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

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19
votes
5answers
1k views

How do I reassign canonical ordering of symbols?

I have a big polynomial that evaluates to: $$A^2 e^2 \phi ^- \phi ^++A e \phi ^- \phi ^+ c_{2 w} g_Z+\frac{1}{2} A e g h W^- \phi ^+ +\ll13\gg,$$ which is supposed to represent some terms in the ...
0
votes
1answer
193 views

Sorting lists of lists with string elements [closed]

I have a list of sublists. One element of each sublist is a string element. For example: list = {{1, "banana", 3}, {3, "orange", 1}, {2, "apple", 2}}; When I ...
5
votes
2answers
256 views

Sorting a large file

I have some huge logs, which are text files, containing up to a million rows each, and I need them sorted. Because trying to import one obviously makes Mathematica run out of memory, we must rule out ...
2
votes
3answers
329 views

Re-arranging / selecting of a data table very slow in For loop [duplicate]

My task is quite simple; I have a table of data like M = {{1,2}, {1,3}, {3,4}, {5,1}, {6,9}, {6,8}, {6,1}}; so the table is sorted with respect to the first ...
10
votes
2answers
461 views

Rearranging a List

I am trying to rearrange/sort a list i.e. {{1,2},{10,140},{43,10},{1,140},{43,2}} into ...
0
votes
1answer
74 views

Produce a 1-dimensional list of all unique matrix elements

We have some symbolic matrix m, e.g. m={{1, x, 4 x + y},{0, x y + 4x, 4x},{7 x, x, 4x + x y}} and we want to produce as output a list of all the unique elements ...
2
votes
1answer
363 views

Rank functions of n by their order of growth

I'd like to rank some functions according to their order of growth (e.g. n^2 < n^3). I'm not sure how to do order of growth in mathematica, so I was trying to ...
5
votes
1answer
186 views

Are there functions or packages in Mathematica to sort subsets in lex order, colex, revlex, etc.?

I am looking for non-canonical sorts of lists. A function that would give: Sort[X, "order type"] With "order type" being colex, revlex, etc.
1
vote
2answers
230 views

Sorting lists element by element [duplicate]

I have a problem regarding list sorting. Let's say I have a list of lists obtained using Subsets[], of the form ...
3
votes
1answer
242 views

Windows Explorer Natural Order

Currently there are a list of notebooks in Windows that I am processing in a folder. Ideally I would like the notebooks to be concated in the same order as how they display in Windows Explorer. I ...
1
vote
2answers
202 views

How to sort Table/Matrix including legend(Labellings)

I want to sort table including its legend for graph I have table similar to M1 M2 M3 1 5 2 3 1 4 4 2 -10 5 7 11 6 -2 1 ...
0
votes
1answer
108 views

Problem with Sort - unexpected order with Sqrt [duplicate]

Sort[{13, Sqrt[157], Sqrt[163]}] (*{13, Sqrt[157], Sqrt[157]}*) Sort[{13, Sqrt[157], Sqrt[157]}, #1 < #2 &] (*{Sqrt[157], Sqrt[157], 13}*) This seems ...
9
votes
5answers
2k views

How to find rows that have maximum value?

Suppose if I have following list { {10,b,30}, {100,a,40}, {1000,b,10}, {1000,b,70}, {100,b,20}, {10,b,70} } How to find rows that have max value in ...
4
votes
1answer
558 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 ...
7
votes
1answer
240 views

How to get all possible orderings (equal ranks allowed) for given set of $N$ objects?

Hope there is a solution besides the tedious generation of nested loops. (Trying to avoid reinventing the wheel.) Here is an example with $N = 3$ objects. There are $13$ needed orderings (first ...
1
vote
1answer
61 views

How can I sort the polynomial by the degree of $x$

f1 = a x^2 + b x + c + x^3 (* a x^2+b x+c+x^3 *) f1 /. x -> (x - a/3) // Expand (* (2 ...
6
votes
1answer
281 views

Efficiently searching a list for the position of the closest number to a specified number

Searching by closest and position I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns ...
0
votes
1answer
121 views
3
votes
3answers
184 views

Properly ordering the output of FileNames for a directory consisting of files with consecutive integer names [duplicate]

Say I have a number of files in a directory at some location (C:\dir1\dir2\dir3...), and I pull an array of strings corresponding to the file names with the command: ...
12
votes
1answer
407 views

Is there a “precedence table” for the canonical Sort ordering?

This answer in which I wrote about the Operator Precedence Table was unexpectedly popular. That got me thinking about similar things, and I am wondering: Does an "ordering table" exist for the ...
7
votes
2answers
273 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
2answers
258 views

Sorting a matrix alphanumerically

Somewhat related to Sort matrix by columns and rows without changing them, but more general. I'd like to sort a square matrix (a 3 by 3 in my case, but surely the general solution will treat any), ...
8
votes
4answers
445 views

Gather list elements by index

The following list has some elements that are labeled. For example {1, 2} -> 1, {-1, 3} -> 3, etc: ...
14
votes
1answer
233 views

Ordering function with recognition of duplicates

Fairly often I have a need to get the Ordering of an expression but with recognition of duplicates. For example: ...
0
votes
1answer
90 views

Ordering under assumptions

I have a three-element list which contains inverses of a function u, like so: ...
9
votes
2answers
194 views

Why does Sort fail in this simple example?

I'm sure I'll be embarrassed by the answer, but I don't understand why I get the following result: list = {{9, "b"}, {4, "a"}, {7, "k4"}, {6, "k3"}, {5, "w"}} ...
13
votes
6answers
592 views

Sort+Union on a list

Probably this is too trivial question for this forum but for some reason I am not getting it on my Mathematica 7 so far. I have a list ...
0
votes
1answer
158 views

Sorting a list of triplets by first element of each triplet fails

In the last line of code, I´m trying to order the matrix by the first column. I want to store in the Array t2tlistsorted ( 100 x 3 ), but I can´t. ...
3
votes
2answers
111 views
18
votes
3answers
355 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: ...
-1
votes
1answer
111 views

Sorting the element in a PDB text file

I am a new user of Mathematica and currently using version 9. I want to rearrange the element of one PDB text file with respect to another PDB text file. Suppose I have a PDB file like this: ...
0
votes
1answer
171 views

Using Sort vs SortBy

So I have two lists, A and B. I put them into lists = {A,B}I want to sort A such that Im[#1]<Im[#2]& which I can do fine ...
8
votes
1answer
184 views

How to tell when a job is too big for the pattern matcher?

Pattern matching is great but it has its limitations. Consider sorting a list of numbers from smallest to largest: ...
2
votes
1answer
448 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 ...
2
votes
2answers
283 views

Position function not always retuning 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 ...
6
votes
3answers
507 views

Order list of monomials by degree (Pascal's Triangle)

Suppose I have the following list of monomials: {1,x,x^2,y,y^2,x*y,x^2*y,x*y^2,x^2*y^2} How could I manipulate it to get ...
8
votes
3answers
270 views

Retaining and reusing a one-to-one mapping from a sort

Imagine I sort the elements of an array $Q$ by some means. Perhaps I sort strictly by the elements in the first column, perhaps I use SortBy[...] to sequentially sort by the elements in successive ...
2
votes
1answer
110 views

Confused behavior using Dispatch to sort one list relative to another

I have a need to sort the entries of one list into the same sequence as the entries in a reference list. Because I have rather large lists involving strings, I'm trying to use Dispatch to accomplish ...
12
votes
5answers
1k views

Sort date list in format DD/MM/YYYY

I have a list of dates (ranging from 2007 to 2012) in the DD/MM/YYYY format and I need to sort this list. My problem is, when I simply use Sort[] I get: ...
9
votes
1answer
299 views

Sorting function for non commuting bosons

I am trying to write a sorting function which will sort expressions involving products of bosonic objects which do not commute. For example, I can have objects like $a,\ a^\dagger,\ b,\ b^\dagger$ ...
4
votes
6answers
270 views

Sorting Matrix elements

I have matrix in as shown, consisting of real numbers and 0. How can I sort it to become out as shown? ...
1
vote
1answer
271 views

How to Sort on row by row basis?

Say I have matrix how to sort on row by row basis to get:
5
votes
1answer
219 views

Why can't I remove Orderless from Plus?

I am making some random algebra equations, and I want to have the ordering be random too, such that if my random equation generator makes x+1, the output stays ...
4
votes
2answers
160 views

Sorting list with variable

I want to sort (or sortby) the list. List contains uninitialized variable m and I can assume that m is a Natural number that is much larger then any constant. ...
9
votes
1answer
269 views

Ranking Function Allowing for Ties

I have a list that I need to be able to assign ranks to individual elements in, giving it a number related to its position if the list were to be sorted, allowing for ties. For example, ...
6
votes
2answers
319 views

Merging different size, different order table

I'm a beginner in Mathematica, so this may be a simple request. I have generated some columns of names and data. I want to merge them into a single list of names, with a column for each attribute. ...
18
votes
11answers
1k views

Generating an ordered list of pairs of elements from ordered lists

I have a pair of ordered lists. I want to generate a new ordered list (using the same ordering) of length n by applying a binary operator to pairs of elements, one from each list, along with the index ...
4
votes
2answers
327 views
17
votes
2answers
625 views

Ordering problem

Let's look at the following example. Ordering[{0, 20 Sqrt[5], 40 Sqrt[5], 20 Sqrt[5], 20 Sqrt[10]} // N] gives the right answer ...