# Tagged Questions

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

509 views

### Minimum in a nested list [duplicate]

I have a nested list of {x,y,z} and I want to find out the values of x and y where z is minimum. I can write a nested For loop and do it ...
234 views

### Non-descending Tuples

I want to get all the non-descending tuples of a list with given length, for example: f[{1,2,3,4},{3}] ...
587 views

### Replace a column in table with a list of numbers?

I have a Table of values e.g. {{x,y,z},{x,y,z},{x,y,z}…} How do I replace the the "z" column with a List of values?
450 views

### Visualize a tree structure using TreeGraph

I have a code that generates a tree of graphics objects. The structure can be visualized like this, with each Rule constituting a parent child relationship: ...
273 views

...
372 views

### replace items in a list with items in a another list

Suppose I have a list A={x1,x2,x3}, a list B={3,4,5}, and a function f[x]=x1+x2+x3. Is there ...
493 views

### Rearranging a List

I am trying to rearrange/sort a list i.e. {{1,2},{10,140},{43,10},{1,140},{43,2}} into ...
45 views

### Arithmetic operations on columns [duplicate]

I have imported a file, data.txt, then plotted columns 2 and 3 as function of column 1 using the commands below. ...
1k views

### How to optimally solve and generalize this Conway's Game of Life puzzle

I tried solving this using mma. I am aware of this command - Cellular automata. But i don't want to use that coz then there is no challenge. So below is how i did it and my question is can this be ...
117 views

### List of lengths of runs of elements

I have a list where a few distinct numbers occur, e.g. {41, 41, 41, 1009, 41, 41, 41, 41, 41, 41, 41, 1009, 41, 41, 41} I want to extract the information of how ...
169 views

### Generating list of coordinates in $\mathbb{Z}^n$ given by set of inequalities

I am trying to generate list of coordinates that forms a subset in the integer lattice $\mathbb{Z}^n$. This set is given by set of inequalities. Right now, I am using the following: ...
264 views

### Discretizing data using quantiles in Mathematica

I am trying to discretize a long array of real numbers into a uniformly distributed integer array. To do this I am identifying the quantile where each real value sits and writing it out to the output ...
672 views

### Find positions of items in a list based on neighbours

How can I select items from a list where the selection criterion depends on the neighbouring items? For example select all indices where a change has occurred with respect to the previous element in ...
26 views

### Create a (maybe nested) list of nminimize solutions in a loop [duplicate]

I'm a total newbie in mathematica, so need some help. I understand that my question is about basics, but i couldn't find the answer in docs, google and here. Here is what i'm trying to do. ...
308 views

### How to create this list more elegantly

There is list containing some $(i,j)$ values of indices. Now i want to create a matrix of dimension n $\times$ m whose entries are 1 for the indices corresponding to the given list otherwise its zero....
249 views

### Generating an editable table that can be used as input

Say I have a number $n_{max}$. I want a command to generate a table like 1 1 2 2 3 3 4 4 ... nmax nmax where the second column is editable, and this table can be ...
853 views

### Remove list elements that contain NaN Symbol [duplicate]

I have a long list of lists ...similar to g = {{1,2,3},{4,2,7}, .....{1.2,9}}. Occasionally, g contains elements like ...
117 views

### Selective deletion of nested list elements centred around a certain value

I have a list which looks like: ...
171 views

### string to complex number

Consider the following list MyList= {-0.0000396, -0.0000187167, "0.10259130990561813-0.0677132394802944i"} Head /@ MyList (* -> {Real, Real, String} *) In ...
1k views

### Fastest way to check for List membership

I have a set of say 100 numbers {1,3,7,11,19,...3971}. All elements are previously determined. I want to check whether ...
288 views

### Question about Map and Total

Suppose I have a list and I want to generate a new list, such that $$NewList[index] = \sum_{index \neq j}^{NumOfElts} \frac {1}{ \lvert OldList[index]-OldList[j] \rvert ^2 }$$ Can I do it using ...
85 views

### Produce a 1-dimensional list of all unique matrix elements

We have some symbolic matrix m, e.g. m={{1, x, 4 x + y},{0, x y + 4x, 4x},{7 x, x, 4x + x y}} and we want to produce as output a list of all the unique elements ...
157 views

### Result of NIntegrate ploting to list

I've been working on a project where I need to make two Plots. Those plots are of the form: ...
365 views

### Partitioning time series data in sublists by their duration

I would like to do calculations on irregularly sampled time series data at intervals - for example on an hourly basis - rather than over the whole time series. The entire dataset is split up by time ...
2k views

### Shuffle product of two lists

I want to do the following: I have two lists {a_1,...a_n}, {b_1,...,b_n} and I would like to build now all shuffles out of this. This means all unions of these ...
230 views

### What is an elegant way to aggregate two cash flows

When modeling a swap contract a common operation is to sum up two cash flows producing a resulting cashflow with netted amounts in the highest granularity of the two initial cash flows. What is a ...
163 views

### Handling output that was returned unevaluated from a function

When evaluating functions, including those described in this post, how do Mathematica users handle values returned from a function that are unevaluated? For example (based on 1): ...
564 views

### Mapping functions over multiple lists

I am not sure if this is a duplicate. Spent some time looking over list-manip questions. I’d like to know the Quickest Way to achieve the following Mapping of a function over multiple lists. ...
482 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: ...
332 views

### LengthWhile until first duplication

I have the need to trim each of a large number of potentially very long lists (10^6+ elements) to the length where the last occurrence of any distinct element happens, or said another way, where the ...
111 views

### Experiment with TagSetDelayed involving Part

Reading Associating Definitions With Different Symbols, I was intrigued by this: You can think of upvalues as a way to implement certain aspects of object-oriented programming. A symbol like ...
2k views

### How to select all elements above the main diagonal of matrix?

How to select all elements above the main diagonal of matrix? I need to create a list of them.
160 views

### Elegant way to rearrange year/date table into time series/values

I often have data in the form of YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1950 -1.022 -1.146 -1.289 -1.058 -1.419 -1.36 -1.334 -1.05 -0.578 -0.395 -1.151 -1.248 1951 ...
204 views

### How can I thread lists of different sizes?

What I need is the equivalent of Maple's zip(+, A, B, 0). Sure I can get it with: ...
511 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: ...
3k views

### Semi prime numbers

The high school textbook I am using has the example of semi-prime numbers. They wanted students to find (by "perspiration") all the semi-prime numbers less than $50$ (for a question on set theory). ...
226 views

### Intersection does not take list of lists

The function Intersection takes a number of lists (sets) and finds their intersection. However, the precise input is ...
366 views

### Sorting lists element by element [duplicate]

I have a problem regarding list sorting. Let's say I have a list of lists obtained using Subsets[], of the form ...
305 views

### Specifying an array that may have an unknown number of entries [duplicate]

Say I'm running some process of unknown duration, and during the process, I need to periodically record the state of some variable. If we knew exactly how long the process took, we could simply ...
396 views

### Fast method for combining two lists

I have two lists, v1 and v2. Each element of the lists may be positive or negative. I want to create a list ...
467 views

### How to replace plus sign by comma

I want to replace plus by comma and the order of numbers in the list should be in increasing order. Example: a1 + a10 + a11 + a13 + a2 + a27 + a28 In this ...
100 views

### Evaluating the tensor product many times for a given list

I need to evaluate the tensor product 10 times in a given list( {g,e,r}) Here I have evaluated for 3 times... ...
10k 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] ...
2k views

### ListPlot doesn't shows all points [closed]

I have a table: p1 = Table[(Binomial[2000, k]*StirlingS2[1386, k]*k!)/(2000^1386), {k, 1, 1386, 1}]; I used ListPlot[p1] ...
236 views

### Counting instances where the two identical characters are at the same positions in two strings

Let $s_a$ and $s_b$ be two strings over a $q$-ary alphabet. For each character $(c_1,...c_q)$ in the alphabet, I'd like to return a pair of values $(r,k)$ where $r$ represents the count for the ...
253 views

After my evaluations I have an error: N::meprec: Internal precision limit \$MaxExtraPrecision=50. reached while evaluating ... ...
258 views

### Faster list duplicate 'limiter'

Given some list, e.g., {5, 3, 2, 3, 1, 0, 1, 3, 5, 5, 4, 5, 1, 2, 5, 2, 2, 0, 1, 4}, I need to limit the duplicates, if any, to an arbitrarily chosen number. The ...
153 views

### Choosing a position in an array with uniform random probability conditioned on it having a specific element

I have an array exArray with two types of integer elements: 1 and 2. I'd like to choose a ...