# Questions tagged [sorting]

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

13 questions with no upvoted or accepted answers
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### What do the InternalCompare* functions do?

As part of looking at this question I dug into Names["Internal*Compare*"] and ended up with: ...
0answers
105 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 ...
0answers
84 views

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

I have a big polynomial expression, like this: ...
0answers
85 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 ...
0answers
57 views

### how to sort an expression with descending coefficients?

I have an expression for example psi = 0.24 FF1 FF2 FF3[-1] + 0.23 FF1 FF2 FF3 + 0.5 FF1 FF2 FF3 + 0.25 FF1 FF2 FF3 I wonder how ...
0answers
47 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 ...
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80 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. ...
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262 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 ...
0answers
73 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 ...
0answers
44 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 ...
0answers
41 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 ...
0answers
59 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 ...
0answers
40 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 ...