# All Questions

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135 views

### Collect data points in a list into weekly groups?

Consider data of a format such as ...
44 views

### Function works outside For loop but not inside, and loop fails spectacularly

I'm building two lists, each to carry a different representation of the same set of objects. One list, list2, is constructed first; then the second list, ...
33 views

### Defining a function that modifies a list [closed]

I have the a list A and I want to define a function f that takes out the $i$-th element from the list ...
169 views

### Finding the index of an element to be inserted in a sorted list

I have a sorted list with no duplicates: L = {1, 2, 5, 7, 8} Given an integer n, I want to find the index of ...
271 views

### How to generate all commutative pairings of list elements?

Given a list with an even number of elements, e.g. list = RandomSample[Array[e, 20]]; how can one generate a list of all different commutative pairings of the ...
184 views

### Efficiently merge lists chronologically without duplicates?

Prepare some dummy data to investigate: ...
38 views

### Tracking back a variable corresponding to an output

I have a function: ...
715 views

### Flatten not working

I am trying to modify some code proposed here Part assignment is not a symbol and I cannot manage to make Flatten work. I write ...
44 views

### Why is this iterative process with matrix calculation so slow?

I am trying something similar to the following code with Ntime as large as 100 or so. Now it's very slow as shown by the Ntime=3 ...
110 views

### Find non-case sensitive string in a mixed list of elements?

Consider an example list with mixed element types, e.g.: list = { 1.234 , a[2] , {"Abc" , 4/5} , "acb" }; I would like to have a function that finds the position ...
60 views

### Nested Do loops with externally defined iterators [closed]

I want to be able to define a set of iterators for nested Do loops, such as ...
170 views

### Simulating ndgrid function of MATLAB

I know that there has been an answer on meshgrid function of MATLAB. For functions involving more than 3 variables, this function does not work. In MATLAB, the ...
351 views

### Replacing the Zeros of One List by the (i-1)th Element of Another List

My goal is to replace the zeros of one list with the (i-1)th element of a second list. For example, if list1 = {0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0} and <...
67 views

### How to make FoldListIndexed ie FoldList with an index or iterator?

Is there a functional or inbuilt way to add an index to FoldList? i.e.: FoldListIndex[f,x,{a,b,...}] gives ...
105 views

### Truncate a set of lists until a subset of entries matches?

Consider lists of vectors of elements like ...
28 views

### Cut graph at a given edge and return remaining subgraphs?

I would like to have a function that removes an edge from a graph and returns all remaining graphs after the operation. For example for a graph like ...
350 views

### Iteratively strip off simply connected edges in graph?

Consider a set of edges composing a directed graph. For example: ...
140 views

### Select connected subsets of integer pairs?

Given a list of integer pairs such as list = { {1,2},{1,3},{2,5},{1,5},{6,7},{6,9},{4,6} }; What is a quick way to separate the pairs into groups in which every ...
81 views

### Converting a free variable in a pure function into a parameter that can be varied under iteration

Here I am going, as a matter of illustration, make a large string list: l = Characters[WordList[]]; l = Table[DeleteDuplicates[l[[i]]], {i, Length[l]}]; This ...
120 views

### Jaro distance in MMA

I'm trying to program Jaro distance as requested by this page I've done the following code that works well for the next two pairs ("MARTHA", "MARHTA") and ("DIXON", "DICKSONX") but when I try with ("...
157 views

### How to calculate linear conflicts on a board?

Thanks to your help to solve previous problems, I have been able to advance in the learning of mathematica. It seems that this project to make a solver for the 8-puzzle has surpassed my abilities in ...
295 views

### How to build these functions without nested For loops?

I am trying to solve the 8-puzzle using two heuristics, which are: Pieces out of place and Distance Manhattan. After consulting several websites for example see and some books, I'm with some doubts, ...
36 views

### Having Trouble with CountryData [EDITED]

I have a list which I call by countryExportPartners = Table[l = CountryData[][[n]]; {l, CountryData[l, "ExportPartners"]}, {n, 1, Length[CountryData[]]}] I ...
44 views

### function over list with condition

For a fake function like: fun[x_] := x^0/x!; and list: list={0,0,0.1,0.2,0.9,0.8,0,0}; It will get error in this way cause ...
62 views

### Plot of a data list evaluated with other function [closed]

I want to evaluate a function of "two" variables using some data points (x,y(x)) (but one of them is related to the other) that I have made with the function Table. ...
104 views

### Efficient way to partition list of expressions based on its contents

I have a list of polynomials polys linear in a set of variables vars. How do I partition the list based on successive dependence ...
49 views

### Separate list elements into groups of two in all possible ways? [duplicate]

Consider a list with an even number of elements, e.g. list = {1,2,3,4}; I would like to have a function fun that produces all ...
41 views

### How to apply a recursive function to a list [closed]

With a list of parameters list={a,b,c,d,e} How can I apply a function f to obtain ...
1k views

### Number of sign flips in list?

Given a list of signs: list={1,1,-1,1,-1,-1,1,1,1,-1}; how to most conveniently and quickly determine the number of sign flips in the sequence? I have this ad-...
114 views

### Building a matrix function one element at a time

I would like to define a function which produces an $N\times N$ matrix where each element is a function of the input values ($N$ is a fixed constant). However, each element of the function needs to be ...
65 views

### Create matrix from combinational arrangement of vectors

I am just trying to produce a short hand code which shall do the following: I have a function of 2 vectors $f(\vec{v_1},\vec{v_2})$ f=#1^2+#2^2-#3-#4&; and ...
134 views

### Tower of Hanoi list of disks on the rods

I'm currently trying to finish a program that outputs the "radius" of each disk on each rod in lists. I currently wrote this program: ...
124 views

### Listwise “summation”, replacing empty lists with non-empty ones and ignoring “sum” of non-empty lists

Given two lists of equal length, l1 and l2, both consisting of sublists that are either empty or non-empty - but corresponding ...
779 views

### What is the elegant way of applying function to two lists?

I am interested in finding the most concise elegant way of doing the following: We have a function fun[x1,x2] and two lists: ...
146 views

### Generate all dihedral transformations of a matrix?

Given a matrix, e.g. matrix = Table[a[i, j], {i, 1, 3}, {j, 1, 3}]; I would like to have a function that takes matrix as ...
112 views

### Finding total distance between a point and all points in a list?

I am looking for the total distance from each point in a list to all points in a another. Specifically from each point in Asubopt to every point in ...
36 views

### How to use Apply and Map properly in this situation? [duplicate]

So this does what I want: #1 <> #2 &["♠", "A"] ♠A The output is fine. How do I quickly apply this to the list ...
53 views

### Efficiently transform sequentially generated integer matrices into boolean matrices

Assume you have a list of 5 numbers, eg L = {14, 7, 11, 14, 0};. Now, what you want to do with this list, is to transform each entry into eg a binary list, using <...
261 views

### How to append functions to a list of functions?

[This question has been rewritten] To simple down my last question, I think this example will be more clear. Suppose I have this list of functions list1[a] and append them to another list of ...
488 views

### Converting integer to a triangular array

I've been trying to write a function toTriangle which converts a given integer to a triangular array. For example: ...
56 views

### Condition on the index of an element $a_{i,j}$

This question may seem to be easy. But I did not find the right way after several attempts I need to put a condition in general for $a_{i,j}$ ,If the i is bigger ...
255 views

### Group by Lengths of Lists [duplicate]

Let’s say, we have a list of lists: Table[0, {30}, RandomInteger[{1, 5}]] which might look like this ...
81 views

### Cyclically sort lists with some repeated elements? [duplicate]

This is a continuation of this question. In the previous question we got a routine that can take two cyclically equivalent lists and determine their equivalence if all the elements in each list are ...
333 views

### Depth function that counts number of nested lists

I'm looking for a function that gives the depth of nested lists in an expression. I do not want to include contributions from things like f[1]. Depth does do this. ...
696 views

### intersection between two 2D arrays with labeled data is slow

Here is how to Generate data the function is below with two images to generate data img1 img2 ...
70 views

### Extracting Data from For Loop

I want to add phases in for loop and after adding a new phase I want to export this data? How can I do this? Can you show me where I do wrong? ...
192 views

### A function that accepts a list of pairs and adds new pairs that are the averages of the neighbouring pair values

Probably a duplicate, but it isn't easy browsing through list-related questions. I am looking for an elegant way to construct a function that accepts a list of pairs, for example ...
766 views

### Can we intelligently control evaluation in Thread?

This is a bid at creating a canonical Q&A. Many questions have been asked that come down to the fact that Thread evaluates its first argument before threading ...