combinations | Go lang combination package
kandi X-RAY | combinations Summary
kandi X-RAY | combinations Summary
A package with combinations functions from python itertools. For now the following iterators are implemented :.
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Currently covering the most popular Java, JavaScript and Python libraries. See a Sample of combinations
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Trending Discussions on combinations
QUESTION
I am trying to generate all directed graphs with a given number of nodes up to graph isomorphism so that I can feed them into another Python program. Here is a naive reference implementation using NetworkX, I would like to speed it up:
...ANSWER
Answered 2022-Mar-31 at 13:5898-99% of computation time is used for the isomorphism tests, so the name of the game is to reduce the number of necessary tests. Here, I create the graphs in batches such that graphs have to be tested for isomorphisms only within a batch.
In the first variant (version 2 below), all graphs within a batch have the same number of edges. This leads to appreaciable but moderate improvements in running time (2.5 times faster for graphs of size 4, with larger gains in speed for larger graphs).
In the second variant (version 3 below), all graphs within a batch have the same out-degree sequence. This leads to substantial improvements in running time (35 times faster for graphs of size 4, with larger gains in speed for larger graphs).
In the third variant (version 4 below), all graphs within a batch have the same out-degree sequence. Additionally, within a batch all graphs are sorted by in-degree sequence. This leads to modest improvements in speed compared to version 3 (1.3 times faster for graphs of size 4; 2.1 times faster for graphs of size 5).
QUESTION
I would like to generate a list of combinations. I will try to simplify my problem to make it understandable.
We have 3 variables :
- x : number of letters
- k : number of groups
- n : number of letters per group
I would like to generate using python a list of every possible combinations, without any duplicate knowing that : i don't care about the order of the groups and the order of the letters within a group.
As an example, with x = 4, k = 2, n = 2 :
...ANSWER
Answered 2022-Mar-31 at 18:01Firstly, you can use a list comprehension to give you all of the possible combinations (regardless of the duplicates):
QUESTION
With the parent-child
relationships data frame as below:
ANSWER
Answered 2022-Feb-25 at 08:17We can use ego
like below
QUESTION
I want to generate vectors with all possible combinations of vector elements where a consecutive multiple occurrences of an element is considered as single occurrence of that element.
Simple cases
For n = 2,
...ANSWER
Answered 2022-Feb-17 at 17:32Using chartr
, you can do (although this might crash for larger vectors):
QUESTION
The following is an example of items rated by 1,2 or 3 stars. I am trying to count all combinations of item ratings (stars) per month.
In the following example, item 10 was rated in month 1 and has two ratings equal 1, one rating equal 2 and one rating equal 3.
...ANSWER
Answered 2022-Feb-20 at 22:37Series.value_counts
+ Series.unstack
to convert to dataframe
QUESTION
Apparently, discord bots can have mobile status as opposed to the desktop (online) status that one gets by default.
After a bit of digging I found out that such a status is achieved by modifying the IDENTIFY packet
in discord.gateway.DiscordWebSocket.identify
modifying the value of $browser
to Discord Android
or Discord iOS
should theoretically get us the mobile status.
After modifying code snippets I found online which does this, I end up with this :
...ANSWER
Answered 2022-Feb-07 at 23:03The following works by subclassing the relevant class, and duplicating code with the relevant changes. We also have to subclass the Client
class, to overwrite the place where the gateway/websocket class is used. This results in a lot of duplicated code, however it does work, and requires neither dirty monkey-patching nor editing the library source code.
However, it does come with many of the same problems as editing the library source code - mainly that as the library is updated, this code will become out of date (if you're using the archived and obsolete version of the library, you have bigger problems instead).
QUESTION
I am trying to define a function that takes a data frame or table as input with a specific number of ID columns (e.g., 2 or 3 ID columns), and the remaining columns are NAME1, NAME2, ..., NAMEK (numeric columns). The output should be a data table that consists of the same ID columns as before plus one additional ID column that groups each unique pairwise combination of the column names (NAME1, NAME2, ...). In addition, we must gather the actual values of the numeric columns into two new columns based on the ID column; an example with two ID columns and three numeric columns:
...ANSWER
Answered 2021-Dec-29 at 11:06Attention:
Here is an inspiring idea which is not fully satisfy OP's requirement (e.g., ID.new and number order) but I think it worth to be recoreded here.
You can turn DT
into long format by melt
firstly.
Then to shift
value with the step -nrow(DT)
in order to do
the minus operation, i.e. NAME1 - NAME2, NAME2 - NAME3, NAME3 - NAME1
.
QUESTION
I have a df
:
ANSWER
Answered 2021-Nov-16 at 08:55This is what you need:
QUESTION
I want to deconstruct a pandas DataFrame, using column headers as a new data-column and create a list with all combinations of the row index and columns. Easier to show than explain:
...ANSWER
Answered 2021-Nov-09 at 23:58The structure that you want your data in is very messy, so this is probably the best method given the data you want.
QUESTION
Given numbers 1 to 3n, construct n equations of the form a + b = c
or a x b = c
such that each number is used exactly once. For example:
ANSWER
Answered 2021-Oct-09 at 23:01This looks like a combinatorial problem where its "messiness" suggests no mathematical answer can be formulated. The cheer number of allowed combinations makes it ever more likely that each n
has a valid solution, especially given that for small n
you already found solutions.
Finding solutions for larger n
can be tricky. One approach is called "simulated annealing", where you would take a random set of equations, I try to improve it step by step. "Bad equations" (i.e. equations that have numbers overlapping with others in the set) get removed, and new equations are tried.
Whatever approach is used, it probably can be speed up with heuristics. Such as start creating equations for numbers that show up in the least number of possible equations.
A somewhat related problem is called "graceful labeling", which has no definite answer and for which similar algorithms are appropriate.
Here is an approach using z3py, a library which implements a sat/smt solver.
First, for each number, a list of possible expressions is made. For each possible expression, a symbolic boolean indicates whether the expression will be used in the solution. To have a valid solution, for each number, exactly one of its possible expressions should be True.
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