# Tagged Questions

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

162 views

### Rearranging a set of numbers

I have this set of numbers, that is a range of prices (ie 6-10) and a quantity of products (5) ...
143 views

### Creating a list from other lists and varying the number of elements that get added

Suppose I have listA = {M, F} and ListB = {a,b,c} I want to make a new ...
231 views

### Function[] argument nesting for operations like Select[]

The following code selects a special element from a list thelist = {"this", "notthis"}; Select[thelist, (# == "this") &] What I want is a function which ...
90 views

### Inverse action of Thread

I cannot find the original post now, but I'm quite sure that there's an amazing post teaching us how to do Thread on ragged lists. but my problem is how to inverse ...
92 views

### remove unevaluated cells from table

I have created a table Tv where each row is of the form {x, y, Iv[x,y]} where Iv is some complicated numerical integral and <...
74 views

### Implementing the Cimmino method [closed]

What am I doing wrong? I am trying to implement the Cimmino method, an iterative method for the solution of linear algebraic systems. The final output should be a vector. Here is a description of the ...
124 views

### Plotting a table with many y values

I'm trying to plot a bifurcation map for a Lorenz System. I have a function (called estables in the code that follows) which, for a certain value r, returns the ...
137 views

### Find the length of the intersection of two lists including duplicates

I have 2 Lists. The first one includes all the numbers from 1 to 10. listA={1,2,3,4,5,6,7,8,9,10} The second includes ...
70 views

### Calling results of applying f to expr inside NestList

Being new to Mathematica, I try to follow the suggestions of using NestList, Map, Table ...
70 views

### Calculate Cumulative Mean and Standard Deviation of a list without FOR loops [duplicate]

I have a simple list mylist={x_1,x_2,...,x_N};. Now I want to map a function over this list, e.g. the Mean and StandardDeviation functions, so that it will give me ...
101 views

### How to gather a list whitout no repeat element to nearest a certain number

Background: The question derive from this question.But some criteria is omited by me.So I try to post a new question for this.If my expression is dimness and you have got it,just tell me or edit my ...
39 views

### Setting initial conditions of a domain grid?

So I'm writing some code to try and produce a cellular automaton which will model an oscillatory chemical reaction, but I'm trying to set up the initial conditions of the grid so that I can vary them ...
90 views

### How do I convert Subscript[{4, 5, 1}, 7] to the integer 4*1 + 5*7 + 1*7^2 = 88?

I am working with the finite fields package in Mathematica 9. If I input: GF[7, {-2, 0, 0, 1}][{3, 4, 1}]^2 Mathematica gives me $\{4,5,1\}_7$. I want to ...
85 views

### Solving a list of equation which takes so much time

I try to solve a list of equation in a following way but it Mathematica solves equations after 30-40 minutes or don't solve them at all. The functions that I use are ; ...
202 views

### Tracing 2d coordinates by using Nearest function

In 5 digital images I have determined the 2d coordinates of detected objects. The resulting coordinate list can be downloaded from here: http://pastebin.com/7bE0CEJ5 ...
118 views

### How can I make custom accumulated sequences like the following?

First of all, I don't really know how to formulate the question, so if you understand my question and know a better way to phrase it, please revise. I have the following Matrixes: ...
63 views

### How do you add one chart to the right of another? [closed]

I have two charts, and I would like to insert the data from one at the end of the other. However, the one chart has multiple ListLinePlots, and when I use Show to try and place the two together, the ...
196 views

### Animating N points

So I'm trying to create an animation of N interacting particles in two dimensions confined in a box. Generating the data is fine and it's being stored in a text file with two columns for each particle;...
60 views

### How does levelspec work inside Position?

Please, can you explain the following feature of levelspec inside Position ? This code test=Range[5]; Position[test,x_/;x>2] as expected, gives ...
130 views

### Programming a MaxMin Linear Optimization

I want to program a function for a two-player game. Basically it's like this: . Each player has an array of options, and the result of the game is based on both players choices. So heres my most ...
44 views

### Simplifying nested KroneckerProducts

Any suggestion how to bring a nested KroneckerProduct form into just one? I mean some how converting ...
83 views

### (Again) eliminate curly brackets from PopupMenu?

How can I display the items in a PopupMenu , which is fed by a list, without the curly brackets? The sample code is: ...
626 views

### Use a part specification as the argument to a compiled function

I have some code that needs to generate a large matrix based on some complicated combinations of smaller matrix elements. I find that if I write a function for the element of the larger matrix, and ...
99 views

### Count two or more equal consecutive elements in a list and create histogram

I have a list generated by: list = RandomInteger[{1}, 100] it contains only 0's and 1's ...
96 views

### Retaining relative sizes of local maxima using MaxDetect[List]

I would like to be able to find the position of the two greatest local maxima in a list. For the example: list={1,2,3,4,2,1,2,6,5,4,3,2,} I would like to return <...
103 views

### Combining $n$ lists [closed]

From this question, I know how to combine two lists. In fact, if $X_1,X_2, X_3$ are lists with the same length, then the command Transpose[X_1,X_2,X_3] will work in ...
102 views

### Average list of list of parameter values [duplicate]

I have a list of lists of fitted parameter values, e.g. list={{a->1,b->10},{a->2,b->20},{a->3,b->30}} (the actual parameter names can vary, as ...
166 views

### Replace missing data

I have vectors of equal lengths where I want to replace the zeroes (missing data) with their preceding values. So far I have written: ...
211 views

### Functional programming approach to avoid traditional loops

I'm currently learning from the wonderful post: Where can I find examples of good Mathematica programming practice? And i'm correcting my habits using Nest/Map/Thread instead of loops. The problem ...
126 views

### Given a list made up of subsets of an alphabet, how can I use associations to create a Boolean dictionary of the given list

I have a list of 30,000 elements, each of the element is a list in itself {{a, b}, {p, q, r}, {a, p}, ..., {z, x}}. Second one contains unique elements ...
166 views

### Calculate efficiently an expensive hermitian matrix

I want to compute a matrix $M_{pq}$, for which the calculation of each coefficients $M_{pq} = f(p,q)$ is an expensive function. I know that my matrix is hermitian, so that $M_{qp} = M_{pq}^{*}$. As a ...
242 views

### Trouble with Position[] [duplicate]

I am in trouble with Position, Although my example works as expected it throws a warning. Position[{{a,b},{a,c},{a,b}}, _?(#[[2]]==b&), {1}] During ...
160 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 ...
401 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} ...
158 views

### Programming for matrix manipulation

I want to write a programme which operates on nd x nd matrices. The programme looks the matrix as a n x n block matrix where ...
67 views

### Fast functional method for multiplying duplication numbers in a large list

Consider a list of symbols: mySet = {a, b, b, c, a, b, c, d}; I would like to form the product of duplication numbers. In the example above, I have 2 ...
131 views

### Partition a list dependent on consecutive list values

I have a list of 2D points which I partition every time the distance between consecutive list elements is bigger than a certain threshold. In a second step I select all the lists that start within a ...
192 views

### Working with calculations that depend on the previous value in a list

I'm trying to make calculations on a list that depend on the previous value. In my case I'm doing event detection - detecting the point where a value rises above some threshold for the first time e.g....
127 views

### How to efficiently select elements from a Hash?

How can I write an efficient version of the following selection statement: Keys[Select[hash, # < constant &]]; // AbsoluteTiming hash can be made from: <...
1k 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, ...
152 views

### Change all values of a series to positive values

I would like to change all values of a series to positive values. I refer to my previous question, answered in the most part, very elegantly by RunnyKine. However, there remains a slight glitch that ...
194 views

### Write list of polynomials as a matrix of coefficients times a list of monomials

I have the following problem: given a list of polynomials P = {p1, ..., pn} on the variables x[1], ..., x[n], find a list of ...
136 views

### Incrementally revealing Grid (or TableForm) entries

I have a Grid (or TableForm) object like this ...
937 views

### A rotation-like transform on a matrix

Do not be confused with comments, those are for previous version of the question - Kuba Imagine I have a matrix of the form: ...
201 views

### Combining the items with common available dates from two lists [duplicate]

I have two lists of data including dates such as data1 = {{{yy, mm, dd}, a}, ...} data2 = {{{yy, mm, dd}, A}, ...} There are some missing dates from each list, ...
425 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 ...
331 views

### Deleting a row or column of an adjacency matrix while maintaining the associated label

I am currently working with a weighted adjacency matrix for a directed graph, and it contains several 0 columns and rows. With the unaltered matrix, I am able to monitor the relations between vertices ...
217 views

### How to efficiently take complement of two big lists?

I have a giant list l1 and some smaller lists l21, l21, ..., ...