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Questions tagged [list-manipulation]

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

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Automate generation of new list

Suppose there is a list of lists as follows: BigList={{1,2,3},{4,5,4},{7,7,9},{10,11}} and it is required to apply a given command separately on each sublist ...
vyali's user avatar
  • 101
0 votes
0 answers
66 views

Fastest way of removing outliers from a data set which depends on a variable

Suppose we have the following code: ...
Arbuja's user avatar
  • 87
3 votes
1 answer
115 views

Numerical precision of keys in Merge function

I'm trying to merge list member with the same numerical key values: a = {53.8 -> x, Floor[53.81`, 0.2] -> y}; Merge[a, Total] then I get: ...
Ming's user avatar
  • 305
3 votes
1 answer
109 views

How to delete members of a list by rule [duplicate]

I have a list: lis = {"a",1,""} and would like to delete from the list all elements that consist of "" to give: ...
Suite401's user avatar
  • 5,005
-2 votes
3 answers
79 views

How to rearrange the list by the number of elements? [closed]

...
csn899's user avatar
  • 4,842
1 vote
1 answer
56 views

Applying a condition to a column in a table using If

Let's assume we have the code below (The below code is derived from answer @DanielHuber link and answer @Domen link) ...
Emad kareem's user avatar
  • 1,014
3 votes
6 answers
280 views

`Drop` for list of elements of different dimensions

MWE is the following list {{{1,2,3},4},{{a,b,c},d}} I want to Drop the 3 and c here. (In reality, it is a very long list of ...
Confuse-ray30's user avatar
4 votes
4 answers
457 views

How to raise a vector to powers contained in a vector, change the list into a product, and do this for all the lines of a matrix, efficiently?

I want to raise the first vector var to the powers in a second vector, and then multiply the list, when the second vector runs over all lines of a matrix ...
florin's user avatar
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2 votes
5 answers
279 views

How to find intersecting linear equations between two lists?

I have two lists of linear equations: list1 = {x - y == 0, x + 2y == 0, 3x - y == 0} list2 = {-x + y == 0, -x - 2y == 0, 3x - y == 0, 3x - 2y == 0} I want to ...
internet's user avatar
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0 answers
44 views

How to solve numerically a fourth order BVP having a Boundary condition at Limit Approaches to 0

I have the following fourth order BVP (pde): $\frac{1}{4}f_{yyt}+H^{4}(ff_{yyy}-f_{y}f_{yy})=\frac{1}{H^{2}R}(yf_{yyy}+2f_{yy})$ with boundary conditions: $f(0,t)=0$, $f(1,t)=0$, $f_{y}(1,t)=-\frac{\...
Junaid Ahmad's user avatar
-1 votes
1 answer
67 views

Match list to a pattern [duplicate]

I want to match a list to a pattern, but MatchQ is not doing the job as needed. For example, I need: ...
Morgan's user avatar
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4 votes
3 answers
340 views

Fourth order BVP partial differential equation

I am trying to solve fourth order partial differential equation describing a fluid problem, by using Mathematica. The PDE is provided here as: $(1/4)f_{yyt} + H^4(ff_{yyy} - f_y f_{yy})=1/{H^2R(yf_{...
Muhammad Zeeshan khan's user avatar
1 vote
1 answer
85 views

How to generate all possible combinations subject to symmetry conditions

I have a list of 6 (possibly repeated) integers: ints = {a,b,c,d,e,f}; and also a set of symmetry conditions: You can switch the signs of elements 1 and 4 at the ...
Morgan's user avatar
  • 575
3 votes
3 answers
201 views

Function to find the most common numeric ordered pairings (value, count)

Let us say that I have a list of numeric ordered pairs where the first number represents a value to be counted and the second number represents the count of that value. The following is one way to ...
anonmous's user avatar
  • 121
0 votes
1 answer
38 views

Add a new column based on the complement of column data in a table

I have this code to replace the data of each row in a specific function and display a new column showing the values ​​of the function ...
Emad kareem's user avatar
  • 1,014
1 vote
1 answer
59 views

Finding the position of a list element using functions like Max on lists that might contain 'Indeterminate' values

I am working with lists of the following form: ...
anonmous's user avatar
  • 121
2 votes
2 answers
75 views

Best way to extend the size and add terms to a SparseArray without expanding

Let's say I have a "small" SparseArray of any size, in the example $2\times2$ ...
rhermans's user avatar
  • 37k
0 votes
0 answers
49 views

Operations on Sub Lists

Let us assume that I have the following list of lists: foo = {{2, 1}, {3, 1}, {4, 1}, {2, 2}, {3, 1}, {2, 1}}; and that I want to multiply the elements of each sub ...
anonmous's user avatar
  • 121
2 votes
2 answers
164 views

Union of lists with original order

I would like to combine a few lists such that the resulting list follows the order of the original lists, which will have disjoint elements, but their order is compatible. ...
Albercoc's user avatar
  • 1,102
1 vote
1 answer
80 views

How to check equivalence when variables in equations are replaced by their negatives?

In a previous post about checking whether two systems of equations are equivalent, the suggestion was to use the Reduced Row Echelon Form, which was great. However, I now want to consider an ...
internet's user avatar
  • 723
1 vote
2 answers
81 views

Reshaping a list as another nested list

I have the following list ( p to be some even number ) ...
Erosannin's user avatar
  • 307
3 votes
1 answer
86 views

Find positions of unique elements in a nested list

I have a nested list with depth 6. The items in the list are mathematical expressions. I want to find the positions of the unique items in the nested list. I have found the following, which works for ...
Morgan's user avatar
  • 575
4 votes
3 answers
209 views

How to make a list plot from a "vector array"?

I have an (excel) table where my first column have decimals from -3 to 3, and the other columns have associated values, in such a way that i have a "vector array" similar to this: ...
McNess's user avatar
  • 43
0 votes
1 answer
31 views

Solving list manipulation exercise involving longest sequence of identical digits in a list using functional programming idiom

I have been trying to improve my list manipulation skills by doing some of the exercises in Wolfram's Intro book. I am struggling to solve this question using only functional programming constructs. ...
Jim Marks's user avatar
  • 189
1 vote
3 answers
158 views

How can I get a list of tuples which sum to zero for three lists of labelled vectors

...
gunes's user avatar
  • 381
1 vote
1 answer
47 views

Applying the binomial distribution to matrix data

The probability that a random variable $X$ with binomial distribution $B(n,p)$ is equal to the value $k$, where $k = 0, 1,\dots,n$. If we have the $(n\times m)$matrix and $N_j$, $$f(x)= 1/2 \binom{3}{...
Math-babylon's user avatar
4 votes
4 answers
279 views

How to combine some ordered pairs

I have a list of ordered pairs: {{1, 1}, {1, 2}, {2, 4}, {1, 2}, {1, 2}, {2, 4}, {2, 4}, {2, 4}, {4, 4}} If two pairs {x_1, y_1}...
Geoffrey Critzer's user avatar
1 vote
0 answers
48 views

Formatting control points for BSplineFunction

I am trying to create an approximation to a level surface $F(u,v,w) = 0$ using BSplineFunction and control points sampled from the ContourPlot. I want to use these points to make a 2-variable ...
user192413's user avatar
3 votes
2 answers
96 views

Flatten bottom $n$ levels [closed]

The documentation for Flatten states: Flatten[list,n] – flatten out the top $n$ levels in list Does a function exist to ...
Kay's user avatar
  • 1,077
-1 votes
2 answers
109 views

Combinations of two table

I would like to find all the possible combinations between TSet1 and TSet2 to create a table of 18 rows. ...
Emad kareem's user avatar
  • 1,014
1 vote
0 answers
73 views

How can I make a list containing 5 rows and 10 columns from a list? [closed]

I have a list list = RandomInteger[{10, 100}, 100] I want to make a list containing 5 rows and 10 columns. I tried ...
Thuy Nguyen's user avatar
  • 1,265
3 votes
3 answers
240 views

Inserting a 0 in Specific Symbols

I have a very large network with 1000's of edges. Below is a small sample. The N is my label for Node and the number that follows is a unique identifier. I want to make all the edges on either side of ...
user42700's user avatar
  • 1,817
1 vote
1 answer
56 views

How can I compute the cross product of some sets of ordered pairs?

I have a list of sets of ordered pairs: {{{1, 1}, {1, 2}, {2, 4}, {4, 8}}, {{1, 1}, {1, 2}}, {{1, 1}, {1, 2}}} There are 4 ordered pairs in the first set, 2 ...
Geoffrey Critzer's user avatar
-2 votes
1 answer
79 views

How can you transform the format of letters in a list?

Q1:How to convert list1 into list2 list1={A, B, C, D, E, F} ...
csn899's user avatar
  • 4,842
2 votes
2 answers
97 views

Condition on the data of table

If you have a table and want to separate some data into columns according to certain conditions: Let's assume we have the following table: ...
Emad kareem's user avatar
  • 1,014
5 votes
3 answers
427 views

How can I count frequency of a list faster?

I have a list list = RandomInteger[{120, 180}, {20}] I want to count from the list elements $a$ satisfying conditions: $120\leqslant a <130$, $130\leqslant a &...
minhthien_2016's user avatar
3 votes
2 answers
66 views

Using PutAppend to create data file for 2D plot

I need to append 2 real numbers x,y (a point coordinates) to the bottom of a file, so that these numbers form 2 columns, the x column and the y column. I need to plot the points later. Doing this: <...
Mike's user avatar
  • 131
0 votes
1 answer
64 views

How to convert a $2 \times 2$ matrix with entries of $4 \times 4$ matrices into a regular $8 \times 8 $ matrix

I have tried to create the following matrix $$\begin{bmatrix} 0_{4} & \mathbb{I}_{4} \\ \mathbb{I}_{4} & 0_{4} \end{bmatrix}.$$ I have used the following code ...
am567's user avatar
  • 673
3 votes
4 answers
145 views

List editing problem

I have an ill-formed list: ...
Suite401's user avatar
  • 5,005
2 votes
1 answer
119 views

Central element of matrix

Let we have $(2\cdot r+1) \times (2\cdot r+1)$ matrix mat. Is there a better way to extract it's central element, rather than ...
lesobrod's user avatar
  • 1,904
6 votes
3 answers
190 views

Generate a table of elements whose number is equal to prime numbers

I have a list of words (strings) same as ...
monfneg's user avatar
  • 659
1 vote
2 answers
71 views

Randomly replace some letters in words with hyphen

I have a list containing some related words ...
monfneg's user avatar
  • 659
1 vote
1 answer
82 views

Find the feasible solutions of a minimal path set of vectors

Finding the feasible solutions for vectors representing minimum paths based on the mathematical basis: First example I need to create the constraints according to equations (1) and (2) above: ...
Emad kareem's user avatar
  • 1,014
1 vote
1 answer
65 views

Max and Transpose in the Probability of a Union

If I have the code that gives the probability of the sum in general ...
Emad kareem's user avatar
  • 1,014
1 vote
2 answers
131 views

Probability of a union with probability function of vector

I want to calculate the probability of a discrete random variable. ...
Emad kareem's user avatar
  • 1,014
0 votes
1 answer
55 views

Apply an equation based on two sets with different indexes

Apply an equation based on two sets with different indexes Simple example If I have the following elements in the form of two sets with different indexes: $m=\{m_1,m_2,m_3,m_4,m_5\}=\{1,2,2,2,1\}$ $p=\...
Emad kareem's user avatar
  • 1,014
7 votes
2 answers
286 views

How can I sort all levels except the innermost level?

How can I sort all levels except the innermost level? The number of levels is unknown. For example: list = {{{d, c}, {b, a}}, {{4, 3}, {2, 1}}} If we needed to ...
internet's user avatar
  • 723
0 votes
2 answers
78 views

Other methods extract the x-coordinates and y-coordinates from a list of multiple coordinate values and list them separately in two individual lists? [closed]

x={0.04,0.06,0.04,0.08,0.08,0.05,0.05,0.07,0.07,0.06} y={0.25,0.4,0.22,0.54,0.51,0.34,0.36,0.46,0.42,0.4} The two lists above represent sets of x-coordinates and y-...
csn899's user avatar
  • 4,842
2 votes
3 answers
304 views

Filling the areas enclosed by two curves and calculate them

I know that there are plenty of posts on this, but I just cannot find the right one that solves my issue. The issue is that I have two datasets that I plot them using ...
KratosMath's user avatar
  • 1,309
5 votes
3 answers
438 views

How to optimize performance with DeleteDuplicates?

Does anyone know how to improve this for speed performance? The code works fine, but DeleteDuplicates makes it really slow for large lists. ...
internet's user avatar
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