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

learn more… | top users | synonyms (5)

2
votes
3answers
113 views

Comparing two lists lexically

I have two lists of integers a and b of equal length, and I would like to define a>b as ...
1
vote
2answers
327 views

What quantity is this “length” called?

tmp = {x, y, z}^{1, 2, 3} Times @@ tmp Length[%] This gives a length of 3. But I was expecting 1. What is exactly this "length" of x*y^2*z^3 called? I would ...
1
vote
1answer
180 views

Mathematica List Selection

I have a list which contains these elements : ...
1
vote
1answer
178 views

Finding the index of (x,y) pairs in a list

I have a large list of $(x,y)$ pairs, and I want to find the index of a particular pair in order to extract some data from another array. By way of an example, ...
0
votes
1answer
112 views

Why `Delete` does not work?

I'm trying random thing in Mathematica just for learning and I can't solve this problem. I want to use the Detele function to delete some elements in a list but ...
2
votes
1answer
94 views

Displaying a list in form of an upside down pyramid graphic

I was wondering how to display a list like this: list={{0,1,1,0},{1,0,1},{1,1},{0}} in form of an upside down pyramid, that is the first element of the list is ...
5
votes
3answers
800 views

How to build this grid with less code?

I have the diagonal and both upper and lower triangulars of a grid. ...
4
votes
2answers
85 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
175 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 ...
6
votes
6answers
362 views
0
votes
3answers
79 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}}
3
votes
3answers
204 views

Pare down list recursively

What is the best way to pare down a list whereby the $n$th number is removed from the list recursively? This ...
1
vote
6answers
115 views
1
vote
1answer
42 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 ...
1
vote
2answers
128 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
175 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 ...
3
votes
3answers
204 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 ...
2
votes
0answers
70 views
8
votes
1answer
247 views

Transformation rule on a list of non-negative integers

I am trying to create a transformation rule that takes a list of non-negative integer values of any length, finds a non-zero entry in the list, adds 1 to all preceding numbers, subtracts 1 from the ...
4
votes
3answers
284 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 ...
0
votes
2answers
99 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 ...
1
vote
1answer
205 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 ...
5
votes
3answers
167 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 ...
1
vote
2answers
53 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: ...
3
votes
3answers
83 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 ...
9
votes
3answers
250 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 ...
1
vote
1answer
162 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? ...
13
votes
1answer
456 views

How can I collect data for visualization of quick sort?

I know how to implement quick sort in Mathematica. But I don't know how to get the temp data for visualization, because I used recursion. I want the effect similar to this: ...
15
votes
4answers
834 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 ...
8
votes
3answers
315 views

How to remove a line of a matrix if not all elements are numeric?

I have a matrix a n columns and m lines. I'd like to efficiently remove the lines that are not entirely composed of numeric ...
6
votes
0answers
461 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
627 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 ...
10
votes
4answers
502 views

Building a tree

Given a list of word characters, such as this one, I'd like to build a tree, similar to this makeTree function, but with the tree in a different format. So, for an input such as ...
3
votes
1answer
152 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 ...
4
votes
7answers
180 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: ...
3
votes
4answers
2k views

ListPlot multiple datasets over same x-values

Is there a better way to enter my data into a list plot? ...
12
votes
3answers
262 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: ...
3
votes
3answers
375 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} ...
5
votes
2answers
412 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 ...
1
vote
1answer
123 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 ...
0
votes
3answers
114 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}) ...
-1
votes
4answers
149 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
4answers
102 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 ...
4
votes
7answers
128 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: ...
2
votes
4answers
420 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 ...
1
vote
1answer
240 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) ...
0
votes
1answer
35 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 ...
0
votes
1answer
88 views

Finding duplicates in a list [duplicate]

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 ...
13
votes
3answers
1k views

What is the most efficient way to map a linked list?

In order to work with lists effectively using common recursive patterns from functional programming, it's often most convenient to worked with the "linked list" representation, that looks like this: ...