# Questions tagged [list-manipulation]

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

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### Find shortest subsequence

We will deal with arrays of chars, but not strings! Let we have the next three arrays: ...
471 views

### How to set to 0 all terms in a matrix which contain a minus

For a matrix like F = {{β , x β}, {-2 β, -3 β}}; F // MatrixForm I would like to set to 0 all terms which contain a minus, in this case the bottom row, getting <...
305 views

### How to plot properly the following data?

Consider the following test data: ...
1 vote
125 views

### How could the whole series of graphics be saved?

I would like to save a series of graphics of a function as pictures. But the problem is that I can't manipulate the name of the graphs, because of that only the last graphics in the series is saved. ...
86 views

### PositionIndex of isomorphic value

The following example is a simplified version of a problem I am working on: equivalent[x_, y_] := Mod[x, 7] == Mod[y, 7] Given a list, say {3, 7, 5} and an integer ...
2k views

### Find Roman numerals up to 100 that do not contain “I"

The question is from Elementary Introduction to the Wolfram Language, section 28 Tests and Conditionals: Find Roman numerals up to 100 that do not contain “I”. What am I doing wrong that the following ...
1 vote
117 views

### How to get DFT from Sound/Audio/Image?

When I'm trying to do Discrete Fourier Transform or just get a ListPlot of values from Sound object, I get error message.. I understand that Fourier command (and ListPlot of course) works only with ...
1 vote
99 views

### How to sort eigenvalues (from minimum to maximum) and their corresponding eigenvectors?

When using NDEigensystem, the first eigenvalue corresponds to the first eigenvector, the second eigenvalue to the second eigenvectors, and so on. I would like to sort the eigenvalues from min to max, ...
90 views

### Multiplying a certain column from a table with a function

I have the following list of matrices whose second entry I would like to multiply/divide with a function, say f, and store the resulting table as a new table. How should I go about doing that? Thanks *...
1 vote
74 views

### Separate the elements of a row [closed]

I have a $\psi$: {a,b,c,d,e,...} for example for 10 letters. How can I change it in the format: {{a},{b},{c},{d},{e},...} I ...
1 vote
148 views

### How to combine Flatten and Partition? [closed]

In order to get list x4 from list x1, I used three operations. How to get list x4 in one ...
1 vote
99 views

### List manipulation and plotting

I have a code which takes as input RandomSample[Range[d^2],4] for a given d and outputs a value ...
220 views

### How to join two one dimension lists as columns in a matrix [duplicate]

I would like to take a one dimensional list, e.g., list1={1,2,3} and add a second column, e.g., list2={a,b,c} to get ...
133 views

### Plotting two variables from multiple lists

Given a few lists as below ...
61 views

### comparing lists of unequal lenghts

Suppose I have three (nested) lists A , B and Cmat where ...
1 vote
75 views

### How do I find the "edge" values/positions in a list?

I have a list of values and am interested in finding the contiguous region above a certain threshold. I have gotten this far,but cannot seem to find the correct way to find the edges. Note: It is not ...
1 vote
64 views

### How to define the boundary of the 2D region outside of the list of sub-regions?

Consider the following file. It includes a list of tables defining some regions. ...
1 vote
152 views

### How to merge the lines in the following way?

Consider the following curves: ...
185 views

### Finding the sum of eigenvalues of a matrix depending on the parameters

There is a system that has the following Hamiltonian: $H=-\frac{1}{2}\Delta-\frac{1}{r}+\frac{B^2}{8}\rho^2-\frac{B}{2} (m + 2 m_s)$, where $r=(\rho,z,\phi), B=5, m=0, m_s=-1/2$. To find the ...
329 views

### Evaluate a function with two lists and table

I have the following function: f[x_,y_]:=x^2/y and two sample lists (that are actually longer): x={2,4,6} y={3,5,7} I want to ...
1 vote
97 views

### Generate family of linear inequalities from vector variable for use in FindInstance

Suppose that I have a vector variable xvec = Array[x, 10]. How do I generate the family of linear inequalities F = \{ {x\in\mathbb{R}^{10}:x_1\geq x_2,\ldots,x_9\...
25 views

### sum elements (variables) of a vector variable [closed]

I would like to sum elements of a vector variable, e.g., Is xvec = Array[x, 10] s24 = Sum[xvec[i], {i, 2, 4}] where $s_{24}:=\sum_{i=2}^4 x_i$. However, I am ...
1 vote
73 views

### How to group the table in the following way?

Consider the following table: ...
107 views

### How to split the table with different number of columns into those with equal number of columns? [closed]

Consider the following table: tab = Join[RandomReal[{0, 1}, {2, 2}], RandomReal[{0, 1}, {3, 4}], RandomReal[{0, 1}, {2, 3}]] Could you please tell me how to ...
272 views

### On plotting multiple lists

I have four lists as given below: ...
287 views

### Is there a Mathematica function that puts a list of numbers in a normalized [1, 10[ scale

I have the following list: ...
166 views

### How to write a function in the following form f[a_, b_, c_,...] so that it is flexible with respect to the number of arguments?

@lericr have written under several of my questions that the way I try to modernize the code could be made much simpler. Below is the original part of the code. The remaining parts have similar designs,...
454 views

### How can I change the data arrangement in a list?

I have data that, when imported to my notebook, is shown in the form: list = {{1,2,3},{4,5,6},{7,8,9},{10,11,12}} I want to transform this into: ...
85 views

### How to correctly reassign variables {c11 -> p11, c12 -> p12} using a Table or some other similar structure?

Why is the value of the function Pxx[1,2] is a number but the function Pxxx[1,2] is an expression? Isn't this construction ...
81 views

### How to use sequence of variables (Sequence) correctly?

Why does the function EER[1,2] have a different value than the function EERR[1,2]? Isn't the entry ...
75 views

### The correct notation of a function that contains an expression with NIntegrate

I tried to set the function Px[a1_, b1_, qa_, qb_]. Why does Px[1.22, 0.44, 1.40, 1.81] not give out a specific number? ...
41 views

### Table with an angle | rotate the co-ordintae

I have the following, Flatten[MapAt[Reverse, 2]@ Table[{i, j}, {i, 0, 10, 10}, {j, 0, 90, 90}], 1] that gives, ...
759 views

### How to quickly make a rectangular array of continous 1 and 0 given the start position of 1

I would like to make a rectangular array of 1 and 0 with continuous columns of 1. We are ...
602 views

### Check if a string is a date

I have a list of strings, {"BD4675365", "Corp", "Managers", "Syndicate", "2021-03-08", "8434926"} and I ...
35 views

### saving output and ListPlot the output:

Let's say I have x = 1; y = 2; d = x^2 + y^5 ; and x = 5; y = 3; d = x^2 + y^5 ; and ...
1 vote
60 views

### get the first from a list using slots [closed]

Problem. I work with a list and want to get the first element. For specific reasons I want to use # in combination with Map For example ...
49 views

### How to select only particular values from the list using dialog windows?

Consider some list: list = {"A","B","C","D"} How to select only particular values from it using a dynamic dialog window ...
67 views

### 3D plot not working, find max/min points [closed]

Im trying to plot this graph in mathematica: (x+y)sin(x-y) And this is my in- and output: Plot3D[(x + y) (Sin[x - y]), {x, -50, 50}, {y, -50, 50}] The output is ...
86 views

### Select and deselect many options at once in CheckboxBar

Is there any way to select and deselect many parameters in Manipulate's CheckboxBar? For instance, consider following code: ...
76 views

### Speed up compoundReturn across an array

I am trying to calculate a moving-window of compounded returns on a large 2D-array. (ie some kind of MovingMap on geometric returns) The Rows are time-steps and the Columns are different financial ...
322 views

### Delete special part from a list using Mathematica

I have a list like this: {{-0.0019,1},{-0.0018,2},...,{0,11},{0.001,6},...} I need to make a new list that start from zero value. like this: ...
402 views

### A loop in which three indices are changed

How could this piece of code be written in the Table, or as simply as possible? ...
1 vote
84 views

### Automate data entry into the Print

There are a several variables a11, a12, a13,...,a21, <...
1 vote
147 views

### Associating a string variable with a numeric variable

There is a translation operation from a numeric variable to a string variable: a[i_, j_] := Symbol["a" <> ToString[i] <> ToString[j]] How ...
1 vote
163 views

### Generating a table of squares and square roots up to 100

I want to generate a table of roots and perfect squares similar to the image, but I can't find the right code, I have searched the forum for something that works for me without favorable results. Can ...
120 views

### How to correctly specify variables in a function? [duplicate]

There is an expression ...
88 views

### Map, applying list in a defined function

Suppose I have defined some function (This is arbitrary) F[alpha_,a_,b_,c_]:=List[alpha,a+b+c] I want to apply this F for a given huge list of sets ...
1 vote
75 views

### Assigning each string variable to the corresponding element from the list inside a loop

I would like to assign values from a list l to variables g1, g2, ...