# Questions tagged [list-manipulation]

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

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### Certain search in list

A list $LL$ of $n$ real numbers is given. For each element $e$ of $LL$ to find the position of the closest to the right element of $LL$ which is at least twice bigger than $e$ and return it. If ...
78 views

### Sum with list as its upper limit

Say I want to create the list $\{ \sum_{j=1}^{5} 2j, \sum_{j=1}^{6} \frac{5j}{2} \}$ I guessed that this can be done using the code ...
77 views

### Parallelizing MapAt

What is the best way to parallelize MapAt? Only ParallelMap is provided, but seems bad when executing functions on a subset of a ...
60 views

### Make a function of a list of expressions

I have a family of functions, each of which takes a long time to build the expression. Once the functional form is determined, however, calculations are very fast. So I want to build a table of ...
282 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 ...
47 views

### PauliMatrix tensor product

My Pauli matrices are: ...
171 views

### Select items in a list that contain criteria #2 [closed]

In List: Tuples[{1, 2, 3, 4, 9}, 4] How can I select all items that contain only two "9"? Result: {{1, 1, 9, 9}, {1, 2, 9, 9}, {1, 3, 9, 9}, {1, 4, 9, 9}, {1,...
505 views

### From the list of 3-tuples, how can I select tuples which contain one for more nines? [closed]

From the list Tuples[{1, 2, 3, 4, 9}, 3] how can I select exactly those 3-tuples that contain one for more nines? This is the result I want: ...
51 views

### JoinAcross with multiple associations

I would like to use JoinAcross to combine several lists of associations. Extending an example from the documentation, I'd like to do this: ...
71 views

### Expressing an Edge List as a 0-1 Table with Headers

Consider the edges ...
39 views

### Eliminate date in a list [closed]

I wish to eliminate the dates of my list of BTC prices so that I only have the prices left (I do not need the dates for the purpose of my analysis). The list appears as follows: Is there an easy ...
184 views

### Efficiently merge lists chronologically without duplicates?

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

### Counting the number of duplicates in a list

What is the quickest way to count the maximum number of duplicates in a list? For example, the maximum number of duplicates in {1,1,1,3} is 3, in {1,1,2,2} is 2 and in {1,1,1,2,2,2,3,3} is 3. I've ...
210 views

### Finding x,y coordinates where y is largest

Suppose I have the following list of $x,y$ coordinates: ...
36 views

### Error with combining lists

I'm attempting to combine lists of the form ...
630 views

### Concise way to draw this pyramid

I wrote the following to draw a pyramid, this approach uses functions TranslationTransform and Tuples, is there a way to do the ...
43 views

### Taking multiplicities into account when counting the elements of a list

Say we have a list l = {4x,3y,z} When we do Count[l,x] we get, as expected 0 Is there a function, call it F, that ...
55 views

### How to transpose a data of N lists?

I am using a command like this data = Transpose[{t1, Table[z1[[i]], {i, 1, 10}]}] //Tableform There will be N lists t1,z1[],...z1[] I would like to ...
66 views

### How to make split tables in Join?

I have a command Table0[mS_]:=Table[{mS*i,i^2},{i,1,20}] Table1=Join[Table0,Table0,Table0] When calling Table1[] I expect to get the element Table0...
38 views

### Tracking back a variable corresponding to an output

I have a function: ...
101 views

### How to rearrange the terms in polynomials to the power of x?

Here is my code Eliminate[y == x + n && x^2/6 + y^2/3 == 1, y] I got 6 - 3 x^2 == 2 n^2 + 4 n x But I wanna it to be ...
627 views

### Select row of data if next row contains zero

I am a new user of Mathematica, and just faced a problem. I have a data set of three columns, and want to select only those rows that go before the rows, which contain 0 in the third column. ...
90 views

### How to put solutions of mutiple DEs with NDSolve in table

I have $N$ differential equation for each $s \in {1,2,...,N}$ on the domain $x \in [1,2]$ of the form (e.g.) $xf_s'(x) + \log(xs) f_s(x)+1 = 0$, with the boundary condition $f_s(1) = e^{-s}$ Now I ...
87 views

### Mapping a function f[xi_,xj_] over a list {x1, …, xn} with the i < j restriction

I am often facing the situation where I have a list $\{...x_k...\}$ and where I want to compute: $$\{...f[x_i,x_j]...\}\text{ with }\ i<j$$ Unfortunately, I have not been able to find an ...
57 views

### Import and merge PDF files

I have a folder with several pdf no more than 50, I would like to import them to be disordered and that the output was a single pdf (you can imagine it as a proof of form A and we want to produce form ...
27 views

### Problem with UnitConvert with a list

I'm studying this part of the course units convert I have two list the first: is in Megaparsec and I need to transform it to kilometers ...
53 views

### Pull the data from a set of chosen rows of a table

Suppose I have the matrix shown. Suppose I want the entire row data associated with specified column IDs 106, 110, 109. The output would be {106, Job2, J2},{110, Job7, J7},{109, Job5, J5}. ...
26 views

### Taking tuples of a variable number of lists?

I have a number n lists indexed by i as list[[i]], how can I write a function which outputs all n-tuples of elements in these lists when I would like to vary n?
43 views

### What is the number of contiguous subsequences in this binary word?

I want to count the number of times the contiguous sublist 0,1,0 occurs in the binary word 0,1,0,1,0,0,1. It occurs twice. I ...
32 views

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### Delete elements form a list with elements with strings and numbers

I am trying to create a list list2 removing elements from a list list. The structure of list...
177 views

### Condition on all eigenvalues of a matrix

I am going to help Mathematica to satisfy the condition: If all elements of a matrix's eigenvalues are different from zero, then print "ok" For ...
200 views

### Take elements from a list based on two criteria

I am trying to take elements from a list of tuples using 2 criteria. An example of the list is: list={{-1, -1}, {-1, 1}, {1, 1}, {1, -1}, {1, (1 + I)/Sqrt}} ...
65 views

### How to join two matrix with different dimensions?

I have two matrices with different dimensions I want to join them together in one matrix. for example, I have two lists of diseases associated with their symptoms in both matrix, what I want is to ...
82 views

### Is there an efficient way to fill in the elements of a matrix as m11,m12…etc?

I want to autofill the elements of a matrix (or list) by m11, m12, etc. I am able to autofill using ...
716 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 ...
76 views

### Breaking up a list of lists

I have a list of values stored in SortedLat, where SortedLat is a list of 74 sublists, and each sublist has its first element be a string. As you can see I am trying to create the first column for a ...
78 views

### Visualizing a huge weighted graph

Consider a weighted graph 'net': ...
192 views

### List of lists elementwise greater/smaller than

I have two lists a = {{3,1,2},{5,1,3},{4,1,1}} b = {{4,0,3},{4,2,2},{5,0,2}} And would like to compare each element within ...
210 views

### Find the 3D region containing the origin bounded by given planes

I'm writing a code to generate the Wigner-Seitz cell of the reciprocal lattice for a given set of lattice translation vectors. For example, consider the Body Centered Cubic (BCC) lattice whose basis ...
176 views

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### Merging two rows with rounding their first elemnts

Mathematica shows my data in the below style: ...
1k views

### Why does a table with a defined constant in its index compute 10X slower?

I need to do some iterative summations. Here is a minimum working example: ...
145 views

### Sorting upon the first element of a nested list and show that as numerical values

I wish to sort the below list upon the first elements: ...
71 views

### How to create a list of undefined functions?

I have a undefined function $\phi[i,j]$ where $i=0,1,...,m$ and $i=0,1,...,n$. How can I generate this list: {\$\phi[0,0],\phi[1,0],...,\phi[m,0],\phi[0,1],\phi[1,1],...\phi[m,1],\phi[0,2],...,\phi[m,...
209 views

### Deleting the same lines from a list

Say I have a list of Lines: ...
167 views

### Applying FoldList to its own output

I'm trying to figure out a functional way to essentially apply FoldList (or some related function such as Nest or ...
45 views

### How to calculate a projection of x,y,z data to x any y plane?

I have a List containing x,y,z data, which I can plot nicely in a ListContourPlot: ...