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

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3
votes
4answers
291 views

How to improve the quality of the ListPlot output

I need to plot massive data stored in external ASCII files. Below is the Mathematica code I use for this job: ...
13
votes
10answers
647 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 ...
3
votes
2answers
306 views

Modify all the second elements of every pair in a list of pairs

I have a list in the form {{a, 1}, {b, 2}, {c, 3}}. Let's say I want to operate a transformation on all the second elements of each sublist, but this transformation is a function of them all together....
17
votes
6answers
732 views

How do I replace a missing value in a column with the value immediately above throughout a table?

I have a large table (7000 rows × 17 columns) of terse textual data. In many of the columns, empty entries have been replaced with "." as a marker. Working from the top of the columns downward, I want ...
14
votes
7answers
857 views

A function that accepts a pair or a list of pairs

Probably a duplicate, but it's not easy to search on "lists". I have a function that accepts a list of lists, say {{a1, b1}, {a2, b2}, {a3, b3}} and performs some ...
8
votes
5answers
362 views

Wrapping a function in count

I am working through the Programming Paradigms via Mathematica (A First Course) and am attempting to answer the following: Use recursion to count how many times the argument can have its square ...
21
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: ...
5
votes
1answer
198 views

What is the fastest way to maintain a large set of expressions?

In my algorithm I need to maintain a set (an unordered list of distinct elements) of expressions supporting two operations: Test an expression for membership in the set Adding a new expression to ...
2
votes
1answer
68 views

Adjust the results of evaluating Table so it can be used as a argument to Point

I have a list generated by Table as below. ...
0
votes
1answer
123 views

Displaying Values of Fuction at end of Period by Grid

My intention is to place the values of two function into a small box within my chart. To be more precise I have two vectors. A meanvector which shows the average value of all simulated stochastic ...
1
vote
2answers
369 views

Scatterplots for subsets of multivariate data [Updated]

Update/Re-write There has been a lot of ambiguity over what i'm am trying to do with this question so I have decided to give it a full rewrite. I'm really sorry for the confusion. If you want to see ...
10
votes
4answers
552 views

Partitioning a list by recursion (Programming Paradigms via Mathematica (A First Course))

I am working through the course Programming Paradigms via Mathematica. One of the homework exercises for the section Recursion I: Passing the Buck is as follows: Use recursion to partition a list:...
5
votes
4answers
795 views

Combining the second elements of a set of ordered pairs based on their first element [duplicate]

I have a large set of ordered pairs and I am trying to add the second elements together for any group of pairs that has the same first element. For example my data looks like: ...
0
votes
1answer
204 views

Stopping- threshold and stopping- time of stochastic processes.

Rod Lm helped me to generate the following code, which I want to extend a little bit. So my intention is to use the threshold (the green line) as boundary in the following way: as soon as the process ...
1
vote
1answer
177 views

WeatherData acquirement in ListStreamPlot

I am trying to show the wind streams in a geographic area as following code for a range of time.Even if it works for realtime data but it doesn't work for range of time.I am filtering and also taking ...
0
votes
1answer
230 views

Brownian Motion with stopping threshold

I just want to generate one stochastic process, whereas I want to be able to manipulate the start value and the volatility. Furthermore, the process should stop when it reaches 5 However, as soon as ...
2
votes
1answer
123 views

order items of a table

I am trying to change order of a table. ...
1
vote
2answers
129 views

Select elements in a list when the firsts two items are the same (no matter order) and its third element is lower

I'm trying to solve a heuristic search in Mathematica 9. I get a list of succesor nodes called open with two nodes and a heuristic value, e.g., ...
1
vote
1answer
112 views

Expand list of {{t1,x1},…} with new set of t's

I have a list of the form data={{t1,x1}, {t2,x2},...} and a list newt = {nt1,nt2,...} and I want to expand ...
0
votes
1answer
359 views

ListVectorPlot3D

I try to plot a 3D Vector plot. All Vectors start at (0,0,0) and point in directions given in spherical coordinates: ...
0
votes
1answer
224 views

Problem with importing format of data from Excel?

I am trying to import data from Excel. It is located in a single column of the Excel file but each cell contains a comma separated pair of two values as a,b. When I am importing them I have this ...
2
votes
3answers
389 views

Introduction of straight Line into Manipulate function

I just want to implement a line within my chart that starts from time point 0 to time point T and whose y-coordinates can be manipulated, which in my case is represented by D. I tried to implement a ...
0
votes
1answer
105 views

Sublist inside simple list

I have a doubt to confirm. Let there is a list f = {{l}, {c}, {d}, {e}, {1, 2, 3}, {3, 4, 5}} And I expect it to be traversed as a normal list which I can do ...
4
votes
2answers
126 views

Specific rearrangement of elements in list

I have an $n\times n$ matrix G with elements g[i,j] that I construct with ...
0
votes
1answer
99 views

Making a list from equations

I want to make a list (efficiently) which is the set of lattice solutions of the following equations (depends on $k$): $x_0\geq 0$ and $x_i\in [0,4k]$ for $i=1,\ldots,4$ satisfies $x_0+x_3\leq k+3$, ...
0
votes
1answer
215 views

Problem with ListContourPlot feeding data format and WeatherData

With following code I am trying to show the mean wind speed patterns for a few geographic locations. ...
1
vote
2answers
824 views

How to find the position of non consecutive numbers?

Given a sorted table, how can I find the position of non consecutive numbers in the first column of the table? ...
3
votes
1answer
430 views

Removing sublists containing elements from another list's sublist

Let there be two lists that have sublists: a[] = {{1, 2}, {1, 2, 3}, {2, 3, 4, 4}, {3, 4, 4, 5}} and ...
4
votes
3answers
205 views

Renaming and indexing list of rules

I have a list of rules that represents a list of parameters to be applied to a circuit model (Wolfram SystemModeler model): ...
7
votes
2answers
264 views

Programatically adding/retaining comments within a nested list

Is it possible to convert the following list of strings to computable numbers with the comments preserved? ...
5
votes
6answers
379 views

Selective thinning of string elements in nested lists

I have a nested list similar to this example list (but much bigger and more messy): ...
0
votes
1answer
1k views

How to calculate the area of a listplot [duplicate]

I need to calculate the area enclosed in a two-dimensional listplot and following an answer to a similar question I tried this way: ...
2
votes
1answer
699 views

How do I sort complex numbers?

Okay, so I posted something about sorting, and it was linked as a duplicate to This post However, I am having problems trying to sort a list that contains both real and complex numbers. I put them ...
1
vote
3answers
158 views

How to convert a spaceless data into tab delimited

I have a data set in form of:(this is just an example) 1324501020 3241030205 4332020134 the data are stored in a text file (e.g. data.txt) but I need to convert ...
9
votes
3answers
389 views

Numbering nested list according with Depth (or Level)

(This question is slightly similar with Sequentially numbering a nested list, but not exactly the same.) What I want Say I have a nested list ...
1
vote
2answers
195 views

Indicating the probability that a weather datum is above/below some given value on a geographic map

With help of the previous questions here, I am analyzing weather data as daily MeanWindSpeed of some cities with the following code: ...
1
vote
1answer
107 views
2
votes
2answers
448 views

Create list via checkboxes

I am trying to achieve the following: Three (dynamically updated) Checkboxes (a, b and c) can be toggled on or off individually. Depending on their status, a ...
1
vote
1answer
136 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 ...
17
votes
1answer
243 views

Why changing list's head takes time?

Consider AbsoluteTiming[Range[10^7];][[1]] 0.035000 and AbsoluteTiming[HoldComplete @@ Range[10^7];][[1]] 0....
4
votes
1answer
79 views

Optimizing List Multiplications

I've got a list manipulation optimization problem. Consider a two-dimensional nxm list list1, and a three-dimensional nxmxm list, ...
1
vote
0answers
72 views

Sorting Eigensystems [duplicate]

SO I have this code: ...
3
votes
3answers
230 views

Plot sublists as different colors

I have one big list with many sublists inside. All sublists consist of three numbers. For example: ...
3
votes
1answer
140 views
3
votes
1answer
139 views

Filtering the elements of an array to split them into two categories

So, I am new to Mathematica, and I am trying to write something that involves taking values from one array and separating them into two different arrays. My code for doing this is: ...
1
vote
2answers
247 views

Counting a cardinality of a subset satisfying special property

Suppose that we have a set of 9 2-dimensional vectors $c$ by m=3; n=2; c=Tuples[Range[m],n]; We want to define a subset $S$ of vectors in $c$ by the following: ...
4
votes
2answers
2k views

Function returning Null along with other unexpected expressions

When I use some function, at the end along with the output I get some NULLs returned that I don't understand the reason for and are highly undesirable. For example, when I define the reversal of list ...
4
votes
1answer
303 views

Generating a list of all factorizations

What is the best way to generate a list of all factorizations of some number $n$? I'm quite new to Mathematica so this might be obvious. I have been trying some basic stuff with ...
3
votes
1answer
224 views

Indexing of Large Autonomous System of Equations for Use in NDSolve

I currently have a list of ~150 autonomous ODE's that I need to be able to work with using NDSolve. Fortunately I already have them formatted in plaintext, which ...
5
votes
3answers
257 views

Applying a function with the HoldAll attribute inside NestList

I'm trying to write an update function, which can be applied to a list and then to NestList it. As the function has to manipulate the given variable I figured I ...