Questions tagged [list-manipulation]

Questions on the manipulation of List objects in Mathematica, and the functions used for these manipulations.

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0
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1answer
78 views

correct use of the command FindInstance

I have tried to solve this system for numbers that go from 1 to 10 non-repeated integers, this occurs to me ...
1
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1answer
30 views

Counting the number of occurrences of specific values in a list in specific intervals

If the variable "digits" contains 10,000 digits from 0 to 9. How can the number of occurrences of 1s and 2s be counted in every 1000 digit intervals, that is to say the number of 1s and 2s ...
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8answers
4k views

Finding the period of an array of integers

A simple array of integers is given. The problem is to detect if a pattern is repeatedly occurring in the array, and find the length of that pattern. For example, for ...
3
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2answers
56 views

Building a matrix from the columns of others

A is a n x m matrix, B is a matrix p x m, I wish to build C from appending the ith column of A and ith column of B, for all i ...
3
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1answer
70 views

Using DateListPlot without connecting dots

I have a list of values like this: When I plot this data using DateListPlot[data] I get a plot connecting the individual points such as: My question are: How can ...
9
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2answers
56 views

Use Cases with empty cells in the list

I work with a complex dataset. The most simple form of this list looks like: dat1 = {{a, b, c, {}}, {d, e, f, {1}}, {h, i, j, {2}}} I want to select the nested {} ...
3
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3answers
97 views

Find rules for the similar “Conway's Game of Life”, and initial input on an 11x11 torus board. Descripted on the “Puzzel Chalenge IBM May”2020"

I solved on May 2020 this using mma . I am aware of this command - Cellular automata. But I can't use it on this challenge, because there's no concept of "Torus" in the CellularAutomaton . ...
16
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7answers
1k views

Find second largest elements in list

Given a list: lis = {37.21, 37.21, 37.2, 44, 44, 44, 101, 101} What is a simple way to extract the second largest elements? ...
0
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1answer
135 views

Fast way to count distinct pairs of integers

I have a association list, S, whose size is about 5*10^4. I also have a function F which takes in ordered pairs of elements from S, and spits out ordered pairs of integers. There is some amount of ...
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0answers
26 views

Thread::tdlen: Objects of unequal length in {{a,b,e},{c,d,f}} {x,y,z} cannot be combined

When I do the Times operation among list like this {{a, b, e}, {c, d, f}}*{x, y, z}, the error message is given as Thread::tdlen: Objects of unequal length in ...
2
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1answer
55 views

Finding points located in a specific locations of a 3D objects

I have the following list of points in 3D and would like to find the points which are located on the lower edge of the object and on (or closest distance to) the X-Y or Y-Z plane of the symmetry. (...
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1answer
53 views

How to manipulate solution outputs that appear in a list? [closed]

I have a list {E, {p, ϕ}}, and I need values E, p, and ϕ ...
4
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3answers
158 views

How to select radicand

Given t1 = {1, Sqrt[2], Sqrt[3], 2, Sqrt[5], Sqrt[6], Sqrt[7], 2 Sqrt[31], 3, Sqrt[10], Sqrt[11], 2 Sqrt[17]}; I just want to get all radicands, which would yield <...
1
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1answer
31 views

Exporting Nodal Surfaces/Minimal Surfaces as any 3D source (obj,stl,mb…)

I have been trying to export the surfaces that I gathered in the Wolfram Mathematica application, So is there any way to export surface this to Maya,Cinema 4D, Rhino , or any 3D environment for 3D ...
2
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1answer
97 views

Finding lower boundary of a 3D object in list format

I have the following point list and would like to find the points located in the lower boundary of the 3D object (It is part of a body torso). https://pastebin.com/L12n0Gfr I am using the following ...
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0answers
56 views

Find a sublist with closest X and Y to a specific point in 3D

I have the following list of points and would like to know how I can find the sublist (i.e. point) which has a closest X and Y value to the X and Y value of a specific point (e.g here b1 ={{-20.6105, -...
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6answers
729 views

Partition list into $n$ sublists

Is there an inbuilt function/option or an elegant composition of functions for partitioning a list into exactly $n$ sublists? I played around with Partition and its ...
0
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1answer
41 views

How to change a list of values into variables? [closed]

I have a list {E, {p, ϕ}}, and I need values E, p, and ϕ ...
0
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1answer
56 views

Plot 2D into discrete 3D [closed]

I want to do a 3D plot of this functiony[x_, r_] = -Tan[r] x where I get a set of lines evenly distributed on the r axis, with a discrete distribution. This is what ...
6
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5answers
291 views

Select lists where last elements are identical

Given the following list t1 = {{5, 5, 50}, {6, 1, 37}, {6, 2, 40}, {6, 3, 45}, {7, 4, 65}, {7, 6, 85}, {8, 1, 65}, {6, 6, 72}, {7, 1, 50}}; I want to find those ...
1
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1answer
30 views

Replacing a submatrix of a matrix

Minding the fact that In[102]:= {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}[[1 ;; 2, 1 ;; 2]] Out[102]= {{1, 2}, {4, 5}} is the upper left submatrix. I would like to do the ...
0
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0answers
36 views

Binning of numerical 2d function [closed]

I have a set of data {x_i,y_i,z_i} organized as 3-member sublists in a large (~4000 sublists) list. The z_i are functions of (x_i,y_i): z_i = f(x_i,y_i), but the function f is known only numerically. ...
3
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2answers
294 views

How to drop points that don't lie in a line

I have some data like: ...
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2answers
40 views

Substituting values from an association thread into a table of expressions

I have asked a question here. Yet I am trying to do the same procedure with AssociationThread Suppose I have the following function which is a normal distribution: <...
5
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1answer
45 views

Substituting elements of lists into an expression

Suppose I have the following lists, as = {1, 2, 3, 4}; bs = {10, 20, 30, 40}; and the following expression: ...
4
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1answer
77 views

Thread and RandomReal

I am trying to use Thread to apply a function involving RandomReal but it does not work as I expected. If I have the function <...
1
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1answer
85 views

How to use Quartiles to work the same as TI-83 calculator? [closed]

The statistics book I am using defines quartiles the same as Method 1 explained in wikipedia. Use the median to divide the ordered data set into two-halves. If there is an odd number of data points ...
5
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3answers
348 views

How to classify an ordered ascending {0, 5, 5, 10, 19, 22, 23} into several classes {{0,9},{10,19}, …}?

I attempted to classify an increasingly ordered list into several classes to make frequency distribution table. I am faced with a difficulty to nest two pure functions: one for ...
0
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1answer
52 views

How do we list all points in the Middle $3/7$-th Cantor Set?

Suppose we were to list all points in the $3/7$th Middle Cantor set where we first remove $3/7$th of $[0,1]$: $$[0,1/7]\cup[2/7,3/7]\cup[4/7,5/7]\cup[6/7,1]$$ then $3/7$th of remaining intervals, $3/7$...
4
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3answers
86 views

How do you reorder a sublist of strings, within a list?

I have a list that looks like this: ...
2
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2answers
107 views

How to program a situation like the following in mathematics and generalize the process to other configurations?

Distribute the numbers from 1 to 10(view image) so that the sum of each row and each column is the same and a) the maximum possible b) the minimum possible (I put it from 1 to 10 for ease) I know it ...
5
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1answer
83 views

How do you take position “x” in multiple sublists to make a new list?

this is a rather rudimentary question, but I was wondering if there are more efficient ways to do the following: dd = {{{12, 3, 5}, {14, 10, 11}}, {{15, 76, 65}}} ...
1
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1answer
36 views

Precisión of the numbers inside a list

I'm trying to become a List like this list={1.34,2.64,5.098,6.432} in a list where the numbers have precision of one digit, like this ...
21
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8answers
3k views

Shuffle product of two lists

I want to do the following: I have two lists {a_1,...a_n}, {b_1,...,b_n} and I would like to build now all shuffles out of this. This means all unions of these ...
3
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4answers
153 views

Operation on the first element of list only

If I have the following list: ...
9
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2answers
2k views

How to optimally solve and generalize this Conway's Game of Life puzzle

I tried solving this using mma. I am aware of this command - Cellular automata. But i don't want to use that coz then there is no challenge. So below is how i did it and my question is can this be ...
4
votes
4answers
325 views

How to find the smallest position of an element of an ascending list {1,4,10,12,20} such that the element is not less than 11?

Assume I have an ordered, ascending list {1,4,10,12,20}. I want to find the smallest position of an element of the list such that the element is not less than 11? ...
2
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2answers
59 views

How to select parts of a (non)function

I have a set of points ...
7
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2answers
2k views

All possible topological orderings of a graph

TopologicalSort[] returns one of many unique orderings. From wikipedia: if a topological sort does not form a Hamiltonian path, the DAG will have two or more valid ...
4
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2answers
83 views
3
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1answer
63 views

How can I iteratively add elements to a list

Basically I want to make a histogram with a list of dates by using DateHistogram[]. However I have the data of the dates in nested list format, with elements like ...
6
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3answers
106 views

How to get elements corresponding to UpperTriangularize

For a generally non-square matrix M, I want the upper triangle that include the diagonal entries. Specifically, this is implemented via UpperTriangularize: ...
5
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2answers
97 views

How to permute elements in a list

I am attempting to decrypt a ciphertext. I split the cipher into blocks of five, and now I want to permute each individual block. My goal is to be able to permute each individual block by the same ...
12
votes
1answer
921 views

Is there any better way to create {a, a, a, b, b, b, b, b, c, c} from {{a, 3}, {b, 5}, {c, 2}}?

My attempt: data = {{a, 3}, {b, 5}, {c, 2}}; output = Table[#[[1]], #[[2]]] & /@ data // Flatten {a, a, a, b, b, b, b, b, c, c}
0
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1answer
47 views

How can I add a different value to each item in a list?

I am trying to decrypt a modified Vigenère cipher text. I am unfamiliar with Mathematica, so I need some guidance. Here is what I want: ...
1
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4answers
743 views

Percent Difference between elements from 2 matrices

If i have a 22 by 25 table of values which depend on n and r, and a list of values that depends on r that is a 22 by 1 matrix, how can I find the percent difference between each element, by row in the ...
1
vote
1answer
45 views

Scan and Set over multi-dimensional data

Suppose I have the following: Table[x[i,j] = f[i,j], {i,1,10},{j,1,10}]; I want to set variables x[i,j] to have value ...
6
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1answer
366 views

Why can't I create {a,a,a,b,b,b,b,b,c,c} from x={a,b,c}; f={3,5,2}; Thread@Table[x,f]?

ClearAll[x, f] x = {a, b, c}; f = {3, 5, 2}; Thread[Table[x, f]] produces Table::nliter: Non-list iterator f at position 2 does not evaluate to a real numeric ...
3
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3answers
378 views

Inserting an integer into a sorted list

I'm wondering if inserting an integer into a sorted list (in a way that the list remains sorted) can be performed in Mathematica in some fancy way in $\log(N)$ time?.. The question was asked here, ...
2
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3answers
33 views

Appending a list into another list at various levels [duplicate]

I have a list with three levels. list = {{{7, 5, 8}, {4, 8, 9}, {7, 0, 1}, {3, 0, 4}, {5, 1, 2}}}; And I want to put in a list {e,x,y} at the end of every element. ...

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