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

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1
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2answers
372 views

Specifying parts from lists for plotting using Show

I have the following data: ...
0
votes
1answer
1k views

Table - find index of the maximum element [duplicate]

Let's suppose that I have table t = {1.23, 3.4, 10, 34, 1.78, 0.98, 12.56}. To take the biggest element I can use Max[t] ...
10
votes
2answers
314 views

Conditional Gathering of lists

Just need a little help with the GatherBy / SplitBy function(s). I have a list of random numbers here: ...
9
votes
4answers
284 views

MapThread with non-rectangular lists

MapThread works fine and dandy with rectangular list structures: MapThread[f, {{{a, b}, {c, d}}, {{1, 2}, {3, 4}}}, 2] ...
7
votes
1answer
287 views
7
votes
4answers
218 views

Button's command is not evaluated in iteration

I wish I didn't feel like a newbie after several months, but... If I enter the following: Table[ Button[ "Number: " <> ToString @ i, Print @ i], {i, 1, 5}] ...
6
votes
8answers
231 views

Merging lists and adding common elements [duplicate]

I have two 2D arrays where some of the x-values are identical, L={{1,1},{2,2},{3,3}}; J={{0,1},{2,2},{4,4}}; I want to add these lists in the following way ...
6
votes
6answers
372 views

How can I merge two lists in a special way?

It's been over a year since I've used Mathematica, and I'm having a total brain fart on a home project. I'd like to take an existing list of lists, say, ...
5
votes
2answers
215 views

Better method for creating a tuple out of two lists

I just combined two lists using this method ...
5
votes
2answers
421 views

Add elements in a sublist

I have created a subset of arrays: ...
4
votes
2answers
183 views

Correlation with missing data

I have two lists, age and score, that I want to find correlation on for 50 people. For some people, the score is blank. Example data: ...
4
votes
5answers
825 views

Removing zero values from ordered pairs

I have some processed data, which are basically a collection of ordered pairs in the form: {{x1, y1}, {x2, y2}, ..., {xn, yn}} Ordered pairs which have either a ...
4
votes
1answer
299 views

Path queries for tree-structured data

Can anyone suggest documentation or tutorials for developing path queries and indices for (XML-like) tree-structured data? Suppose data is organized hierarchically in key->value pairs, eg: ...
3
votes
1answer
149 views

Select row from a table by column value [duplicate]

I have the following: animals = {{dog, black, 200}, {cat, white, 100}, {moose, brown, 500}, {zebra,black,100}} If this came from a SQL table called animals, ...
3
votes
3answers
160 views

Picking certain pairs according to a condition [duplicate]

I'm a Mathematica beginner and can't find out a solution to my problem. I have a list of pairs of numbers, for example something like this, but much longer: list={{2., 3.}, {3., 2.}, {5., 4.}, {4., ...
3
votes
5answers
388 views

How to combine some elements of a list?

In order to simplify my expression, I face a list manipulation problem. For example, given the input list ...
3
votes
2answers
418 views

hexList[[1]] returns a list of decimal numbers

Sorry for not being clear about this question earlier. I appreciate the answers I got, but the edits I made should make the question more understandable. I have been working with hex in ...
3
votes
1answer
206 views

Exchange axes in ListLinePlot

I'm sorry to do this right off the bat, but I have the following set of data: ...
2
votes
2answers
122 views
2
votes
3answers
143 views

Join matrix based on conditions

Given the following matrix: ...
2
votes
2answers
59 views

Specifying an array with a specific number of copies of two elements

To specify an array of length L in Mathematica, where each entry is someElement, I'm accustomed to writing: ...
2
votes
3answers
427 views

Generating pairs of additive and multiplicative factors for integers

Given an integer $n$, I want to get two lists: a) the set of pairs of the divsors $a,b$ into exactly two factors $n=a\cdot b$, b) the set of pairs $a,b$ of two summands $n=a+b$. The code I ...
2
votes
0answers
310 views

Generating a function which outputs possible chemical reactions

I want to make a list of chemical reactions and I write them down in a $\require{mhchem}\LaTeX$ format. They are of the following form $$NA_n^i+MB_m^j \rightarrow \hat NA_{\hat n}^{\hat i}+\hat ...
2
votes
3answers
222 views

Taking only particular subsets and doing calculations

I have subsets formed from a list using the Subsets command and want to do a particular calculation, lets say subtraction using the ...
2
votes
2answers
2k views

Calculating the distance between the coordinates in a list

I have a list of coordinates {{A[9, 4, 7], 0.0395174}, {A[1, 5, 0], 0.0163797}, {A[0, 7, 2], 0.0577425}, {A[2, 7, 5], 1.01313}} I want to find the distance ...
2
votes
2answers
292 views

Pattern test for variables during function definition

I am having a problem with pattern testing on variables during function definition ...
2
votes
1answer
172 views

List-operations only when restrictions are fulfilled (Part 2)

Consider the following: data={{{3544128000, 80}, {3544732800, 80}, {3545337600, 80}, {3545942400, 80}, {3545942400, 160}, {3546547200, 160}, {3547152000, 0}}}; ...
1
vote
1answer
100 views
1
vote
1answer
212 views

Compile with array operations

When I use the function f with only the Module ...
1
vote
1answer
155 views

Selecting every last element of a nested list

I couldn't find a similar question so I decided to ask this one. I have a nested list with many sublists of equal length. To make things easier let's say it's like that: ...
1
vote
1answer
116 views

Format Preservation of FullSimplify on Indexed System of Autonomous Equations

I currently have a large system autonomous differential equations. I've indexed a more managable dummy system of identical form, using Part to reference each ...
1
vote
3answers
172 views

Separate an array in two arrays, the even and odd terms being separated in these two arrays

How can I separate the odd terms in one array and the even terms in another array,i.e., go from a={1,2,3,4} to aeven={2,4} ...
1
vote
2answers
222 views

Thread over a nested list top to bottom until non-list elements are found

I have a nested list: list = {1, 2, {3, 4}, f[a], {2, h[b]}} I would like to apply a function g to all elements of the ...
0
votes
1answer
37 views

save all inputs as list [duplicate]

I received three results of calculations: {k->0.190729} {k->0.197575} {k->0.249319} Could you help me write the results in the following form: ...
0
votes
1answer
105 views

A problem with set values

The following code is just an example to clearly explain my problem. Assume that : ...
0
votes
2answers
117 views

Total elements of a list that have a common first element [duplicate]

Possible Duplicate: List-operations only when restrictions are fulfilled (Part 1) I have a set of data like: ...
21
votes
5answers
515 views

More efficient way of generating list of occurrence counts?

Given a list, e.g., target = {a, b, c, b, c, d, c, d, e, f, a, h, g}, I want to generate a list containing the occurrence count of the corresponding element of the ...
16
votes
4answers
3k views

Finding Local Minima / Maxima in Noisy Data

I'm trying to find local minima / maxima in noisy data, consisting of data values taken at certain time intervals. Ideally, the function should take a pair of lists (one containing time values and one ...
27
votes
4answers
921 views

Filtering beat-to-beat heart rate data

From an experiment, I have a dataset of beat-to-beat heart rate data: a list of the time between each heart beat in [ms]. The data is measured using an infrared optic sensor at the finger tip. The ...
20
votes
15answers
1k views

How do I extract the middle element(s) of a given list?

How do I extract the middle element(s) of a given list? Here is some code that works, but seems a little too long: ...
19
votes
3answers
783 views

How to extract the edge from a set of points

I have an accumulation of points representing a body as you can see in the image below. From this data I want to generate a list of points or a curve, which is the envelope. The first idea was a ...
17
votes
1answer
347 views

Underlying Algorithms for List Manipulation Functions

Does anyone know, or know of a link for the underlying algorithms used for list manipulation functions? Specifically: Union with and without the ...
19
votes
6answers
6k views

How to find the position of elements in a list satisfying criteria

Say I have a list x={2,4,6,8,10} and I want to find out the positions of the elements that are greater than 7. ...
21
votes
5answers
6k views

How to find the phase difference of two sampled sine waves?

I'm trying to measure a phase difference between two Sine functions I've acquired with a computer. I'm uploading one of the .txt files with the data I'm working with here: txt file. To remove the ...
27
votes
2answers
699 views

DeleteDuplicates not deleting duplicates

It is not surprising that DeleteDuplicates[{5,5.}] returns {5,5.} because DeleteDuplicates ...
17
votes
4answers
294 views

Setting parts of a list

Suppose I have list a = Range[10] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} in which I want to set some elements to be a list ...
12
votes
10answers
603 views

How can I generate a nested array like this one?

Well, this is how the array looks like: I came up with this code: n = 10; Nest[ArrayPad[#, 1, 1 - #[[1, 1]]] &, {{1}}, n] /. {1 -> "*"} Any better ...
11
votes
2answers
198 views

Bug with SparseArray selector in Pick

I have created a notebook with two cells. This is the content of the first: ...
8
votes
4answers
271 views

Searching linked lists that contain lists?

Following the advice I've read here and other sites, I've been trying to use the Mathematica equivalent of a linked lists... ...
18
votes
3answers
721 views

Strip waste braces in nested list

I have nested lists wherein there are a lot of waste levels which looks like l = {{{{{{2, 2}}, 3}, 2, {{2, 33}}, 4, 5}}}; I would like to reduce it to somthing ...