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

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2
votes
1answer
237 views

What is wrong with my user-defined ordering function?

I've defined ordering function: myOrderingFunction[arg1_, arg2_] which always return True or ...
1
vote
1answer
58 views

How to check a clockwise direction for a list of point [closed]

Suppose that we have a list of points and we need to order them in clockwise direction by starting from a special point. I implemented this code to order them but I need to detect if it is ordered in ...
3
votes
1answer
146 views

Sort by returning positions

How can I computationally efficiently sort a list so as to return the positions and not the actual values at those positions (which SortBy does)?
4
votes
3answers
87 views

Change Contour Plot Overlap Ordering

I have a contour plot for which I have selected a finite set of contours. However, the contours overlap in some places and I would like to reverse the order in which they are drawn. In other ...
3
votes
0answers
295 views

Negative power instead of fraction [duplicate]

Solve returns a solution in the form {{ x -> y / a^2 + y^2 / a^7 }}. Since I want to process the input (with another program) in terms of Laurent polynomials, I ...
1
vote
0answers
57 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. ...
19
votes
4answers
406 views

Unexpected result {“.a”, “co”, “.m”} from Sort[{“.m”, “.a”, “co”}]

I came across the following situation: Evaluating Sort[{".m", ".a", "co"}] Results in {".a", "co", ".m"} I wondering: ...
0
votes
1answer
52 views

Unexpected result from Sort with symbolic values

I think Sort should be able to sort symbolic values that are reducible to numerical values, but this example seems to get a wrong answer (here is a simplified ...
2
votes
2answers
38 views
5
votes
1answer
83 views

How to order a list to match the order of another list?

How can I order a list to match the order of anoter list ? For example: Suppose I have the lists x = {3, 1, 5, 7} and ...
3
votes
1answer
68 views

SortBy behaving strangely with missing data

I'm trying to create a grid that shows the largest data value from a list. What I have mostly works- the problem comes when there is missing data. You can't really tell here, but all of the ...
11
votes
5answers
423 views

How to sort list of mixed types of elements with each type a specified canonical order?

For example, here is a list {{1, "u"}, {6, "d"}, {3, "u"}, {4, "d"}, {2, "u"}, {5, "u"}, {3, "d"}, {1, "d"}, {4, "u"}, {2, "d"}, {5, "d"}, {6, "u"}} The ...
6
votes
2answers
249 views

Wolfram Language symbols by their Ranks

I'd like to get the top 50, the bottom 50 and an ordered list of all Wolfram Language symbols based on their "Ranks". With ...
0
votes
1answer
39 views

Sorting in descending order of list [closed]

I have a list m = {{a, 20}, {b, 10}, {c, 50}, {d, 5}, {e, 100}} and I want to apply Sort on this in descending order on ...
3
votes
2answers
222 views

Exercise using Sort

I have to order the following list according to the sum of the powers of each element of the list, using the function Sort. ...
4
votes
2answers
111 views

Sorting and keeping the main format of list numbers [duplicate]

I have a list with these elements: list={1/2 (1 + Sqrt[5]), 1, 1, 1/2 (1 - Sqrt[5]), 0}; I want to sort them with ...
1
vote
2answers
122 views

How do I use Subgraph to sample the $n$ vertices of a graph with the greatest connectivity?

Let $G$ be an arbitrary graph with some number of vertices $||V||$ and some number of edges $||E||$. We can use Subgraph to generate, well, a subgraph of ...
6
votes
2answers
378 views

Position function not always returning an answer even with no apparent problems

I'm having some problems with Position. Sometimes it will give an empty list instead of the actual position of the element I am looking for when that element is ...
22
votes
3answers
3k views

Sort data after specific ordering (ascending/descending) in multiple columns

I have some data: data={{"a", 1, 1}, {"a", 1, 2}, {"a", 1, 3}, {"c", 2, 1}, {"b", 2, 2}, {"b", 2, 3}, {"c", 3, 1}, {"a", 3, 2}, {"a", 3, 3}} When I ...
1
vote
3answers
128 views

Complement[] changes order of elements?

Consider this example: Complement[{a, y, c, d, e}, {a, c}, {d}] (*{e, y}*) However, I was expecting the result to be: ...
2
votes
1answer
52 views

Sort a list of derivatives

I have a list of variables, both constant and functions of an independent variable, including derivatives. I'd like to sort these by the variable name, rather than the derivative order. For example, ...
1
vote
1answer
36 views

Reverse order in evaluated list

I solve the following set of ODE and plot solution of S1 vs k2 (Figure 1). ...
5
votes
1answer
729 views

How to implement Kemeny-Young method? (rank aggregation problem)

Prehistory I am trying to make some statistical analysis of some experimental data, arises from measurements made ​​on an ordinal scale. I faced with the problem of rank aggregation: to get from ...
3
votes
1answer
56 views

Sort Unicode characters

Sorting ASCII phrases works fine: Sort[{"albatrob", "abo", "dict", "star", "mangel", "m"}] (*{"abo", "albatrob", "dict", "m", "mangel", "star"}*) But unless I'm ...
14
votes
3answers
2k views

How to sort colors properly?

I can't seem to be able to sort colors by their hue and perceptual brightness correctly. Here's my current solution, but it's not right; there are all these dark bands: ...
2
votes
1answer
630 views

How do I sort complex numbers?

Okay, so I posted something about sorting, and it was linked as a duplicate to This post However, I am having problems trying to sort a list that contains both real and complex numbers. I put them ...
7
votes
1answer
115 views

Challenging matrix sorting request?

I have an application in mind, and I need to do the following analysis, but am having a high degree of difficulty conceptualizing it in terms of syntax. I understand what I want, but cannot seem to ...
9
votes
2answers
343 views

Complement on pre-sorted lists

Is there any way to instruct Complement to skip the sorting part? If the answer is no (likely), the next question would be: how can I remove from a sorted list ...
4
votes
1answer
57 views

How to canonically reorganize a list using only a limited set of manipulations?

I want to canonically reorganize (like Sort) a sequence of four objects seq[a,b,c,d], but the only manipulations allowed are ...
10
votes
1answer
266 views

Lexicographic ordering of lists-of-lists?

I was surprised to discover that Mathematica does not sort lists-of-lists (LLs) lexicographically by default. For example, applying Sort to ...
6
votes
1answer
95 views

SameQ for unsorted lists

I have to compare two or more lists and check if they are the same, but their elements can be in different position. For instance ...
5
votes
2answers
819 views

How to plot several functions without jumping? (multiple eigenvalues of a system as functions of 2 parameters)

I've been working on this research problem for months with some success by no global/proper solution to the problem. So I have square, Hermitian matrices of various sizes ($8,20,38$ dimensions) with ...
1
vote
1answer
77 views

Descending order of Permutations using Select[Tuples[{5, 4, 3, 2, 1}, {3}], OrderedQ]

I was wondering if there is a possible way to still use OrderedQ and get a descending order of permutations: This is Ascending order: ...
0
votes
0answers
31 views

I have trouble in sorting a matrix in wolfram mathematica [duplicate]

I have an array of five elements, I have to make permutations of 3 elements. I have my code: A = {1, 2, 3, 4, 5}; n = Permutations[A, {3}]; Now I have to sort ...
6
votes
2answers
883 views

Sort matrix by columns and rows without changing them

I would like to sort a matrix in descending order first by the total of each column, then by the total of each row, but without changing their content. For example, if I had: ...
0
votes
1answer
33 views

Sorting orthogonal null space vectors

My program generates orthogonal null space vectors such as this: ...
9
votes
4answers
410 views

Difference between Sort and SortBy

I was playing with Sort. All examples I have come across so far, i.e Sort[{1, -1, 3, -3, 2, 5}, Abs[#1]<Abs[#2]&] can expressed in a shorter fashion ...
2
votes
2answers
203 views

Are there any good mass row/column swapping functions for matrices?

I have the following matrix Keeping the 20 row and 20 column fixed (so the 21st rows and columns because I started at 0)...how do I push each row and column back one spot? I need to push the 0th row ...
2
votes
5answers
108 views
1
vote
3answers
200 views

How to sort the list of all possible 3-tuples of elements from list constrained by a condition?

I want to know if there's a way to impose desired condition on Tuple command output. I have generated a list of 3-tuple of elements from {1,2,3,4,5,6,7,8,9,10} ...
0
votes
2answers
90 views

Sorting non-numerical lists [duplicate]

The Sort function will by default sort from lowest to highest. In[1]:= Sort[{3, 1, 4}] Out[1]= {1, 3, 4} However, if the list ...
1
vote
0answers
178 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 ...
5
votes
2answers
367 views
2
votes
3answers
236 views

Finding minimum of a list of pairs

Sometimes I need to find the Min of a list, whose elements are lists (say of two elements, a pair). Given that Min does not have the option to indicate a sorting function like Sort, I elaborated the ...
1
vote
1answer
58 views

Error with using SortBy in a Map [closed]

I have a data set in the following format: SomeData = {{a, 1, 2}, {b, 2, 3}, {c, 3, 4}, {b, 1, 9}, {c, 1, 10}, {a, 2, 3}, {a, 3, 8}, {b, 3, 4}, {c, 2, 9}}; The ...
1
vote
0answers
43 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
votes
0answers
25 views

Sort giving unexpted output! [duplicate]

I want to perform sorting on a list of strings, If i take for example the list s s={"test9","test8","test10"}; If i perform the Sort function i will get: ...
1
vote
1answer
105 views

Importing, sorting and exporting lists

I have several TSV lists (.txt) of something like 2000*2000 numerics (e.g. 1.8645) to import ...
2
votes
4answers
95 views

While subpartitioning the elements in list using GatherBy, can I corresponding subpartition the elements of an unrelated list?

If we have a list like the following: list1 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}; And we use GatherBy to subpartition is according to a test function ...