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

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2
votes
3answers
57 views

Find position avoiding For loop

I have a list: {a,b,c,d,e,f} And a function sizeFunc[element_] which returns the size ...
2
votes
1answer
35 views

Dropping rational coefficients

I have a list of expressions (they all are exact numeric quantities, not containing any variables), some of them have integer or rationals coefficients, or complex coefficients with rational or ...
1
vote
0answers
27 views

Accessing the elements of a list of values [on hold]

I have a list of polynomials (all with the variable x) called lyle and a function that accesses this list and evaluates it at ...
2
votes
2answers
93 views

Replace elements in some region in a list

I want to replace some elements in list. Assume that we have A={{1,2,3,4}, {5,6,7,8}, {9,10,11,12}, {13,14,15,16}} and we want to replace elements ...
1
vote
1answer
41 views

Sort and Save Matrices Eigenvectors to a Larger Matrix

We are going to sort and save all orthoginalized-eigenvectors of 4*4 random matrices (produced in any iteration) to a larger matrix such as storagematrix. Since, produced random matrices are 4*4, ...
0
votes
1answer
59 views

Match a variable name pattern [duplicate]

I have a list of variables: {RBI,RCD,ASD,FGH} I want to select only those whose name starts with R. Using the pattern Rx_ ...
2
votes
3answers
110 views

Join nested lists based on first and last elements within each list

I have a nested list like this: test1 = {{1, 3}, {1, 4}, {1, 7}, {2, 1}, {3, 5}, {4, 1}, {5, 2}, {6, 1}, {7, 6}} I want to join the lists together depending on ...
0
votes
0answers
36 views

sum and infinity [on hold]

I posed this question a few days ago that is no answer, but now I will clarify. If you have the sums $ (1+2+..+n) + (1+2+3+..+n-1)+ (1+2+3+..+n-2)+(1+2+3+..+n-3)+...+(1+2+3)+(1+2)+1$ for large ...
0
votes
2answers
49 views

Identify a scalar, a list

I have a symbolic scalar m2 and a symbolic list (representing a 3x3 matrix) A. I want a function which does something like: ...
1
vote
2answers
59 views

Convert a list of lists of rules to a list of values [closed]

I have a list of the following form: thisVeryExcitingList={{x->1},{x->2},{x->3}} I would like to convert it to the form ...
3
votes
3answers
149 views

Move element inside a list

I need to change the position of a single element in a list. Example: I start with: {a,b,c,d,e,f} I want to move the a before ...
0
votes
0answers
45 views

Programming style for destructive modifying array arguments [closed]

ReplacePart[] returns a new array, leaving its array argument unmodified. a={{1,2},{3,4}; ...
7
votes
4answers
222 views

Improving a selection routine

How can this code for extracting the smallest (absolute) real value be improved? and would it be simpler using associations? ...
-1
votes
2answers
66 views

Delete Element within a List based on the Order [closed]

I want to do the following, deleting the element of a list that do not match an increasing order as example: {1,2,3,4,6,5,7,8}->{1,2,3,4,6,7,8} I've thought of using DeleteCases but I'm not able to ...
0
votes
3answers
73 views

Do not expand matrices in Mathematica calculation

Here is an example of a problem I'm having. Consider that I have defined: omega={{p[t]},{q[t]},{r[t]}} x={{a},{b},{c}} R={{1,2,3},{4,5,6},{7,8,d}} What I would ...
0
votes
0answers
25 views

How to show different DateListPlots with a popupmenu with different plot parameters

I bumped into the following problem: I have a relatively large dataset (250k row,11col), imported in from an SQL database. The format of the data is {{year,m,d,h,m,s},value}. I have successfully ...
0
votes
0answers
35 views

Creating multiple plots from multiple lists [closed]

I'm having trouble creating a series of list plots from a set of lists. I have 19 lists and I would like to have 19 Listplots. Here is an example of what i've got now: ...
2
votes
3answers
486 views

For loop in Length computation code

Here is a code I wrote that is supposed to give the length of list after some splitting and regrouping. But it is inefficient. Is there a way to rewrite in more professional and efficient way? I guess ...
0
votes
3answers
50 views

Dynamic insertion of variables

I have a list of eigenvectors of a given matrix. I need to programmatically modify this list by multiplying each vector by a variable #i, e.g. ...
-1
votes
2answers
43 views

Changing the precision of data in a list of matrices

I have a list of matrices ...
5
votes
7answers
424 views

List manipulation challenge

It's necessary to get from list = {{a1, b1, c1}, {a2, b2, c2}, {a3, b3, c3},{a4, b4, c4}, {a5, b5, c5}}; I'd like to do this with ...
0
votes
0answers
32 views

Dot production associated with comparison process of different matrices eigenvectors

With thanks to Guess who in the link module using.. We created functional 5*5 matrices: ...
0
votes
1answer
48 views

Module using for creating a table [closed]

I want to have a 4 tables with using of module. Unfortunately I don't know why doesn't it work ...
2
votes
1answer
61 views

List of list to list of rules

I have a list of this type p = {{y, 1, 3}, {x, 2, 0}, {z, 3, 1/(k + 1)}} I can use a Do loop that is ...
7
votes
1answer
97 views

Converting a Table to a Dataset

I feel like this is a simple task, and there may be a built in method to doing this (but I can't find it if there is). I would like to be able to take a table and convert it into a structured Dataset. ...
1
vote
4answers
104 views

Difficulties with list manipulation

I have a list of five elements. For example, list1 = {a1, a2, a3, a4, a5}; I'm trying to get a list: ...
0
votes
0answers
20 views

Specifying plot markers (filled diamonds or squares) [duplicate]

I can plot my list data and I can use of specifying circle to show my plot-markers. I used of Mr.Wizard comments on that page. But I don't know how can I fill the circles of those plot-markers with ...
-2
votes
3answers
82 views

Applying a function to a list with fixed intervals and fill the resulting list [closed]

I want to apply a function f to a list with fixed intervals, and then fill the gaps of the resulting list, as shown in the following picture. Since it will be run ...
1
vote
1answer
52 views

Adding another looping element with a list

I have code that is looping on to elements and is working shown below ...
3
votes
1answer
42 views

Use a part specification as the argument to a compiled function

I have some code that needs to generate a large matrix based on some complicated combinations of smaller matrix elements. I find that if I write a function for the element of the larger matrix, and ...
2
votes
1answer
62 views

How to solve an equation given certain parameters?

I am new to Mathematica so please bear with me. I have an equation that has around 7 parameters and one unknown. I was able to use FindRoot to solve it; however, I ...
5
votes
3answers
207 views

how to concatenate a list of a list of strings

I have two lists of lists, La and Lb that I want to concatenate so that every element of a list n in La is concatenated with the corresponding element of list n in Lb. For example: La = {{P, O, O, ...
2
votes
1answer
104 views

Why is there a difference when formulating patterns for Select and FirstPosition?

Select[{1, 2, 4, 7, 6, 2}, # > 2 &] Gives {4, 7, 6}. OK! So one should think that the following would work: ...
2
votes
0answers
28 views

Basic Question: Split Nested list into respective elements [closed]

New to Mathematica, just have a very basic question to ask. I have a table of results like so: ...
2
votes
3answers
111 views

Given a list of triangle vertices, how to find the neighbors for each vertex?

A triangle is represented by {a,b,c}, indicting that its vertex IDs are a, b, and ...
1
vote
5answers
124 views

Select using MemberQ

I want to make a selection on this list ...
0
votes
2answers
57 views

Company headquarters for each cell in a spreadsheet

I have an Excel spreadsheet column with hundreds of company names on it. I need to find the address (or just city if that's easier) The operation for this is simple in wolfram alpha. i.e. typing ...
3
votes
6answers
548 views

How to smooth the noise

This is a sample data ...
0
votes
1answer
29 views

Creating a custom list [closed]

This is the first list lts1 = Table[i, {i, -1.8, 5.8, 0.1}] 1st question: In the interval between -1.8 and 5,8 how can I choose the step beforehand so as the ...
2
votes
3answers
66 views

An extra { when importing a file [closed]

I am trying to import data from a file. {k0,{a0,b0,c0},{e0,f0,g0}} {k1,{a1,b1,c1},{e1,f1,g1}} MyList = Import[file, "Data"]; But I get a list with an extra "{" ...
9
votes
5answers
224 views

Find all the possible ways of partitioning a list into a set of pairs of element

I have a list {x1,...,xN} where N is even, and I need to find all the possible ways to split it into pairs of elements, e.g. the ...
7
votes
1answer
99 views

How to select a submatrix containing similar elements from a matrix? [closed]

( This question is related but does not ( fully ) answer my questions. - Finding the position of similar elements in a matrix ) I have not written code yet, I am in the design phase of code for the ...
3
votes
2answers
79 views

Output matrix with common elements

Given lists of lists like a and b, I want to obtain an output like c. a = {{2, 1, 0}, {1, 2, 1}}; b = {{2, 2, 0}, { 2, 2, 1}}; c = {{2, 0, 0}, {0, 2, 1}} If ...
0
votes
1answer
54 views

Applying corresponding elements of a list to a list of functions

I found this post which applying a function to a list of functions and arguments. I thought I could change my code with a table to something more elegant. I am not wedded to the ...
0
votes
3answers
68 views

Confusing “Part::pspec” and “Part::partw” following call to ParametricPlot3D

The problem I'm having is that the function definition given below continually gives me baffling error messages. I'm trying to turn a list of 3D points into a function that approximates a curve by ...
2
votes
1answer
76 views

Using and replacing sequential elements of a list

Very simple question but I am an absolute beginner, so apologies if this has already been answered. I need to pick sequential elements of a list, excluding t=1 and t=T, and use them in a function. ...
6
votes
3answers
172 views

On a strange pattern of triangular numbers in Ulam's spiral

In this MSE post, user GeMir noticed that, where the green dots are the triangular numbers, $$T_n = \frac{n(n+1)}{2} = 1,3,6,10,15,21,28,36,45,55,66,78,91,105,120,136,\dots$$ in the Ulam spiral ...
3
votes
1answer
59 views

Count two or more equal consecutive elements in a list and create histogram

I have a list generated by: list = RandomInteger[{1}, 100] it contains only 0's and 1's ...
1
vote
4answers
92 views

GatherBy output with given Shape

I would like to group items in a binary list according to some property like in the following simple example. ...