# Questions tagged [list-manipulation]

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

549 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
1 vote
458 views

### ParametricPlot - Several curves by different parameters

I am trying to plot a set of curves f(a,b,t) along t with a,b = -10, -9, ..., 9, 10. I can use Manipulate to draw 1 curve, and then change the curve shape by ...
1 vote
138 views

### Specifying the number of points sampled by NDSolve, and the meaning of "steps"

I am working with lists generated from interpolating functions given by NDSolve. Manipulating the lists, I encountered a problem - the lists, of course, need to be ...
1 vote
79 views

### How to plot data from table dynamically, without knowing how many columns are there?

I'm trying to read coordinates at certain times of Planets and Plot the orbit into a graph. For this example I'm doing this for eight planets, some coordinates from a table of some timesteps of the ...
1 vote
70 views

### Problem using ConstantArray in FindRoot

I ran into a strange problem, where using ConstantArray inside FindRoot results in a ...
1 vote
95 views

### Finding the main phases of the Moon in a particular month

My aim is to build a function that has parameters month and year and returns four lists, namely with the dates of the new moon, first quarter, full moon, last quarter. This is more possible after ...
1 vote
89 views

### TickMarks get different length inside function plotGrid

Mathematica 11.2 or earlier: I want to create a grid of plots and found this one by Jens excellent: https://mathematica.stackexchange.com/a/6882/245 : ...
1 vote
71 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 <...
1 vote
169 views

### Removing zeros from a list of equations

I am setting up a matrix system of differential equations that need to be solved. Some equations are redundant, and I have removed them using UpperTriangularize[]: ...
1 vote
62 views

### Delete duplicates in a list compiled of different lists and also delete

I've got three lists: Lst1 has 100 different values for "r". Lst2 has 100 different values for "a". And Lst3=Pi*Lst1^2*Lst2. In Lst3 I've got duplicates and I want ...
1 vote
180 views

### Proper syntax for DeleteCases with conditions

List is an array of dimensions {61777, 3}. dist1 & dist2 are RegionDistanceFunctions. Using: ...
1 vote
66 views

### Using lists to access tensors like in MATLAB

I have a tensor of a variable size as an input to a function in which I need to access specific elements. Because the order of this tensor is variable, notation: ...
1 vote
132 views

### Computationally Employ Sum over Ordered Partitions?

I have the following function defined, with two inputs $g$ and $h$: ...
1 vote
187 views

### Format of numbers in a list

I wrote the below lines: rang1 = Range[0.0, 0.4, 0.02]; rang2 = Range[0.5, 1.0, 0.1]; caten = Catenate[{rang1, rang2}]; I see ...
1 vote
91 views

### Exporting lists to text files with specific names

I am working with two matrices (because I have more matrices with indices (1,2,3,...) I write them below in specific format i. e. ...
1 vote
209 views

### Extract coefficients from CoefficientRules

So CoffeficientRules[] gives a vector {E1->c1,..., En->cn} for the N monimals Mi in the polynomial P = M1+...+Mi I would like to separate the coefficients ...
1 vote
95 views

### Iterate over values in a table only if they are in a region

I made some pretty simple PDE's in non-square regions, and I am attempting to output the data (t, x, y, funcval) out to a .csv file (I know, terrible format for this, but it was a requirement for the ...
1 vote
205 views

### Fill grid with list data

I have the following list: list = {{114}, {59, 55}, {31, 28, 27}, {17, 14, 14, 13}} The list data should be placed into a ...
1 vote
84 views

### EmbedCode not evaluating a list of Manipulates

I have created a simple FormPage that asks for some user input, and should display a list of manipulates which are influenced by the given input. I use EmbedCode to display my results. The code I used ...
1 vote
72 views

### indexing matrix computation by lists

I have a list of triangles stored as indices into a list of vertices: ...
1 vote
45 views

### Problem with adding multiple tables from imported text file

Im having problems with performing operations on imported files and it is outlined as follows: $1.$ Because of memory constraints on my computer, I used export that saves each iteration into a text ...
1 vote
409 views

### Accessing table extension in FITS file

I have a FITS file here that has no image but simply has a binary table in its extension. I have tried using Import["file","Tabledata"] but it returns an empty ...
1 vote
81 views

### AirportData, GeoNearest and filtering data

I bought a Raspberry Pi, which introduced me to Mathematica, and I'm just diving in. I'm guessing my question is really a basic syntax question, but I don't know how to unravel it. I thought I would ...
1 vote
93 views

### Time-stepping an equation in Mathematica

I have an iterative integral equation of the form n(k,t+dt)=n(k,0)+dt\int_{0}^{\infty}dp\int_{0}^{\pi}d\alpha\int_{0}^{2\pi}d\beta\int_{0}^{\pi}da\,p^{2}q^{2}\sin(\alpha)\sin(a)\frac{(n(p,t)+1)}{\...
1 vote
362 views

### Assigning Values of Indexed Variables to Arrays

New to mma. I have assigned the results of using Solve to solve 5 variables to 5 indices of a new variable: ...
1 vote
45 views

### A problem of presentation of a matrix product inequality

I have 4 vectors or matrix aa = {{a[1,1],a[1,2]},{a[2,1],a[2,2]}} xx= {x,x} bb = {b,b} c = {<=, <=} can I find an operation which gives ...
1 vote
239 views

### Problem with the calculation of Lyapunov exponents

I am trying to calculate the Lyapunov exponents for the orbit of two bodies around each other. Therefore, I use the following code: ...
1 vote
173 views

### Plotting 3d lists with large data sets more efficiently

I have been trying to plot a set of 3D points using ListPlot3D. The list is very large, in fact Mathematica is even taking an excessive amount of time to calculate ...
1 vote
44 views

### NMaximize over a Large List: No Output

I have a list of 500 sublists of the form: ...
1 vote
106 views

### calculate new table from values of old table and find fit model curve

I'm new to mathematica and I'm struggling to figure this out. I have a file with 6 space separated numerical data columns. Column 3 and 4 are the x and y values of the real data, column 5 and 6 are ...
1 vote
53 views

### Arrange of several files

I am struggling to import my data. There are 400 files in CSV format with names organised by date like: Table1_20111003_YYYY_MM_DD_0000.dat. In each file over 20 colums and 86400 rows (seconds of ...
1 vote
40 views

### Partial Sum of Binary Sequence not Working

I have the following code: ...
1 vote
85 views

### List manipulation, averaging over lists and fidelity

I want to create vectors from a function poly[α_, β_, δ_, ϕ1_] were several variables (α, β, δ) are randomly sampled from a unit sphere. Then I want to vary another ...
1 vote
112 views

### Find best convex approximation of an "almost convex" function

I've got values of a function of two variables at integer points inside a rectangle, that is, a rectangular table $f(i,j)$, $1\leqslant i\leqslant m$, $1\leqslant j\leqslant n$. The function is very ...
1 vote
56 views

### Simplify expression?

Suppose I have expressions that involve terms like: p1.p1+p2.p2+p3.p3+p4.p4 p1, p2, p3, and p4 are all elements of an array: ...
1 vote
73 views

### NIntegration and DSolve with same variable

I need to solve this problem: Then follows the code, with: ...
1 vote
53 views

### Using Coefficient for Conjugate[variables] (Mathematica ignores my assumptions)

I have a sum and I use Coeffcient[] to extract certain terms. For example, I want all term in the following sum that contain ...
1 vote
56 views

### Concise use of list addressing

I very often work with Lists of Lists (trend data exported from other programs). Sometimes the start times of the important data ...
1 vote
91 views

### Finding correct combination of functions

I am trying to write code where I have an array $S$ or numbers in any order [5,4,2,1,....] Then I have a specific set of functions that I can write. ...
1 vote
46 views

### Defining an object which is function in some variables and tensor in some other indices

I am trying to define an object which function in some variable and tensor in other indices. My attempt at it was: ...
1 vote
162 views

### Lower memory usage and speed nested loops

I'm trying to make some tracking with Mathematica. ...
1 vote
62 views

### Generate a list of values of a function for each value of the parameters already found

The following question is an extension of this question Find all roots of a function with parabolic cylinder functions in a range of the variable. Now I want to use the roots found to calculate a ...
1 vote
181 views

### Problems with indexes in a Do-cycle and CoefficientArrays

I have a system of linear equations with variables $A_n$ and need its coefficients in a matrix form (Transform linear system into a matrix form). I'm trying to do that through a ...
1 vote
78 views

### Constructing a function for expanding general $n$ products

I have the following quantum mechanically motivated product: $\langle0\vert(A_1b_1 + A_2b_2 + A_3b_3)(B_1b_1 + B_2b_2 + B_3b_3)(C_1b_1 + C_2b_2 + C_3b_3)$, where $b_i$ is an annihilation operator ...
1 vote
295 views

### Tracking solutions over a Brillouin zone

Thanks to @bbgodfrey I have a function that finds the two solutions to a set of equations bounded by a hexagonal region (corresponding to the Brillouin zone). It takes the angle ...
1 vote
158 views

### Disease Network Model Using NDSolve

I have a basic disease model using NDSolve: ...
1 vote
229 views

### Autocorrelation of 3D Points

I'm trying to compute the autocorrelation of a list of points $(x,y,z)$ in 3D. Can the CorrelationFunction or maybe ListCorrelate...
1 vote
79 views

### Make a table of changes in US coinage

I thought of an innovative use of Mathematica/Alpha that I think Stephen Wolfram would really love, but I can't figure out how to get it to work. The idea is to make a table that would chart the ...
1 vote
91 views

### A more efficient way of fitting a non-linear model that returns an entire list?

I have a function that takes two parameters, del and nu, and returns a list npoints long ...
1 vote
How can I automatically generate all possible three-dimensional binary arrays of size $(x_1 \times x_2 \times x_3$) where each array is distinct from all others with respect to rotation and reflection ...