Questions tagged [list-manipulation]
Questions on the manipulation of List objects in Mathematica, and the functions used for these manipulations.
1
vote
1answer
38 views
How do I divide an integral into parts and sum the total?
I have an exercise looking like this: Analyze the integral $4\int_{0}^{1} \sqrt{1-x^2}\ \tex$ numerically by ng the interval (2,1) into three
equal parts, then summarize the integral parts.
I just ...
6
votes
4answers
118 views
Sort with assumptions
I have a list which looks like this
list = {0, Subscript[x,7], -Subscript[x,3]-Subscript[x,9], -Subscript[x,9]};
and all the $x_i$'s are positive semidefinite (i....
2
votes
3answers
59 views
Divide a list into two lists with equal sums
I have a list with L elements.
I want to find an index within the list, that divides the list to two separate lists so the sum of elements in each of them are equal....
2
votes
2answers
43 views
-1
votes
0answers
36 views
`DistributionFitTest` for 2D data [on hold]
How can I make DistributionFitTest accept 2D data? According to the Documentation - it should be able to accept multivariate data, and the test distribution can be ...
1
vote
1answer
24 views
-1
votes
1answer
57 views
Liquefying of Nitrogen & Oxygen Gaseous to Liquid Phase. Thermodynamics. How to plot solution? Solved
Process of Liquefying of air composed of 79% Nitrogen & 21% Oxygen from Gaseous to Liquid Phases as Follows:
1) When Temperature is higher than T>83 k they both are gas.
2) at T=83 k and less ...
3
votes
2answers
173 views
The multiplication of list of matrices
I need to multiply 3 lists of matrices (b.a.b) as the following code
...
1
vote
1answer
52 views
Attaching independent variable values to data for curve fitting
I have a data set of $10^4$ entries. I want to plot the last $2000$ data with the same argument at $x$ axis and fit a curve. That means the range of $x$ axis will be $8001$ to $10000$ incremented by $...
0
votes
1answer
36 views
AppendTo doesn't update when interacting with PopupMenu
I'm trying to ListPlot a list calculated by the Button called "Plot" with PopupMenu linked ...
5
votes
2answers
110 views
Counting certain elements in lists
I have the following data set:
n1 = 1000;
data1 = {#, {RandomInteger[3, 20]}} & /@ Range[n1];
Dimensions@data1
{1000, 2}
I want to count how often ...
0
votes
1answer
39 views
Select elements from a list depending on condition
Assume I have:
list = {{Mean[{}], 668}, {1, 2}, {Mean[{}], 2}, {7, 8}}
and I want to select only pairs, where the first element is not equal to ...
2
votes
1answer
57 views
Changing the elements of the list based on subscripts
Say I have a list of lists:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],Subscript[a,-3]},
{Subscript[a,1],Subscript[a,-2],Subscript[a,-4]}}
Now, in the ...
3
votes
1answer
113 views
Padding lists for accurate plotting
I have the following data which is in the form of irregular/non rectangular arrays
list1 = {{1}, {2}, {3}, {4}, {5, 6, 7}, {8, 9, 10}, {11}, {12}}
To transpose ...
0
votes
0answers
85 views
3
votes
2answers
53 views
Interleaving position
How could I proceed to interleave the presented values to obtain the same result obtained by this code?
...
1
vote
2answers
38 views
Removing elements from a (nested) list that don't have the same y values as another list
I have two unequal-length lists of ordered pairs and I want to subtract the y-values one (the bigger one) from the other (the smaller one) if they have the same x value. Ideally, I should end up with ...
2
votes
2answers
51 views
Table counting divisors
I have a simple table that I can't quite make work. Columns are as follows
A function returning 1 if x divides ...
0
votes
0answers
50 views
Different Outputs When Calculating Within a Table and Seperately [closed]
I have a matrix which looks like this:
$$\begin{pmatrix} a & e & 0 & 0 \\ 1 & b & 1 & 0 \\ 0 & 1 & c & 1 \\ 0 & 0 & 1 & d \\ \end{pmatrix}$$
where $\{ ...
19
votes
4answers
534 views
Is it possible to avoid unpacking when merging Association?
For example, if we have
assoc =
AssociationThread[{1, 2, 3} -> RandomReal[1., {3, 10}]];
and
...
4
votes
2answers
123 views
Converting from “matrix” data into “coordinate” data
Say I have data which looks like data1 - this is "matrix" like data (is there a better descriptor?). The data looks like a matrix, and at each point in the matrix, ...
2
votes
1answer
54 views
How to force ListPlot to print the new curve while keeping the old one
I would like to create a graph using ListPlot which prints new dataset every time the button is evaluated (based on the value given in ...
5
votes
3answers
220 views
Averaging over columns while ignoring zero entries
I have:
list = {{1, 3, 4, 5, 6, 0, 9}, {4, 0, 3, 5, 0, 2, 0},
{1, 0, 2, 2, 2, 4, 0}}
I want to calculate the average but without considering the 0s.
...
5
votes
7answers
264 views
Generating a list with duplicate entries
How can I get a function that gives the following output?
listX = {a, b, c, d}
numberX = 3
myDuplicatesList[listX, numberX]
{{a,a,a},{b,b,b},{c,c,c},{d,d,d}}
1
vote
1answer
32 views
Table of numbers and their divisors
I want to create a table of random numbers and their divisors. The random numbers are given by
...
3
votes
1answer
33 views
How to check format [closed]
I am having troubles with the following data:
slavelist = ResourceData["New Orleans Slave Sales 1856-1861"]
I want to select all slaves with:
...
4
votes
2answers
60 views
Selecting elements of a list based on frequency
Suppose I have a list as follow:
l = {{"a", "b", "c"}, {"a", "b"}, {"a", "d", "b"}, {"a", "c", "e"}};
Now I am going to flatten it and apply ...
4
votes
2answers
148 views
Commonest[] function doesn't actually show commonest elements
I'm using Commonest function on a list with 500000 words to get the 10 most frequent elements. Then by using WordCloud, I found ...
13
votes
1answer
674 views
Starting index at zero
In order to start an index at zero, I found N. Abbasi is quite convenient. For instance,
(Note that in the original code by Abbasi, one of under scores _ in Notation[] was missing.)
However, with ...
5
votes
7answers
408 views
How to substitute values from a list into a function?
I was hoping to take pairs of numbers from a list and substitute them into a function. So if my list was
list = {{1,2}, {3,4}, {5,6}}
and my function was
<...
1
vote
2answers
127 views
MapThread conflicting with DynamicModule
Cross-posted: https://community.wolfram.com/groups/-/m/t/1625808
Answer posted on Wolfram Community
I'm creating an interactive UI which allows the user to import data from a spreadsheet, perform ...
1
vote
1answer
38 views
7
votes
1answer
351 views
Avoiding unpacking an array when altering its dimension
I am trying to flatten a matrix from 3-dimensional to 2-dimensional one.
The original one has dimension for example {10,120,120}:
...
1
vote
2answers
83 views
reducing matrix size by linear operations on rows and columns
Suppose that I have the following matrix:
matrix = Table[i+j, {i, 5}, {j, 0, 4}];
which generates
I like to write a ...
0
votes
1answer
47 views
Using elements of list to solve a differential equation
I have created a list as shown in picture.
the digits inside f are values of a and q respectively.
I want to solve the Mathieu equation.....
1
vote
1answer
40 views
Inconsistency in SortBy [duplicate]
I have a list of data, I tried to SortBy it in two equivalent way, but the result is different.
The data variable is something ...
0
votes
0answers
35 views
Summing pairs of elements in a list [duplicate]
I have to write a function that returns a list of all different pairs of numbers which add up to 10. For example for {1,9,3,7,8} the function should return ...
5
votes
3answers
261 views
List of numbers giving a particular sum
For the list {1, 9, 3, 7, 8}, I want to find pairs whose sum is $10$. I would like the results shown as ...
1
vote
1answer
62 views
Testing if elements in a list are within a list of ranges
I am trying to check if a list of resistors can be used to achieve a set of equivalent resistances. (Reciprocal of the sum of the reciprocals of the individual resistors is the equivalent resistance) ...
5
votes
2answers
214 views
Manipulating a general length function
As a minimal example, define a function like s[1,2,3]; this is a function of three arguments in this case, but I'd like to apply this general idea to functions like ...
3
votes
2answers
74 views
Convert a list of lists into a list of rules
I have some trouble converting an imported list looking like this:
{{a, b}, {c, d}, {e, f}}
into a list of rules looking like this:
...
2
votes
0answers
87 views
Deciphering the combination of a padlock [closed]
I have a set of numbers from 0 to 9
numbers=Range[0,9,1]
I want to determine the combination of three numbers between 0 and 9. There is a correct combination ...
4
votes
1answer
84 views
Replacement expressions
I have the following expressions:
R[1, 1] R[2, 1] R[3, 1] R[4, 1]
sum[FF[3, ak[1] - ak[2], 1], EE[2, ak[2] - ak[3], 0], EE[2, ak[3] - ak[4], 0]]
By what ...
4
votes
2answers
190 views
Comparing two arrays of unequal length
I have two arrays, say
array1 = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
array2 = {13, 4, 6, 20, 21};
I want to compare these two arrays by cycling ...
0
votes
1answer
45 views
Multiplying corresponding entries in lists [closed]
I have the following lists of probabilities and scores:
...
0
votes
2answers
48 views
Filter lists by discarding sublists that contain integers different from 0 or 1
Imagine I have a list of the type
Lst = {{1,0,1,1},{4,0,1,1}, {1,1,0,0},{2,1,1,1},{0,0,0,1}}
I want to select only those sublists that only contain elements 0 ...
0
votes
0answers
47 views
How to optimize the code [duplicate]
How can I write the following code using lesser number of characters?
Table[Table[{y - x, y}, {y, 8}], {x, 8}]
I tried using ...
0
votes
1answer
46 views
I need an alternative to AppendTo using Reap and Sow
c = Table[RandomVariate[BernoulliDistribution[1/2], 3], 3]
d = Total[c, {2}]
list = {};
For[k = 0, k <= Length[d], k++,
If[d[[k]] == 2, AppendTo[list, c[[k]]]]]
...
3
votes
2answers
105 views
How to remove from the data the rows of with fixed number of elements? [closed]
Consider the data which has the form
data = {{x1,y1,z1},{x2,y2,z2,t2},{x3,y4,z4,t4},{x5,y5,z5},...}
How to remove the rows containing three elements from the ...
6
votes
2answers
147 views
Time-efficient matrix elements grouping and summing
I'm interested in finding the quickest way of grouping the elements of a large matrix in sub-groups of NxM elements and them summing them together.
To be completely clear, I'm actually not interested ...
