# Tagged Questions

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

389 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 ...
109 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 ...
371 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 ...
175 views

### Sorting out atom types in an XYZ file

I am trying to rewrite the output of "VertexCoordinates" such that instead of a hybrid list of atoms and coordinates that result from using the following input program, I want all coordinates of the ...
417 views

### Sorting an Array with words in different languages

Array consists of words of different languages. I need to sort elements in reverse alphabetical order and make a list of elements, which consist of english letters. Example of array which consist of ...
205 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.
834 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 ...
247 views

### Multicolumn sorting with ordering functions and precedence

I am aware that the question of "how do I sort on a column" has been asked in various forms, most notably this one. While some powerful solutions have been presented, as far as I can find no one ...
264 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 <...
334 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? ...
311 views

### How to pick out the element in a list of lists which satisfies a particular condition?

I have got a list: ...
495 views

### How to sort my list?

For example I have two lists of such structure L1 = {{"Australia",a1}, {"USA",a2}, {"Norway",a3},...} L2 = {{"Russia",b1}, {"Norway",b2}, {"Japan",b3},...} I ...
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)?
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 ...
930 views

### Ordering the Boundary points of a Polygon

I feel like this should be simple, but I keep running into walls. Say someone gives you the coordinates of the vertices of a pentagon and the center point of the hexagon. Is there any way to get an "...
381 views

### Mathematica list element sort

I have a list, say, ...
329 views

### Counting number of inversions

Is there an inbuilt method to find the number of inversions in a set of numbers? I found Inversions in Combinatorica but when I ...
192 views

### Sorting a list and finding an array of indices that sorts the list

How can I sort a list and also get a list of indices that sort this list? For example: primary list is a a={1,4,6,7,0,2}; sorted list is b ...
59 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 <...
183 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. ...
180 views

### Order imported files by their alteration date

Probably a very easy question, but I could not find the answer, so it would be very nice if you can help me: Let us say I have 10 files, all with the extension .dat...
106 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,...
74 views

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290 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), ...
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. ...
335 views

### Import multiple files from folder in order of date added

I have a folder that contains certain files I want to import. In my case those are .png files. As all the files I want to import contain the phrase "accum" in their filenames, I can use ...
138 views

MWE: ...
394 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 ...
323 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: ...
122 views

### How to get the ranked order

data = {33, 6, 10}; Ordering[data] (* {2, 3, 1} *) What I really want is, 3 for 33, as it is the 3rd, if sorted; 1 for 6, as it is the 1st, if sorted; and 2 for ...
125 views

### Non-canonical re-ordering of nested lists

I have some data in the form: ...
85 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 ...
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 ...
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 ...
86 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/...
91 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: ...
296 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 ...
381 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 ...
244 views

### What is wrong with my user-defined ordering function?

I've defined ordering function: myOrderingFunction[arg1_, arg2_] which always return True or ...
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, ...
84 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 ...
111 views

### Find list item before first negative value [closed]

If I have a list like this: ...
102 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 <...
217 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 ...
337 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 ...
116 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 ...
543 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 ...
699 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 ...