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

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2
votes
1answer
77 views

Double Sorting a Matrix

Say I have two matrices {{0, 1, 2, 2}, {2, 1, 0, 2}} and {{2, 1, 0, 2}, {2, 1, 2, 0}} I then sort by the first row ...
2
votes
1answer
147 views

How to sort eigenvalues?

I am trying to find Eigenvalues to a 12x12 Matrix ($H$) dependent on two variables $x$ and $y$. Later I want to do a 3D plot of one eigenvalue ($E$) over $x$ and $y$. An analytical solution is not ...
1
vote
0answers
25 views

How to customize the order of leaf labels in a dendrogram plot?

Take the following simple case as an example: Needs["HierarchicalClustering`"] SeedRandom[99]; Sort@RandomInteger[99, {10}] gives {2, 7, 22, 34, 42, 58, 60, ...
1
vote
3answers
336 views

Matching the order of a master list of lists from a random list of lists

Using Mathematica 9, I have 2 lists of lists one master with dimensions {300, 6}. The second is some random order but has the same first ...
0
votes
1answer
43 views

Applying multiple functions to a single column in a table

I've seen similar questions, but I'm having trouble applying solutions found there to my situation. My sorting function: ...
1
vote
1answer
54 views

Sorting the words of a phrase by defined variables/associations

Is it possible to change the word order of a phrase by creating a list of possible values/variables and using the Sort function? I want a specific word order always. $(a>b>c>d)$ But the ...
3
votes
1answer
83 views

Plotting eigenvalues smoothly

I am trying to plot how the eigenvalues of a matrix change by changing a given a parameter t. Of course the ordering of the eigenvalues does not matter mathematically but it does when I want to make ...
6
votes
3answers
292 views

How to make a better `Sort` in my case

I have some file names like this: ...
2
votes
0answers
31 views

How to sort data as in Excel? [duplicate]

How to create a program in Mathematica to sort data (table with several variables) by different variable, by clicking the name of the variable, much like in Excel with freeze pane?
15
votes
4answers
520 views

Reproducing a ranking function that behaves like Excel's RANK

I tried to find a function or expression in Mathematica that produces the same output as the RANK function in Excel (see its description here), but unfortunately I ...
3
votes
2answers
84 views

Problem with Custom Sort/Split/Gather

Please help me Sort/Split/Gather/Group(by) a set of symbolic expressions! (extreme TL;DR at bottom) I have a set of symbols (which represent 2-vectors in a plane, ultimately) and I want to sort/...
1
vote
2answers
219 views

Use of Sort with custom functions

As mentionned in the topic title, I try to apply my own sorting functions to a set of elements via the Sort command. I make here a quick presentation of the subject before. 1) Method We will ...
3
votes
2answers
89 views

Role of Accuracy in numerical evaluations, SplitBy vs GatherBy

This is a follow-up question to this question. I generated a list by substituting the results of a solve[] routine and set: ...
9
votes
3answers
323 views

GatherBy/SplitBy and Sort a list

So let's say I want to group a list of points based on their distance from the origin. I would do something like: ...
2
votes
1answer
60 views

Order of importing data from files

I have many text files numbered from 1 to 1 million in numerical order. Within each text file is 5 columns of data (TAB spaced) with many rows. I effectively want to take the minimum value from each ...
0
votes
1answer
64 views

Can't sort my list numerically for larger numbers than 10 e.g. 1,10,100,2 [duplicate]

I want my files names in real numerical order so 1,2,3,10,12. However it is currently putting them in order like so: 1,10,12,2,3 Input: ...
4
votes
2answers
73 views
2
votes
1answer
243 views

What is wrong with my user-defined ordering function?

I've defined ordering function: myOrderingFunction[arg1_, arg2_] which always return True or ...
2
votes
1answer
71 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 ...
4
votes
2answers
179 views

Sort by returning positions [duplicate]

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
101 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 words,...
1
vote
0answers
62 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. ...
0
votes
1answer
61 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
54 views

Select Only Positive Values and Prepend a Title

I have the following list: ...
5
votes
1answer
105 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
78 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
451 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 ...
7
votes
2answers
310 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
49 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 ...
4
votes
2answers
118 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 ...
3
votes
2answers
228 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. ...
2
votes
1answer
61 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
41 views

Reverse order in evaluated list

I solve the following set of ODE and plot solution of S1 vs k2 (Figure 1). ...
17
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: ...
7
votes
1answer
120 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 ...
4
votes
1answer
58 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 <...
2
votes
1answer
125 views

Arrangement Order and Multiple Columns Sorting Order of Associations with Missing Keys

I have the following well-formed JSON string ...
10
votes
1answer
335 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
98 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 ...
1
vote
1answer
80 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
32 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 ...
0
votes
1answer
34 views

Sorting orthogonal null space vectors

My program generates orthogonal null space vectors such as this: ...
9
votes
4answers
479 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
212 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
109 views

Find list item before first negative value [closed]

If I have a list like this: ...
1
vote
3answers
232 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} ...
3
votes
1answer
61 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 ...
5
votes
2answers
370 views

Is there an inequality operator (Less, Greater) for lists of elements (as opposed to elements)?

Like multi-column sorting. For example, {1,3,5} > {1,2,5} would return True, while ...
1
vote
0answers
191 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 ...