# Tagged Questions

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

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### List within a Do loop, I can't get any values [duplicate]

I am having the following problem. I am trying to get some values from solving an equation and apply them into a list but in the output I get nothing but the symbol of the variable... The code is as ...
218 views

### Why SetDelayed won't work

I'm trying to do this: Riffle[list = {a, b, c, d, e, f}, tem = RandomInteger[1, Length@list-1]] {a, 0, b, 0, c, 1, d, 0, e, 0, f} But I think this method is ...
201 views

### Creating Nested For Loops for modifying values to append to a List

Basically, the title says it all. I am familiar with python, not so much with mathematica. For the program, I am starting out with three unique lists of values for which I am using a triple nested ...
33 views

### Envelope of a given table (or plot)

Is there any way to construct an envelope of a given table (list) or plot? For example, I have plotted (used ListPlot of txt-file) And then I want to plot the envelope (upper or lower) of this plot ...
29 views

### Find same list elements of two lists [closed]

Example: I have two 2D lists (each list has no duplicate elements): l1 = {{1, 1}, {2, 2}, {3, 3}, {4, 4}}; l2 = {{1, 1}, {3, 3}, {5, 5}}; How can I create a new ...
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### How to ListContourPlot a functional eigenvalue spectrum?

We have a (Hermitian) matrix of some finite dimension (n) whose elements are functions of real variables x and y. We wish to plot contours of the spectrum (level sets of the n real eigenvalues) at ...
78 views

### Function that counts number of consecutive elements after iterator in Table command

I have a 1D Table, something like this, that I want to turn into musical notes: ...
163 views

### Nonzero element positions of a matrix

Let m={{1, 2, 0}, {4, 0, 9}}; I want to find the position of every nonzero element of the above matrix. The code ...
284 views

### How to mesh a region using adaptive cubic elements

Assume a list of {x,y,z} coordinates. The coordinates are arranged in a regular fashion through a fixed raster size (called ...
295 views

### What is the most efficient way to replace items in a list at periodic intervals?

For example, if I want a list of $\phi(n)$ for $1 \leq n \leq 100$ but if $n$ is a multiple of 3 I want to show a 3 instead of $\phi(n)$. I tried ...
42 views

### How to solve from a list

I have this equation: $y(t)=aE^{-bE^{-ct}}$ and I have this list: ...
113 views

### How can I extract the x and y values from a coordinate pair? [closed]

I think the question says it all. I have a coordinate pair, {x,y} and I want to extract x and y for use in further calculations. Can't find anything in the docs about this but it seems like it should ...
55 views

### How to combine 3 list together in a form like this {x,y,z}

have a list like this ...
111 views

### Differentiating between zero and “empty” in lists, and adding them?

(Edit: I mean 'differentiate' as in telling the difference between two things, not as in f'(x) ) I have n series of numbers, let's say two for example, with some "empty" spaces between the numbers, ...
123 views

### Assign a list of sums to indexed variables

I want to generate a list of sums {a, b, c, d, ..., z} and assign them to a list of variables such that ...
73 views

### Import Excel sheet into 3D array, 1st row and column as x- and y-axis

It might be simple, but for me, it took several hours working on, but still cannot figure out. Basically, I'd like to create 3 dimensional list data ({x,y,z}) from excel file, so I can plot them ...
55 views

### positions satisfying pattern and grouped

I have a list of numbers and I am looking for a way to most efficiently find positions of values that satisfy a certain condition and group those positions that are sequential. To illustrate, a simple ...
84 views

### How to get a C4-symmetric (coincides after 90° rotation) matrix via ImageData from Graphics?

I tried an easy example with Disk centered at {0,0} with radius 1. Obviously, that object is C4-symmetric. Further, ...
129 views

### Insert a symbol include first and last position [closed]

Assume we have a list list = {"a", "b", "c", "d", "e", "f"} Then use this code: StringRiffle[list,"*"] But ...
77 views

### Joining table of tuples with table of scalar values [closed]

I have a table of dimension $M \times N \times Q$ of 3-tuples {x,y,z} that represent points, and another table of dimension $M \times N \times Q$ of scalar values. ...
24 views

### Finding the percent difference between elements of a matrix and a list/vector [duplicate]

I have a large matrix of 24 columns, 11 rows, and a vector in the form of a one column, 11 row table. What would be the best method of finding the percent difference between each element of the matrix ...
63 views

### overlap of data

I have two individual Date lists as Date Objects: List 1 = {1 Jan 1991 9 :00 , 3 Jan 1991 11:00 ..etc } List 2 ={ 7 Jan 1991 14:00, 9 Jan 1991 15:00 ..etc} For ...
123 views

### Arc length parameterization of a list of points?

Suppose I have a curve represented by a list of points in the form $\{\{x_0, y_0\}, \{x_1, y_1\}, ...\}$. How to generate a list of numbers $\{s_0, s_1, ...\}$ where $s_i$ is the distance of ith point ...
82 views

50 views

### How to deal with repeating usage of same attributes

I am producing in my notebookfile many plots with the following example code: ...
48 views

### Corresponding list value and index in a list

I have a list and I know the maximum value of that list by using Max[list]. The thing is I want to find out the index number of this list that corresponds to this ...
207 views

### Group list elements in sequence

Suppose we have the following list: list1={1,2,4,6,8,9,10,14,15,17,21,22,72,76,80,96,106,116,117} Actually the real list has about 100K elements. What I want to ...
126 views

### Assigning to multiple variables in a list the values in another list

I have two lists, one contains the variables and the other the corresponding values that the variables should take. ...
136 views

If I define ...
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### Transform {x,y,…} and {a,b,…} in to {x->a,y->b,..} [closed]

How to merge two list and add -> to it. For instance, I have {x,y,z,...} and {a,b,c,...} ...
67 views

### Adding +2015 to each value of my x-axis [closed]

I want to change all of the values of my x-axis by +2015 The problem is, I evaluated a large expression using incremental values {i,1,85} and plotted that data. The Plot's x-axis is 1 to 85, as ...