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

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1
vote
1answer
95 views

How to add an extra column to a current matrix (list)? [duplicate]

a = {{-800, 1712}, {-801, 1713}, {-806, 1832}} TableForm[a] b = a[[All, 2]] - Min[a[[All, 2]]] How do I make a new matrix (list) whic looks like this ...
2
votes
1answer
52 views

Simplify on a structured array

Why doesn't Simplify and FullSimplify operate on object generated using SymmetrizedArray? ...
0
votes
0answers
31 views

Copying an Imported List to another File

I have a file which begins with a large list of elements created by joining 12 different data imports, which I would now like to copy to another file so that the file can be sent by itself and not ...
1
vote
3answers
124 views

How to do a Check for every element in the list?

I know how to do a Check for the list in general: ...
1
vote
5answers
135 views

How to split list to strings?

Considering a list: lst = {"1", "2", "3", "4", "5", "6"} How can I have two strings : str1 = "1, 2, 3" str2 = "4, 5, 6" ...
0
votes
1answer
27 views

Add elements of one list to sublists of another list [duplicate]

I have the following list of sublists with different lengths {{1,1,1},{2,2},{3,3,3,3}} and a second list {4,5,6}with the same ...
0
votes
4answers
112 views

Make a program that does union of two lists

I have to make a program that gives as a result the union of two lists using a For loop. I can't figure out how to inspect if the elements of a list are different. ...
5
votes
2answers
169 views

Create a list of rules built from data set fields

I want to convert a dataset to a list of features and a list of target values, for use in Predict and also more generally. I know ...
0
votes
1answer
32 views

Strange behaviour of Append [closed]

I have the following situation and I completely do not understand why the second system can be solved but the first (of the same equations, as it seems) cannot. How is it possible? ...
4
votes
4answers
598 views

Writing a circular matrix

I have two square matrices, $A$ and $B$, of the same size, say, of $m \times m$. What I want is to write a programme/function of three variables, $A$, $B$ and $n$, that outputs the $mn \times mn$ ...
2
votes
4answers
199 views

How to switch from array to string?

Considering we have an array: a = {2/3, 4/5, 9/7, 3/7, 1/7, 1/9}; How can I get this to be: "2/3 4/5 9/7 3/7 1/7 1/9" ...
0
votes
1answer
200 views

mathematica apply list of functions to the same arguments [closed]

EDIT: "Through" is partial solution, because it cannot be used in expressions, where these functions are used without arguments. How can I apply list of functions to the same arguments? e.g. ...
2
votes
1answer
54 views

sparse array with list [closed]

i'm trying to populate a sparse array with lists in certain positions, i tried the following code, ...
4
votes
3answers
118 views

How to map over inner keys of nested Associations?

Considering an association: <|"a" -> <|aa-> "asc", bb-> "asd", cc-> 0, ImageType -> "asd", dd-> "asd"|>|> How can I make the inner ...
1
vote
2answers
50 views

How can I manipulate this list?

I performed a loop with Table where I solve a system of 4 equations that depends on two parameters: eta and p. I create two lists for each parameter as follows: ...
4
votes
4answers
110 views

Creating a new list from other two lists using for loops

I have two lists 'ups' and 'downs' where they are composed of positions of an element in a matrix and their weight. For example, ...
0
votes
2answers
58 views

Writing a function with variable arguments [duplicate]

I want to write a function which takes multiple arguments varying from 1 to n, where each argument is a triplet. sublistProduct[{$a_1,b_1,c_1$},{$a_2,b_2,c_2$},...] = { $\Pi_{i=1}^{i=n}a_i ...
6
votes
6answers
332 views

Total by a criteria

I am developing a weighted KNN algorithm. In a step, I need to do the sum of weights of each class. For example: ...
4
votes
4answers
185 views

How to highlight the elements in a list that match a pattern?

For example, {{1,2,3},{1,2,3,1,2,3,4,5}}with pattern {1,_,3}is transformed to ...
6
votes
3answers
90 views

Comparing elements of a set and deleting elements based on a criterion

I have a function that has two inputs. The first input is a set of 2-element sets, and the second input is a single 2-element set. My function complements each 2-element set with the second ...
16
votes
7answers
733 views

How to use Union on list of lists without sorting them first?

If I do ClearAll[a, d] lsts = {{a, d}, {a, d}}; Union[lsts] I get the expected answer {{a, d}} but if I do ...
0
votes
0answers
39 views

Procedure argument value change [duplicate]

I'm trying to create my own hamiltonian cycle algorithm using Mathematica for school, and I'm stuck on a syntax issue. I get the following error: ...
1
vote
3answers
48 views

Delete permutations of subtables in a table [closed]

I've got a table of tables: $A=\{\{a,b\},\{b,a\},...,\{a,b,c,d,e\},\{e,d,c,a,b\},...\}$. How do I do to remove backward duplicates, or more generally permutations of duplicates in the table? For ...
0
votes
1answer
35 views

Create a Table depending of two variables [closed]

I tried to create a table depending of two variables as: W= Table[{G[[i]], G[[j]]}, {i, 1, 3}, {j, 1, 3}] I wanted it to look like ...
3
votes
4answers
205 views
2
votes
3answers
100 views

DeleteDuplicates in a list of 2-tuples under condition

Having a list of 2-tuples, I would like to delete such 2-tuples that have 0 at second position, but only those, whose first element is not unique in the list. E.g. ...
15
votes
5answers
3k views

Best way to create symmetric matrices

From time to time I need to generate symmetric matrices with relatively expensive cost of element evaluation. Most frequently these are Gram matrices where elements are $L_2$ dot products. Here are ...
22
votes
3answers
1k views

Using pure functions in Table

I need a table with the elements made of pure functions and list elements. This is a simplified example: I need a list as: ...
1
vote
2answers
58 views

How to make function accept list of rules as an argument?

Considering the list of rules: r= {"a" -> "1", "b" -> "2", "c" -> 3, d -> 231, "e" -> 1.25}; I want to have a function ...
79
votes
7answers
21k views

Elegant operations on matrix rows and columns

Question The Mathematica tutorial has a section 'Basic Matrix Operations', describing operations like transpose, inverse and determinant. These operations all work on entire matrices. I am missing a ...
1
vote
3answers
97 views

How to manage list of list of rules?

Considering we have a list: str = "{1 -> {a -> aa, b -> bb}, 2 -> {2a -> \"{b -> bb}\"}}" Bringing this to expression gives: ...
4
votes
1answer
64 views

Automatically assign Variablenames to multiple checkboxes

I want to implement the option to import data from Excel and then the ability to trim this data in order to fit the needs. The import from Excel: (source) ...
6
votes
4answers
285 views
2
votes
5answers
72 views
1
vote
1answer
93 views

Accumulating elements of lists taking the criteria out of another list

In order to find the critical values for the significance of a discrete distribution, for example BinomialDistribution[20,0.6], i need a function which works on the ...
1
vote
0answers
36 views

Combine nested list entries [closed]

I have a list with stock index data (which I load from a database) as follows: ...
0
votes
1answer
115 views

Manipulating list based on Euclidean distance

I have an array of 101 matrices. Each matrix contains information like id, position (x,y,z), time etc about a collection of particles, looks like this ...
5
votes
3answers
213 views

Count elements of a list

Let's create a random list n = 100; data = Table[{RandomReal[{0, 2}], RandomReal[{-1, 1}]}, {i, 0, n}] Now we divide the $(x,y)$ plane into four sectors with the ...
1
vote
1answer
88 views

Summing terms in Table

I have a table that looks like Table[m, {k, 10}, {j, k}, {i, j}] where, m is a square matrix that depends on the indices $i, ...
1
vote
2answers
70 views

Circular Playing up in a Grid

As we know, there is a possibility to emphasize some elements of a Grid by highlighting its cell with ...
23
votes
7answers
659 views

Faster position list construction from a “take instructions” list

Take some list, e.g., {1,2,3,4,5}, and a "take instructions" list, say {1,1,2,1,1}. The latter is read as "take the first ...
13
votes
7answers
755 views

How to sort digits in a string while keeping other characters untouched?

Now there is a string with digits and letters, for instance, "95uge678r3gi89hgfe30kgh063d51". And the expected output is ...
2
votes
3answers
124 views

How to insert a Matrix into a larger matrix

I have a 4x4 matrix v1 v2 v3 v4 myM={{a1,a2,c1,c2}, v1 {a2,a3,c2,c3}, v2 {c1,c2,d1,d2}, v3 {c2,c3,d2,d3}} v4 And I want to ...
8
votes
4answers
731 views

Replacing a for-loop with something functional

I'm a physics grad and have been using Mathematica mostly for data visualization. The evaluation part I normally do with C/Python, but I've been wanting to try out Mathematica for these tasks, too. ...
3
votes
2answers
69 views

SameTest issue?

Folks, I am trying to construct and algorithm which finds all of the remaining groupings (of three items, in this case) from a list of items for which no two items are in groups that have previously ...
8
votes
0answers
97 views

TimeConstrained[Delete[Range[1],1]] causes kernel crash

Run these two samples of code here (AFTER SAVING YOUR CURRENT WORK): Do[ TimeConstrained[ While[True, Delete[{1}, 1]; ];, 0.1];, {100}] ...
3
votes
2answers
84 views
6
votes
6answers
227 views

How to check if two nested lists have the same structure?

How can I check if nested lists like these have the same structure: ...