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

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3
votes
5answers
514 views

Randomly selecting and reinserting a subset of elements in a list

This question is similar to my other question: How do I randomly select 'k' positions in a list and shuffle their respective elements without effecting the other elements? Imagine first a ...
3
votes
3answers
213 views

Finding a better way to define a matrix

I first defined a 171x171 matrix containing only zeros and then replaced 18 specific rows with nonzero entries. The other $153$ rows will be average of $2$ of the existing $18$ rows. Rows $2$ ...
3
votes
2answers
242 views

List manipulation after importing txt-file

I have some problems converting data which I imported from a txt-file into proper Mathematica expressions. After importing my data looks like ...
3
votes
4answers
240 views

Finding the location of the last day of the month in a list of dates

My question differs from earlier questions about getting the eom dates from a list; I want to get the position of those dates so I can get the corresponding values from other lists. My problem seems ...
3
votes
2answers
307 views

Replacing values above a threshold with 1 [duplicate]

I have a list with some values and I want to replace a value which is greater than 1 with 1 otherwise keep the value. In this case 10562: ...
3
votes
3answers
187 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
3answers
188 views

Count items in a list that occur before a date

I have a list of dates that happen throughout 2013. I wish to construct a graph showing a cumulative total of elements that happen before that date. I have a working algorithm, but it seems too slow ...
3
votes
2answers
169 views

Subscript and Part: What's going on in this example?

Example I came across the following simple example from A Beginner's Guide to Mathematica, by McMahon and Topa, which I believe was written circa version 5.2. (FWIW, I'm using v9.) ...
3
votes
2answers
1k views

Trying to generate a list of data to plot a graph with error bars. Need help creating the looping function

This is the sets of data I want to put into a form which will allow me to plot error bars from the min and max data. ...
3
votes
4answers
178 views

Building intervals

I'm facing the right know the problem of building intervals to an arbitrary number. The special thing is that the first and the last intervals should have fixed length, while the "middle" ones should ...
3
votes
3answers
273 views

How can the lowest non-zero value in a nested list be found and its position in the sublist returned?

In the example code below we have a list of triples that produce one or more sublists with at least one zero value. How can the positions of the lowest non zero value in each sublist be returned ...
3
votes
3answers
192 views
3
votes
2answers
390 views

Convert a list of hexadecimal numbers to decimal

I know that to change a single number from hexadecimal representation to decimal, you can use: base^^digits. However, if you have a list of numbers, Mathematica ...
3
votes
3answers
154 views

List manipulation: Dropping first or last row or column of a matrix

How do I drop the first/last row or first/last column from a matrix? The general case is answered here but I am new to Mathematica and it the arbitrary case is unnecessarily complex. Suppose I am ...
3
votes
2answers
110 views

How to define a list of symbols as a list of functions?

I have a list in Mathematica for example P={1+t,1+t+t^2,1+t+t^3}; My question is, how I can define each element of this list be a function of ...
3
votes
3answers
181 views

Breaking up combined data into several smaller data sets

I have one combined data with first number as the x-value and the remaining as different y-axis values (y1,y2,y3...). How do I break this combined list, data= (x,y1,y2,y3...) into smaller lists, such ...
3
votes
3answers
196 views

Zero-order interpolation not going fully around

Connected to this question, I want to do a zero-order interpolation of a bunch of datapoints which is periodic. The code I use is as follows: ...
3
votes
3answers
247 views

How can I extract multiple spans from a list?

I know in Mathematica, I can do A = Range[100]; B = A[[50 ;; 60]] B will then contain the 50th through 60th elements of A. Now, what if I wanted B to take 10th ...
3
votes
4answers
239 views

Delete Missing data from coordinate sets

I have a list of pairs of coordinates, where some are missing. ...
3
votes
1answer
198 views

How can I find the average of the ordinate of an indefinite number of lists of points?

Suppose that I have three lists: list1 = {{0, 1}, {0.1, 10}, {0.2, 100}}; list2 = {{0, 1}, {0.1, 10}, {0.2, 100}}; list3 = {{0, 2}, {0.1, 20}, {0.2, 200}}; In ...
3
votes
2answers
250 views

Using the elements of a subset in a Do loop

I would like to use the elements of Subsets in a Do loop. I have: ...
3
votes
5answers
121 views

How to filter list of list of rules on certain condition?

For example, Solve[] returns all solutions as a list of list of rules. And mine looks something like this: ...
3
votes
3answers
118 views

Max function used with nested lists

I have a list as follows lis1={{{1,5,6},{4,7,8}},{{1,2,2},{5,6,7}}} and would like to calculate the max value of each nested list in order to get following ...
3
votes
2answers
108 views

Generating Z^*_n

I'm using Mathematica to illustrate basic number theory concepts in a graduate cryptography class. To generate elements of the multiplicative group of integers modulo $n$, i.e. $\mathbb{Z}^*_n$, I can ...
3
votes
4answers
120 views

Use a categorical argument to add one layer of list structure

Consider the following nested list x = {{1,2,a}, {3,4,a}, {8,11,b}, {12,3,a}, {4,3,b}, {3,2,c}} I want to use the categorical variable ...
3
votes
2answers
107 views

Sublists of Random Permutations

What is an efficient way to create a list of (psudo)randomly chosen permutations? I'm trying to create a list like below: ...
3
votes
5answers
148 views

Creating a new list by dropping sub elements of the original list

Suppose I have a nested listed as follows, {{{1,2},{3,4,5},{2,3}},{{2,3,4},{5,4,1},{1,4,3}},{{3,4,5},{3,4,5}}} Where the elements are, ...
3
votes
2answers
296 views

Finding positions of multiple elements in lists

I realise that Position[{2, 4, 8, 16, 32, 64}, 4] will return {{2}} I would like to do something like this: ...
3
votes
2answers
756 views

How can I scale the y axis?

I have a file I import and read into a table of $2 \times n$. I can plot this data using the following code: ...
3
votes
6answers
348 views

Compute ratios of elements in two lists

I have two lists, say a and b, both of length n. I'd like to compute the following: ...
3
votes
2answers
109 views

Manually accept elements of a list

Let's say I have a list like: {"good element 1", "bad element 1", "good element 2", "good element 3", "bad element 2", ...} I would like to build a function that ...
3
votes
5answers
484 views

Elegantly adding two differently spaced lists of ordered pairs $(x, y)$

Suppose that I have two lists, list1 and list2, of ordered pairs $(x, y)$. The two lists are differently spaced in $x$; some ...
3
votes
2answers
338 views

Colors associated to parts of a 3D distribution of points

Suppose we have a long list of random points (cartesian coordinates) in 3D space. coords := ...; Until now, I was associating colors in a radial way, from the ...
3
votes
4answers
343 views

How to change a value within a list of lists?

I essentially have two questions, both are related. 1) How do I change a value within a list of lists (I provided a example problem)? 2) Why does my code not work? I have a list which was created ...
3
votes
2answers
571 views

How can I transform a list of binary digits into integers?

I want to transform a list of binary digits into integers. With the Table function, I produce four lists of binary digits of length 32. Then I tried to turn these ...
3
votes
1answer
3k views

Filtering Lists in Mathematica [duplicate]

Possible Duplicate: Select/Delete with Sublist elements? I need help in filtering long lists of x,y coordinates.Lets use the following list as an ...
3
votes
3answers
264 views

Are table headings functional?

Are table headings for aesthetics only? If I have: ...
3
votes
1answer
176 views

Efficiently keeping elements in a list (an input list) that exist in another list (a keep list)

I have some code that generates lists of integers (one such list is called, for example, inputList). I also have a "master list" of integers that should be kept, ...
3
votes
2answers
362 views

Pattern test for variables during function definition

I am having a problem with pattern testing on variables during function definition ...
3
votes
2answers
117 views

Plot 2d-ItoProcess data in a plane

I am trying to simulate a simple 2d Ito SDE (randomly perturbed Hamiltonian system). Below is the code. ...
3
votes
2answers
72 views

How to re-arrange lists, divide one list into 2 lists with a particular step [duplicate]

How to re-arrange following list: {a1,b1,a2,b2,a3,b3,a4,b4} or this {a1,b1},{a2,b2},{a3,b3},{a4,b4} to get: ...
3
votes
1answer
194 views

How can i subtract a surface from another

I have one surface which i got with using analytical solution. And one by ListPlot3D. My question is how can be withdrawn from the one from the another. ...
3
votes
2answers
90 views

Combining sub-matrices by replacing zero elements with symbols

I have a nested matrix as m: ...
3
votes
3answers
133 views

How to pick the maximum of a list? Improving efficiency

I need to find the element of a list, with the highest weight. Example: ...
3
votes
2answers
234 views

Binarizing a matrix

I have an image with a few bright pixels with the remaining ones very dark. The difference is in orders of magnitude. I want to binarize this matrix (corresponding to the image) making all values ...
3
votes
1answer
123 views

Sectional averages of a list

I am working in Mathematica. I have a table of 200 elements. I want to calculate the mean value for the first 20 elements, for the second 20 elements and so on, up to 200. I will get a table (matrix) ...
3
votes
1answer
572 views

Converting truth tables to boolean expressions

I have a truth table for a Boolean expression represented like this ...
3
votes
1answer
172 views

How to make a simple tree yourself with defined distances for each generation?

I'm trying to make a function that generates a tree for spin spin analysis in spectroscopy. I though it would be pretty easy, but I'm totally stocked. The tree should look something like this: ...
3
votes
1answer
538 views

Removing an ordered pair from a list of ordered pairs if the second element in the list is Less than a Value

I have a list of ordered pairs from a piezoelectric sensor sampled at 2kH. The first element is time and the second, amplitude. I'm trying to remove all ordered pairs in the list of ordered pairs when ...
3
votes
2answers
593 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 ...