# Tagged Questions

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

46 views

### Disabling Mathematica's automatic sort of output

I used Mathematica to greatly simplify an algebraic expression. I now want to copy it into some notes, but it by defaults things in a very non-intuitive manner. I have a sorting function that will ...
230 views

### SortBy misbehaving?

It maybe a stupid thing in the end but I'm stuck a couple of hours now. I have a list of 2 points on the plane and I want to get the one with the biggest second coordinate. I thought I knew how ...
267 views

### Sorting Lists of lists of arbitrary length

I'm trying to sort a list of lists. The sublists are defined in length, but the length of the list containing it varies. A simplified set might be: ...
109 views

### Collision detection algorithm (discrete) with sweep and prune algorithm

For a more complex collision detection approach, I need an efficient (aka fast) algorithm to prune the elements by using boundary boxes. A classical algorithm is the so called sweep and prune (SAP) ...
112 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 ...
153 views

### How to define even permutations correctly?

I define even permutations as following, but there may be some error. I use it in two different way and get different output. ...
245 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 ...
390 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 ...
212 views

### Unexpected behavior when using SortBy as a dataset filter

I am still experimenting with datasets. Recently I tried to query the Titanic example to get info on the oldest passengers. Here is what I tried ...
53 views

224 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 ...
96 views

### Another Sort with multiple criterion

I have a list ...
150 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: ...
270 views

### Sort a list of coordinates by frequency from first component of each coordinate

The situation is that I have a List like this: ...
335 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 ...
238 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 ...
169 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.
79 views

### Ordering under assumptions

I have a three-element list which contains inverses of a function u, like so: ...
187 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"}} ...
351 views

### Gather list elements by index

The following list has some elements that are labeled. For example {1, 2} -> 1, {-1, 3} -> 3, etc: ...
125 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. ...
107 views

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

I have some data in the form: ...