Questions tagged [sorting]

Questions on the sorting/ordering functions of Mathematica (Sort, SortBy, Ordering, etc.).

15 questions with no upvoted or accepted answers
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8
votes
0answers
110 views

What do the Internal`Compare* functions do?

As part of looking at this question I dug into Names["Internal`*Compare*"] and ended up with: ...
4
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0answers
106 views

Dataset row position changed by GroupBy in 11.0.1

Bug introduced in 11.0.0 and persisting through 11.0.1 or later In 10.4.1 and previous versions then using GroupBy in a Dataset ...
4
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0answers
94 views

How do I reassign the ordering of symbols in a polynomial expression?

I have a big polynomial expression, like this: ...
2
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0answers
45 views

SortBy without final cannonical ordering

How can I SortBy a list without final cannonical ordering? E.g. SortBy[{9, 1, 2, 5, 3, 7}, # Boole[# >= 6] & ] returns <...
2
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0answers
95 views

dynamic binary search

Suppose I have a time series of values $v_1, \dotsc, v_n, \dots,$ (think of the data as being generated by repeated function calls, like a Python generator, or being captured in real time) and I want ...
1
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0answers
91 views

how to sort an expression with descending coefficients?

I have an expression for example psi = 0.24 FF1[0] FF2[1] FF3[-1] + 0.23 FF1[0] FF2[0] FF3[1] + 0.5 FF1[1] FF2[0] FF3[1] + 0.25 FF1[1] FF2[1] FF3[1] I wonder how ...
1
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0answers
53 views

In what order does Combinatorica's SetPartitions function list the partitions of a set?

For example, Needs["Combinatorica`"] n = 4; partitions = SetPartitions[Range[n]]; Table[Print[partitions[[i]]], {i, 1, BellB[n]}] generates ...
1
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0answers
82 views

Finding correct combination of functions

I am trying to write code where I have an array $S$ or numbers in any order [5,4,2,1,....] Then I have a specific set of functions that I can write. ...
1
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0answers
274 views

Collision detection algorithm (discrete) with sweep and prune algorithm for periodic boundary conditions

EDIT: Question Updated with solution approach, but solution much slower than original implementation. Any ideas to speed up implementation? In the discussion on collision detection (see here) I asked ...
1
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0answers
83 views

How do I reassign canonical ordering of special expressions?

1. Default behavior of Sort Note: this peculiarity is described in a comment to a related question at StackOverflow but I think it's worth restating here at mma.sx. It is estabilished in ...
0
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0answers
52 views

Using SortBy on a list of a list of a list

I have quite a typical physics problem at hand, I want the eigenvalues and -vectors of a Hamiltonian matrix. I have a parameter s, which I vary in 1000 steps and for each step I want my H matrix to be ...
0
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0answers
51 views

SortBy not working in a delayed output

I have a table of large number of elements, each with three elements, say A = {{a, b, c}, {e, f, g}...}. I am using the function ...
0
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0answers
48 views

How can I get a specific ordering in the matrix and the results of a system linear equations?

I have a linear system of 22 equations and variables. When I create the matrix form it sorts the coefficients on the first row (X1, X10, X11, ...) This ordering repeats for all columns and all the ...
0
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0answers
76 views

Sort the terms of expression by the given order?

Let's assume I have the following expression : D[K[x,y],{x,1}] + D[J[x,y],{x,2},{y,2}] + D[U[x,y],{x,2},{y,1}]. Can we sort it by the order corresponding to ...
0
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0answers
41 views

Evaluating multiple processes and sort the results

I would like to evaluate the code below and sort the two parameters {f2, M}. Say that i runs from 1 to 10 ...