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

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4
votes
1answer
149 views

Searching for closest entry in a table

I have a large table of triplets whose structure is: list=Table[{a,b, RandomReal[]}, {a,1,100}, {b,1,100}] I would like to search through the list by looking ...
1
vote
1answer
137 views

Need help scoring randomly generated SEC football rankings

So my task is to score all the possible rankings of the 14 SEC football teams and find the best one, using who won in head-to-head games as the sole criterion (so not factoring in strength of schedule ...
0
votes
1answer
186 views

Generate encoding from nested list

Taking reference of Huffman code algorithm, ...
3
votes
4answers
372 views

How to apply a function of several arguments to a list?

I have a list of triplets: list = {{1, 3, 5}, {4, 5, 1}, {4, 9, 2}} How can I apply a function f to the last element of each triplet when f the last and ...
4
votes
2answers
220 views

How to set up and minimize a large system of equations to resolve the individual components

I am trying to set up a system of 400*N equations to deconvolute spectral data for four different compounds. I monitored 400 different wavelengths in N solvents (3 solvents in this case). In order ...
3
votes
2answers
247 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
1answer
110 views

Recursion when randomizing elements in a list

I want to randomize certain elements of a list; Since the code list = {a, b, c, d, e, f, g}; list[[{1, 3, 5}]] = RandomSample@list[[{1, 3, 5}]]; list works fine, ...
1
vote
0answers
338 views

Convolve two sets of (x,y) data sets

I have two sets of data in the form a={{.1,2},{.2,3},{.3,4},{.5,6}} b={{0,8},{.1,4},{.2,7},{.3,1},{.5,10},{.6,3}} Both data sets have even spacing, although ...
8
votes
3answers
402 views

Deleting quasi-duplicates from large list efficiently

I have the need to remove "duplicates" from large (>10K members) lists, where a "duplicate" is either a verbatim duplication, or the element's second entry exists as a first entry for some "earlier" ...
2
votes
3answers
155 views

Plotting lists, exact color values

I read some descriptions of similar problems but I cannot make them work in my example, I don't know why. I have list of 3 dim values to plot: x, ...
2
votes
2answers
131 views

Merge two Matrices without Duplicates

I have two matrices, for example: data1 = {{"c1", "c2", "c3"}, {2, 5, 3}, {54, 2, 3}, {11, 2, 10}, {3, 5, 7}}; and ...
1
vote
0answers
106 views

New list generated from the sum of elements taken from two lists

I have been using mathematica for a while, but I have problem wrapping my head around list manipulation functions. I would appreciate any suggestions. Here is what I want to do. ListV is a list of ...
-1
votes
1answer
136 views

Plotting the results of a system of equations

I believe this is a question of more list manipulation than plotting, but I hope you could help me. I solve numerically a system of equations of 3 variables, take only real solutions where one of the ...
2
votes
3answers
169 views

Join matrix based on conditions

Given the following matrix: ...
3
votes
4answers
252 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 ...
8
votes
5answers
370 views

Manipulating a sublist based on position

I have a huge list with huge sublists of the form list={{a,b,c,d},{e,f,g,h},{i,j,k,l}} I am looking for a way to manipulate these sublists based on the positions ...
1
vote
0answers
37 views

How do I define a tensor from another tensor with summations? [duplicate]

Let's say we have a rank 2 tensor $g_{ij}$. This is basically a list with a Depth of 2. Now I'd like to calculate another tensor ...
3
votes
5answers
443 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 ...
5
votes
3answers
207 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}] ...
7
votes
1answer
343 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: ...
2
votes
3answers
232 views
4
votes
1answer
268 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 ...
10
votes
2answers
468 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 ...
0
votes
0answers
44 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. ...
5
votes
2answers
854 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 ...
0
votes
2answers
101 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 ...
1
vote
2answers
160 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: ...
1
vote
2answers
203 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 ...
9
votes
4answers
617 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 ...
0
votes
0answers
24 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. ...
5
votes
2answers
304 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 ...
2
votes
2answers
191 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 ...
0
votes
1answer
510 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 ...
1
vote
3answers
115 views
0
votes
3answers
140 views

string to complex number

Consider the following list MyList= {-0.0000396, -0.0000187167, "0.10259130990561813-0.0677132394802944i"} Head /@ MyList (* -> {Real, Real, String} *) In ...
14
votes
3answers
797 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 ...
5
votes
3answers
282 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 ...
0
votes
1answer
76 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 ...
1
vote
2answers
142 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: ...
1
vote
1answer
294 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 ...
14
votes
6answers
1k 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 ...
2
votes
1answer
209 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 ...
0
votes
2answers
134 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): ...
1
vote
2answers
417 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. ...
3
votes
2answers
329 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: ...
7
votes
5answers
327 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 ...
1
vote
1answer
98 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 ...
8
votes
7answers
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.
2
votes
2answers
137 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 ...
2
votes
2answers
180 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: ...