Questions tagged [list-manipulation]
Questions on the manipulation of List objects in Mathematica, and the functions used for these manipulations.
6,856
questions
2
votes
3answers
55 views
How to delete consecutive commas in an imported array in Mathematica?
I am importing an excel sheet into Mathematica. The result is a rectangular array. The array contains sequences of commas. Whenever a cell is empty in the Excel sheet consecutive commas appear in the ...
6
votes
2answers
11k views
Principal submatrix and Principal minor of a matrix
A submatrix of a matrix is obtained by deleting any collection of rows and/or columns.
For example, from the following 3-by-4 matrix, we can construct a 2-by-3 submatrix by removing row 3 and column ...
0
votes
3answers
122 views
How to do two different kinds of binning for a given list of elements?
I have a long list consists of float numbers with some of them duplicated as shown below.
I want to divide this list into bins;
with equal bin width so that in each bin there might be one or more ...
10
votes
4answers
484 views
Scan through (partial) tuples
I have a list of list of positive integers $s = \{s_1, s_2, ..., s_k\}$, each list $s_i$ is possibly of different lengths, and I want to find out if there exists a $k$-tuple of the $s_i$ that sums ...
0
votes
1answer
23 views
Part Specification is longer than depth of object & Transposing Errors
In trying to recreate results from another question I had asked (here)
Code is:
...
4
votes
2answers
62 views
From list to unique ID number AND back
If I have a series of list of the form $L_k=\{a_1, a_2,...a_n\}_k$ with $-4<a_i<4$ and $a_i\in\mathbb Z$, then I can make a unique ID number for $L_k$ using ...
1
vote
1answer
27 views
using a list of parameters in NSum
I am trying to make a function that uses NSum, that takes a list of parameters. But NSum doesn't appear to play nicely with lists. A minimum working example is:
...
8
votes
4answers
328 views
Nested Map. Iteration over a list
I am trying to add an element to a nested list. An example of the nested list is given below:
cordxy = {{{1, 2}, {3, 4}, {5, 6}}, {{7, 8}, {9, 10}, {1, 2}}}
I ...
14
votes
4answers
731 views
Generating Linear Extensions of a Partial Order
Given a set $S$ and a partial order $\prec$ over $S$, I'm looking for a way to "efficiently" generate a list of linear extensions of $\prec$. Suppose the partial order is given by a ...
1
vote
2answers
96 views
0
votes
0answers
34 views
Generation of nested list
Does anyone know a better way get the output generated by this code:
Table[Table[{b-a,b},{b,7}]{a,7}]
0
votes
0answers
57 views
Plot a function with specific list of values and use manipulate
I have the following function:
T[r_, theta_] := Cos[theta*\[Pi]/180]*r^2
which I would like to evaluate using predefined values of r from a function which I define ...
0
votes
1answer
42 views
Manipulating lists based on conditionals and 3D plotting the smooth surface that bounds a list of points
First of all I want to create a list of evenly spaceed points in a cubic region in $\mathbb{R}^3$. Then I want to keep the points in this list which satisfy a certain condition, i.e. a function that ...
6
votes
1answer
444 views
DeleteCases messing with my mind
I'm losing my mind. Please tell me my laptop is doing weird things and not me. Or do I need to get committed someplace?
...
0
votes
0answers
31 views
Problem with Table with some conditions [closed]
Please see my code, I have a problem with the Table function because F6, Phi7, and Gamma6 must be added in the calculation but in the result, I want the result ...
0
votes
0answers
25 views
Pure functions with derivatives and list elements [duplicate]
I have a list
list = {x, y, z}
and then the following line
D[#, list[[2]]] &
gives the output
...
0
votes
0answers
34 views
0
votes
1answer
81 views
2
votes
4answers
99 views
What is the easiest and efficient way to get positive or negative combinations of a list?
Consider the following simple case:
list={1,2,2};
Subsets[{Splice[list],Splice[-list]},{1,Length@list}]
This produces the following combinations:
{{1}, {2}, {2}, {-...
0
votes
1answer
44 views
select partially matching filenames
I have two lists of files with slightly different naming conventions
...
0
votes
0answers
33 views
2
votes
0answers
82 views
Repeated calling of a ParametricNDSolve result in a faster way?
I recently learned of ParametricNDSolve and found that I need to compute it once and then call its result sol at different ...
2
votes
1answer
68 views
Formatting Imported Complex Arrays from Python (csv. files)
Just a short question, I am trying to import a complex array (matrix) from Python to Mathematica by first writing to a csv. file. When I Import the csv. array to Mathematica it is in a form (matrix ...
0
votes
1answer
55 views
SphericalPlot3D for a list
This question was asked before (here), but I couldn't get the answers to work.
I have a list of values
...
0
votes
2answers
439 views
Mathematica: how to make Z transformation of data from CSV File
I have a discrete Signal in my CSV File and I want to transform it in Z. I import the data with
Data=Import["T:/data.csv","CSV"]
and I try to transform it
<...
9
votes
6answers
436 views
How to judge whether two groups of sequences are equal in cycles?
There's a set of arrays that I want to remove repeated elements that are equal after rotation:
...
3
votes
2answers
78 views
Creating a list polygon's vertices from two lists of points
I would like to construct a list of polygons by using two different lists of points:
...
1
vote
1answer
40 views
table indices matching?
is there a way I can do something like, if
h = Table[i, {i, 0, 5, 1}]
so, I can access the 4th element of the h[[4]], so, what about going other way around that 3 ...
1
vote
0answers
41 views
Tables equates?
Is there any way if I can equate these two table,
h = Table[i, {i, 0, 5, 1}]
p = Table[j, {j, 0, 255, 51}]
now how can I equate these two tables, let's say 0 of h ...
0
votes
1answer
73 views
Using MapThread and ReplaceAll together
I am trying to carry out some operations on the elements of dataset2, which is an 11 x 14 x 6 dimensional array:
I have a function, ...
6
votes
1answer
122 views
Performance of select from a 3d list - Mathematica slower than Python
I am creating a random 3d data set in Matematica 12.1. Then I am selecting all points that are in a certain range of one axis.
The same I am doing in Python (same computer, Python 3.8.5, numpy 1.19.2)
...
3
votes
1answer
89 views
How to generate isotropic tensors?
Consider a real tensor $\bf{T}$ upon $\mathop\otimes\limits_{n}(\mathbb{R}^3)$, with a definite order $n$, it could be isotropic, i.e., be invariant under the action of all elements in $SO(3)$(not $O(...
4
votes
3answers
97 views
Union of list with logical rules for combination
I have an list that I would like to reduce according to rules for combination. Examples of the input list (this will be a list of pairs and may be several hundred elements long) and the output I'm ...
3
votes
2answers
110 views
How to split a list based on pattern
I am trying to split a list based on pattern of some elements of the list.
list = {a^(-1-x1),b^(-x2), (a+b)^(-x3), (1-a)^(-1+x4),(1-b)^(-1), (1+a b)}
I want to ...
1
vote
0answers
66 views
How can I make 3 separate tables of parameters instead of only one table like this?
In the code below, how can I make 3 separate parameter tables for tup1, tup2, tup3 and plot ...
2
votes
2answers
127 views
Plot a list of functions with a corresponding list of ranges
I have 3 functions below and I want to plot them on the same graph with different range as follows.
Plot f1 with x is in ...
2
votes
1answer
76 views
Multiply lists: element-wise but matrix-like in the last 2 levels
How can I do the following computation more efficiently? We have nested lists and want to multiply element-wise, where the 'element' is the deepest 2 levels treated like normal matrix multiplication. ...
0
votes
1answer
65 views
How to create a set (of matrices) which will be used as an finite group to minimize a function?
I'm new here so I'm a little lost.
I need to minimize a function considering that the minimizing parameter belongs to a preestablished set. It all involves matrices.It's something like this:
Where ...
6
votes
2answers
135 views
How to extract a column (or a row) of a matrix as another column vector/ column matrix (or a row vector), not as a list?
Suppose I have a matrix 'mat' as
mat = Table[Subscript[m, i, j], {i, 5}, {j, 5}];
mat // MatrixForm
I want to extract the first column (or any row) as
...
5
votes
2answers
129 views
Unexpected timing result of Total and Part performance of packed array
Define
a = RandomReal[1., {2, 100, 100, 100}];
then
Total[a, Infinity]; // RepeatedTiming
{0.00183727, Null}
and
...
0
votes
1answer
71 views
Unable to operate on the table imported from .mx file
I saved a table by exporting it to .mx file. Now, when I import it back, it gives me the desired output.
So, to work with elements of the table, I first define the imported table as (...
4
votes
1answer
36 views
Select from list using a TogglerBar to specify one or several criteria
Simple version of my problem. Create a list of 50 integers. Create a TogglerBar to select one or more members of the list. Use Select to select sublists from the larger list. I can't figure out how to ...
1
vote
1answer
131 views
How to speed up by Compile?
I need to NDSolve a system many times by scanning some of its parameters and do some matrix calculation with the (discretized) solutions. The example is the ...
1
vote
1answer
49 views
1
vote
1answer
383 views
Extracting unique values from array
I performed MorphologicalComponents on an image, and from there used SelectComponents to filter out my desired components. Is there a way to extract out the unique values from the entire array? i.e. ...
3
votes
1answer
104 views
Mathematica shorthand for mapping function over two lists simultaneously [closed]
I am still relatively new to Mathematica, so please bear with my question. I have the following statement that works perfectly well:
...
32
votes
6answers
2k views
Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$.
Looks like a question for pupils, right?
In fact, if the available math symbols are limited to addition ($+$), ...
0
votes
1answer
88 views
Moving average of events per minute
Suppose I have a list of times corresponding to event onset over the course of about an hour (in my case, skin conductance responses from electrodermal activity measurements). The amplitude of the ...
1
vote
2answers
607 views
3
votes
2answers
216 views
Elegant way to rearrange year/date table into time series/values
I often have data in the form of
YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1950 -1.022 -1.146 -1.289 -1.058 -1.419 -1.36 -1.334 -1.05 -0.578 -0.395 -1.151 -1.248
1951 ...
