Tagged Questions

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

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0
votes
0answers
45 views

Mathematica List Selection

I have a list which contains these elements : ...
1
vote
2answers
102 views

Merging two lists with possible different keys

This is very similar to my earlier question One to Many Lists Merge but somehow different. I have two lists, first column in each list represents its key. I want to merge these two lists. The only ...
3
votes
2answers
51 views

How to keep first observation and delete other observations of each group in unbalanced Panel data

I have a huge panel data. I want to create a new data keeping only first observation of each group. How can I achieve it? For illustrative purpose; ...
2
votes
3answers
153 views

Splitting a list of lists (part2)

This is a follow up from Splitting a list of lists . What would be a nice way to split the list l1 = {1,2,{a,b,c},3,{d,e}} into ...
0
votes
1answer
56 views

Duplicate values n-times [on hold]

I already asked how I can take the list {1,2,3} and get {1,1,1,2,2,2,3,3,3} out of it, adding degeneracy to the problem. So far ...
0
votes
3answers
66 views

Splitting a list of lists

What would be a nice way to split the list list = {1,2,3,{a,b,c},4} into {{1,2,3,a,4},{1,2,3,b,4},{1,2,3,c,4}}
0
votes
0answers
37 views
1
vote
1answer
29 views

Generate Degeneracies in List [duplicate]

I have a list with n entries and I would like to duplicate this list p times. In my case because of the Degeneracy of my Eigenvalues. For example I have {3,2,1} and it is five-fold-degenerate so that ...
8
votes
5answers
385 views

How to subtract one list from another, treating each elements as distinct?

Suppose that I have a = {"A", "A", "A", "B", "B", "C"} b = {"A", "B"} How can I subtract b from ...
1
vote
7answers
93 views

Make a new list by filtering unwanted rows

I have a list like this. ...
1
vote
2answers
60 views

How do you apply an algorithm individually to an array with many graphs

I have and array with many graphs to which I want to apply an algorithm (below) to each graph in an array that contains all my graphs. ...
2
votes
2answers
100 views

Understanding `NestList` with multiple functions

General question For a function f[n, a], where a is a list and n is a whole number, what is ...
2
votes
3answers
137 views

Deleting missing data with CountryData

I need to delete all of the missing entries after executing this line: ...
3
votes
3answers
154 views

How to detect outlier in data of an unknown function $f(x)$

Suppose I have an unknown function $f(x)$ that is monotonic, convex and nonlinear by definition. I somehow evaluated it at 1000 nonuniform $x$ points. By ploting these data, I found a very obvious ...
5
votes
3answers
124 views

Missing control for depth of Inner

Working on a mechanics problem, I stumbled on something peculiar: Since Inner is a generalisation of Dot, it changes its ...
0
votes
1answer
70 views

Recursive functions taking list arguments

I wish to create a function that takes lists (e.g. {plus,plus,minus,0,minus,plus}) and uses the input list to calculate a corresponding value using a set of ...
2
votes
0answers
53 views

Choosing a List as VertexWeight for a TreeGraph

I would like to map every vertex of my TreeGraph to an List. ...
1
vote
2answers
44 views

How to add a part of a list to a function?

I want to be able to add a specific portion of a list to a part of a function but this fucntion intakes 6 variables where as the list is of example: ...
0
votes
2answers
82 views

Finding an idiomatic way to express a system of linear equations

I have an $n$ x $n$ matrix $T$, where $t_{ij}$ is the element at the $i\,$th row and $j\,$th column, and unknowns $x_i$, $1\leq i \leq n$, where $$x_{n} = 1$$ $$x_{n-1} = 0$$ $$x_i = \sum_{1\leq j ...
4
votes
3answers
153 views

Polynomial with alternating sign coefficients from the odd degree terms of a Truncated Power Series

I'm trying to make a function that will take any truncated power series I give it, strip away all the even degree terms, then change the sign of the coefficients of every other term. So that we have a ...
3
votes
3answers
76 views

Generating increasingly longer lists from a single list

I start with an array such as {{1,1},{0,1},{-1,1}}. (1) I want to create an array from this which replaces each array inside the array with 3 new arrays, one ...
1
vote
1answer
69 views

Transform a rule to a list of rules

How can this rule a -> {1, 2, 3} be transformed into this {a -> 1, a -> 2, a -> 3} by way of a function? ...
8
votes
3answers
140 views

Complicated list slicing

Say I have a list with the structure list = {{1, {x1, y1, z1}}, {2, {x2, y2, z2}}, {3, {x3, y3, z3}}, ...} I would like to slice it such that I end up with ...
0
votes
0answers
35 views

Using List/Histogram Data As A Weighted Function?

I have a list of data points that I would like to use as a weighted fucntion. The data represents the number of particles within a bin of a particle distribution. Ultimately I would like to multiply ...
5
votes
1answer
63 views

Enumerating tuples from a larger space such that all pairs of values are present at least once

I am trying to write a function that will accept a list of N lists and returns a list of N-tuples that represent all pairs of values from the original N lists at least once. To illustrate with an ...
1
vote
1answer
32 views

Easy way to perform multiplication of two 2x2 matrices, that contain list elements?

I have two 2x2 matrices, which elements are lists (so overall structure can be complicated). I need to perform matrix multiplication of these 2x2 matrices as if the elements didn't have its inner ...
5
votes
0answers
117 views

How to download and combine S&P 500 stock prices

I want to download historical S&P 500 stock prices and combined them into one big file, having only one column of date referencing all stocks. Here is what I have do so far. ...
6
votes
5answers
539 views

What is the best way to draw a shaded table?

I'm trying to format a raster-style table with row and column headings and in which each cell is shaded according to the value in the cell, and the value of the cell is displayed in as text in a ...
0
votes
0answers
10 views

Formula to divide (group) numbers into N proportionally groups [migrated]

Lets take ideal theoretical case as example: we have 20 numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 we should split these numbers into 5 groups: lowest, low, ...
-2
votes
0answers
19 views

Defining an ORIGINAL derivative function? [duplicate]

NOTE: I do not want to use the Derivative or D functions. – I want to define an original function. I began with this definition of the derivative , which resulted in: Limit[ #, h -> 0] & /@ { ...
3
votes
7answers
135 views

Get the position of the right interval

I have a list of intervals: Intervals = {{0, 1}, {1, 2}, {2, 3}, {3, 4}, {4, 5}, {5, 6}} and a list of measurements: ...
15
votes
4answers
412 views

Exclude data from a list

Let's create some random sample data data = Table[{RandomReal[{-10, 10}], RandomReal[{-10, 10}]}, {i, 1, 300}]; Then we plot them using ...
10
votes
3answers
235 views

Using 0 to create new columns in a list with Part

I just discovered a nice way to create intermediary columns in a list, and I would like to know if I can have some problem with it. It Works like this: Imagine I have this list, 5x3: ...
4
votes
2answers
123 views

How to exclude some indices in defining Table?

Suppose I define a table using Table[n, {n, -n0, n0}] (where n0 is some positive integer) but I want n not to take the value ...
2
votes
3answers
89 views

Compare 2 lists

I want to compare 2 lists. One is very large and I need to compare many times. Lets say Length[list1] I need to know how many times list1 occures in list2. Eg. list1={1, 0}, list2={1, 0, 1, 0, 1, 1} ...
1
vote
1answer
44 views

Lists of integers coprime to another list

I have two lists of integers. The first, p, is a list of primes (for example, {2,3,5,7}). The second is a list ...
-1
votes
4answers
61 views

Eliminate symbols from Lists

I'm working with a list of roots of a 3rd order polynomial family, so i get a list this way: ...
0
votes
3answers
103 views

Manipulate list in function

I have some problems with lists and functions. Basically I just want to cut all entries from the right side, which contain 2. ({2,1,2} should become {2,1}) ...
5
votes
5answers
416 views

Efficient Indexed Sort

Suppose I have a preference for animals given by: orderOfAnimals = {"dogs", "cats", "fish", "elephants", "giraffe", "hamsters", "poodles"}; I'm given many data ...
0
votes
4answers
86 views

How to express “if any component in a vector satisfies that …” in Mathematica

For example, l is a list of vectors. I need to delete from l all the vectors with any component larger than 1. How should I do ...
0
votes
1answer
18 views

MapThread with incompatible length (How to Map twice in the same line)

l and b are two lists of vectors with different length. I need the list of vectors that is constructed by adding each member of ...
1
vote
4answers
75 views

Removing all values from a list that satisfy a given condition

Suppose I have a list, list = Table[{n}, {n, 1, 5}] (* list = {{1},{2},{3},{4},{5}} *) and I want to remove all values from this list that are greater than 3, so ...
0
votes
1answer
32 views

Error: in the part assignment is not a symbol [duplicate]

I am trying to set part of a Doubly-indexed list aInitialPopulation to cNumHeg. Specifically I am trying to set the 3rd part of the list aInitialPopulatiom[[cNodeNumber]] to cNumHeg. My (attempted) ...
4
votes
7answers
115 views

Distributing identifiers

I have a list that looks like this: {{"a",},{2010,0},{2011,10},{2012,27},{"b",},{2011,11},{2012,66},{"c",},{2010,19},{2011,20},{2012,}} I want to turn it into: ...
0
votes
1answer
60 views

Finding duplicates in a list

I have a list of integer, and I want to know if the list contains any duplicates. My code is working, but I feel there is a more straightforward way of doing this ...
2
votes
1answer
112 views

Excluding cases from Map

I'm doing operations of the form: PowerMod[#, -1, 126]+# & /@ Range[1, 125] When a number is not invertible, I don't want it to be included in the result ...
4
votes
2answers
59 views

How to sum values in the list that belongs to same week

I need to sum values that belongs to same week. For example, I have the list x with one column and n rows. Format: ...
3
votes
3answers
101 views

Finding the first position in a list that is over a certain value

Let's say I have the following list: L = {2,4,6,8,10} How can I get Mathematica to find the index position of the first value in the list that is over 4 (6 in ...
2
votes
3answers
61 views

How to manipulate one column of a table using the value in another column

Let's imagine I have the following table structure data = {{a, b}, {c, d}, {e, f}}; and I want to transform it into the following table ...