrderedSet is a mutable data structure that is a hybrid of a list and a set. It remembers the order of its entries, and every entry has an index number that can be looked up.
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Trending Discussions on ordered-set
QUESTION
I'm confused by the behavior of Python's set()
in this example:
ANSWER
Answered 2022-Jan-03 at 01:40To actually answer your question. Many implementations of sets use an implementation similar to hashtables. Items are hashed and placed into an "array" based on that hash value.
Notice that for small integers, hash(x) == x. So 1 will go into slot 1, 2 will go into slot 2, 3 into slot 3, etc. Then when the elements are read, you'll literally get the elements sorted.
However if your integers are bigger than the array size, then their placement in the array will be modulo the size of the array. They will no longer be sorted.
Again, I have not actually looked at the Python implementation. This is simply a possible explanation of what could be happening.
QUESTION
In a C++ std::set
(often implemented using red-black binary search trees), the elements are automatically sorted, and key lookups and deletions in arbitrary positions take time O(log n) [amortised, i.e. ignoring reallocations when the size gets too big for the current capacity].
In a sorted C++ std::vector
, lookups are also fast (actually probably a bit faster than std::set
), but insertions are slow (since maintaining sortedness takes time O(n)).
However, sorted C++ std::vector
s have another property: they can find the number of elements in a range quickly (in time O(log n)).
i.e., a sorted C++ std::vector
can quickly answer: how many elements lie between given x,y?
std::set
can quickly find iterators to the start and end of the range, but gives no clue how many elements are within.
So, is there a data structure that allows all the speed of a C++ std::set
(fast lookups and deletions), but also allows fast computation of the number of elements in a given range?
(By fast, I mean time O(log n), or maybe a polynomial in log n, or maybe even sqrt(n). Just as long as it's faster than O(n), since O(n) is almost the same as the trivial O(n log n) to search through everything).
(If not possible, even an estimate of the number to within a fixed factor would be useful. For integers a trivial upper bound is y-x+1, but how to get a lower bound? For arbitrary objects with an ordering there's no such estimate).
EDIT: I have just seen the related question, which essentially asks whether one can compute the number of preceding elements. (Sorry, my fault for not seeing it before). This is clearly trivially equivalent to this question (to get the number in a range, just compute the start/end elements and subtract, etc.)
However, that question also allows the data to be computed once and then be fixed, unlike here, so that question (and the sorted vector answer) isn't actually a duplicate of this one.
...ANSWER
Answered 2021-Oct-28 at 09:29All data structures have their pros and cons, the reason why the standard library offers a bunch of containers.
And the rule is that there is often a balance between quickness of modifications and quickness of data extraction. Here you would like to easily access the number of elements in a range. A possibility in a tree based structure would be to cache in each node the number of elements of its subtree. That would add an average log(N) operations (the height of the tree) on each insertion or deletion, but would highly speedup the computation of the number of elements in a range. Unfortunately, few classes from the C++ standard library are tailored for derivation (and AFAIK std::set
is not) so you will have to implement your tree from scratch.
QUESTION
I've been trying to install PyTorch 1.9 with Cuda (ideally 11) on my HPC but I cannot.
The cluster says:
...ANSWER
Answered 2021-Sep-23 at 06:45First of all, as @Francois suggested, try to uninstall the CPU only version of pytorch. Also in your installation script, you should use either conda
or pip3
.
Then you may want to try the following attempts:
- using
conda
: addconda-forge
channel to your command (conda install pytorch torchvision torchaudio cudatoolkit=11.1 -c pytorch -c nvidia -c conda-forge
). And make sureconda
is updated. - using
pip
: insert--no-cache-dir
into your command (pip3 --no-cache-dir install torch==1.9.0+cu111 torchvision==0.10.0+cu111 torchaudio==0.9.0 -f https://download.pytorch.org/whl/torch_stable.html
) to avoid theMemoryError
.
QUESTION
pip3 list
Package Version
------------------- ------------
apipkg 1.5
apparmor 3.0.3
appdirs 1.4.4
asn1crypto 1.4.0
brotlipy 0.7.0
certifi 2021.5.30
cffi 1.14.6
chardet 4.0.0
cmdln 2.0.0
configobj 5.0.6
createrepo-c 0.17.3
cryptography 3.3.2
cssselect 1.1.0
cupshelpers 1.0
cycler 0.10.0
decorator 5.0.9
idna 3.2
iniconfig 0.0.0
isc 2.0
joblib 1.0.1
kiwisolver 1.3.1
LibAppArmor 3.0.3
lxml 4.6.3
matplotlib 3.4.3
mysqlclient 2.0.3
nftables 0.1
notify2 0.3.1
numpy 1.21.1
opi 2.1.1
ordered-set 3.1.1
packaging 20.9
pandas 1.3.1
Pillow 8.3.1
pip 20.2.4
ply 3.11
psutil 5.8.0
py 1.10.0
pyasn1 0.4.8
pycairo 1.20.1
pycparser 2.20
pycups 2.0.1
pycurl 7.43.0.6
PyGObject 3.40.1
pyOpenSSL 20.0.1
pyparsing 2.4.7
pysmbc 1.0.23
PySocks 1.7.1
python-dateutil 2.8.2
python-linux-procfs 0.6
pytz 2021.1
pyudev 0.22.0
requests 2.25.1
rpm 4.16.1.3
scikit-learn 0.24.2
scipy 1.7.1
setuptools 57.4.0
six 1.16.0
sklearn 0.0
slip 0.6.5
slip.dbus 0.6.5
termcolor 1.1.0
threadpoolctl 2.2.0
torch 1.9.0+cu111
torchaudio 0.9.0
torchvision 0.10.0+cu111
tqdm 4.62.1
typing-extensions 3.10.0.0
urllib3 1.26.6
...ANSWER
Answered 2021-Aug-20 at 18:37It is very likely that pip3
is pointing to a different python instance.
Imagine you had python
, python3
, python3.6
and python3.8
all installed on your system. Which one would pip3
install packages for? (who knows?)
It is almost always safer to do python3.8 -m pip list/install
since you can be sure that python3.8 somefile.py
will be using the same files you just saw. (even better, do python3.8 -m venv /path/to/some/virtualenv
and then make sure that is activated, then you can be sure pip
points to the same python
)
QUESTION
If I have two unordered_set
variables with same contents (if sorted), but created differently (say, first variable only had items inserted, second one had items inserted, erased, etc. in different order, but both variables ended up with same contents), will iterating over these two variables produce values in the same order?
PS. this question is different from similar questions on iterating same unordered set twice.
...ANSWER
Answered 2021-Aug-19 at 18:09The standard does not make such guarantee. The ordering is bound to be implementation-specific.
Consider this example to see why the ordering may be different even though the content is identical: let's start with two unordered sets A
and B
that have been created and filled with values in the same order until a point when an addition of one more object would trigger rehashing.
Now consider what happens when add an object to B
, and then remove it, while not adding any objects to A
. Obviously, the two sets would be identical, but since B
went through rehashing, the order of the objects in these sets would change.
Section 23.2.5.12 of the C++11 standard discusses the equality of unordered containers. It states that the worst-case time complexity of figuring out the equality is O(n^2). This implies that there is no guarantee of the same ordering, because otherwise we would be able to check equality in O(n).
QUESTION
I'm looking for a way to insert a vector of elements into an unordered set that I have already declared. Say I have code as follows:
...ANSWER
Answered 2021-Jul-15 at 04:08Use an iterator with insert().
QUESTION
**env:**ubuntu16.04 anaconda3 python3.7.8 cuda10.0 gcc5.5
command:
...ANSWER
Answered 2020-Nov-04 at 03:33I have solved this problem! Firstly,find the file:
QUESTION
I am trying to build a docker image for a python script that I would like to deploy. This is the first time I am using docker so I'm probably doing something wrong but I have no clue what.
My System:
...ANSWER
Answered 2020-Oct-22 at 13:20EDIT: this answer just tells you how to verify what's happening in your docker image. Unfortunately I'm unable to figure out why it is happening.
How to check it?
At each step of the docker build, you can see the various layers being generated. You can use that ID to create a temporary image to check what's happening. e.g.
QUESTION
As pointed out in Using a std::unordered_set of std::unique_ptr, it is not easy to find a pointer T*
in std::unordered_set>
. Prior to C++20 we were forced to construct an instance of std::unique_ptr
.
Thanks to the Heterogeneous lookup for unordered containers proposals (http://wg21.link/P0919r3 and http://wg21.link/p1690r1), this problem is solved in C++20. But the available solution looks quite clumsy to me (even by C++ standards). It seems like I need to implement from scratch not one, but two functors (for transparent hashing and for transparent comparison):
...ANSWER
Answered 2020-Oct-13 at 10:53You can shift the verbosity into std::to_address (thanks to @Caleth for pointing that out) and the existing std::hash
, which is specialized for std::unique_ptr
to return a hash based on the raw address (thanks to @Mikhail for the hint). Then, implement hash and equality types with member function templates (note how you no longer need the types themselves be templates):
QUESTION
I am trying to define a type that's an unordered_set
over pair
s of unsigned int
:
ANSWER
Answered 2020-Sep-26 at 05:06You need to compile with C++20 mode, i.e. with the option -std=c++2a
.
Before C++20 lambda closure types have no default constructor.
Closure types are not DefaultConstructible. Closure types have no default constructor (until C++20)
If no captures are specified, the closure type has a defaulted default constructor. (since C++20)
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Install ordered-set
You can use ordered-set like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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