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

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8
votes
2answers
379 views

Aligning two lists

I have two lists, L1 and L2, each with a key and some data. Let us say the key is a person's name, a string, and the data follows. (To respond to rasher's query:) Let us also assume the lists are ...
1
vote
2answers
303 views

position of element in a list using a function

How can I find in a list l the positions of all elements satisfying a boolean function f. For example, how can I pick in ...
3
votes
6answers
340 views

How can I construct a distance table?

I have a list of city names (of arbitrary length), f.e. c = {"BAL", "NYC", "LAS", "AUS"}; and the distances between them : ...
1
vote
2answers
292 views

Find equal elements on a list

Consider the following code to produce the sequence $x_1,\ldots,x_{n+1}$ where $x_i=11\cdots1$ ($i$ digits 1). Is there an easier way to do this? ...
2
votes
1answer
110 views

How to find all possible correlations between n vectors

Given the Matrix ...
0
votes
1answer
67 views

Taking Mean for several elements of a list [duplicate]

i have the following question: Let us assume we have the following list: list={1.1,1.2,1.0,2.1,2.2,2,0,3.1,3.0,3.2} I need a function that always takes three ...
1
vote
3answers
176 views

Working with nested matrices

I have a matrix: A = {{a, b}, {c, d}} But each its element, itself, is another matrix too. ...
0
votes
1answer
162 views

How to load data into a Manipulate expression

I have data showing truncated octahedron geometry changing with time. How can I read those data into a Manipulate expression? To be specific, I want to manipulate ...
0
votes
1answer
47 views

Testing a certain function over multiple levels

I regularly want to test if a certain function, here foo, gives the expected result when mapping it over n - level - matrices. My naive approach is to write: ...
0
votes
2answers
918 views

How to pass a list as function argument?

I have the following function lFreqPhylo[a_, Q_, b_, p_] := Sum[Log[freqFunction[r[[p]][[i]], L[[p]][[i]], a, Q, b, {i, 1, nbranches[[p]]}]; The objects L, r ...
0
votes
0answers
34 views

Unexpected results from Thread [duplicate]

I've run into an issue where threading two lists with a generic function, f: Thread[f[{{1,1}, {2, 2}, {3, 3}}, {4, 5, 6}]] ...
2
votes
1answer
184 views

Is there a better way to create my rotational-symmetric (180 degrees) rectangles?

I have created a simple way to create rotational-symmetric (180 degrees) rectangles, but my stuffit function bothers me. No matter what I tried, I couldn't get it ...
1
vote
1answer
81 views

Apply function to output of previous function

I am trying to write a function that takes 3 tuples. Each tuple contains two lists which are first divided. This results in 3 lists. Then I want to take the Mean of all the columns. I can do this ...
1
vote
1answer
105 views

Matrix and string variable

There are $100$ .dat data files which contain numerical parameters. ...
1
vote
1answer
82 views

If statement and elements of an imported data

I import a data file: SetDirectory["C:\\Users\\SE7EN\\Desktop\\mathematica\\test"]; dd = Import["data.dat", "Table"] Out[2] = {{1}, {2}, {3}, {4}, {5}, {6}, {7}} ...
0
votes
1answer
60 views

Manipulating lists with constant values [duplicate]

let us assume we have some data in the following form. Table[data[[1,i,{1,2}]],{i,1,Length[data[[1]]]}] This would give all $x-y$ pairs of the first file. What I ...
1
vote
1answer
97 views

How to find the maximum values and the place of the max value in the list? [duplicate]

I have given an example to find the maximum value and its place in the list. Is it possible to find the local maximum in the sub-list of this list means local maximum in the each row of the list and ...
3
votes
2answers
132 views

Converting unevaluated lists to strings

I have a list like l = {2 - 3, 12 - 4, Times, aab} I want to end up with {"2-3", "12-4", "Times", "aab"} I have tried ...
8
votes
1answer
150 views

Strange behavior of BinCounts

Bug introduced in 8.0 and fixed in 10.0.0 Just try this example: ...
2
votes
2answers
163 views

Building adjacency matrix from set data

I have two sets: games and players. Players pick their games. As such I will have data say g1={p1,p3,p5},g2={p2,p4},g3={p2,p3,p5}. My interest though is to build the connections among players because ...
4
votes
1answer
183 views

Selectively converting numerical strings to expressions

I have a list of strings representing different types of data ...
2
votes
1answer
55 views

Grouping Nested Lists Based on Differing Values of Single Element

I've a list of lists representing k-rows of truth table having n elements each in a nested list consider ...
2
votes
1answer
74 views

Generating list of functions from list of expressions

I know how to create a function from concrete expression like Function[{x, y}, x^2 + y^2] But what if I have a list of expressions list1 and I know the set of ...
1
vote
2answers
91 views

Manipulate which creates and deletes Manipulators dynamically

I want to plot a function in a Manipulate in which the number of terms varies and a Manipulator for the coefficient of each term ...
0
votes
1answer
138 views

Select positive value from a vector

I am wondering how to pick out the positive Omega value from soln, and make these positive values into a row vector. I know how ...
0
votes
1answer
82 views

How to discriminate Weatherdata latitude and longitude from a more detailed list

From this list of weather data how can I discriminate only latitude longitude for each station? For example from the following sample I would need only the coordinates: "50136","","Aoluguya|Mohe, ...
1
vote
2answers
118 views

How to drop the identical rows and columns of a matrix?

I'm currently trying to find a way to eliminate from a square matrix of generic dimension the duplicate (up to sign) rows and columns, obtaining a smaller dimensional matrix. I searched around here ...
0
votes
1answer
101 views

How do you add options to a function that is being mapped?

Simple example: Normally: ListPlot[list, Joined->True] If I want to map ListPlot how do I keep the ...
1
vote
2answers
222 views

From a list of (x,y) pairs, generate a new list of (x,ymean) pairs, where ymean is the average of all y's with the same x in the original list [duplicate]

This seems like the sort of thing where Mathematica can give a very simple solution. I have a list of points {x,y}: ...
0
votes
2answers
91 views

Merging two lists by prepending elements

Being a newcomer to Mathematica, I have the following question. Given x = Range@9~Partition~3; and y = {a, b, c}; I want ...
2
votes
2answers
95 views

How can I get a certain kind of iteration?

Can I get this type of do-loop in Mathematica? Do[Print[j," ",k," ",l], {j,k,l, {a, b,z}, { c, d,y} }] I want this to work so that, in the first iteration, ...
0
votes
1answer
180 views

ListDensityPlot with discrete bins [duplicate]

We consider a table of the form data = Flatten[Table[{i,j,f[i,j]},{i,1,ni},{j,1,nj}],1] The function f[i_,j_] has been made ...
2
votes
0answers
102 views

ParallelTable and expensive functions

I would like to build up a 2D-Table using ParallelTable as follows ...
0
votes
1answer
68 views

How to take single item out of List? [duplicate]

I often get Lists that contain a single item, like {name} or {{2,3,4}}. Is there a function ...
2
votes
2answers
116 views

Extracting “records” from a matrix

From a rank 3 matrix like ...
4
votes
2answers
639 views

What is the Mathematica way of joining two tables?

Is there a special Mathematica way of joining tables of data together, so that I would get similar functionality as if I was running a database with sql? For example, I have one particular table ...
2
votes
2answers
107 views

Componentwise Addition of TemporalData

I'm a little confused with the TemporalData structure in Mathematica, in the sense that it doesn't seem to behave like a list. What I'd like to do is plot the sum ...
2
votes
1answer
151 views

Find positions where two matrices differ

I have two matrices A and B of identical dimensions. What's the simplest (shortest) way to find the indices of differing ...
0
votes
1answer
76 views

Drop last element of parts of a list [duplicate]

just a simple question for now I guess: I have a list: list={{1, 2, 1}, {1, 10, 1}} I simply want to Drop the last element of the two entries of the list, that ...
1
vote
3answers
166 views

How do I select only those lists whose elements are all above a certain number?

I'm essentially doing coin flips, using RandomReal to populate a bunch of lists, each with 8 elements. I then want to select only those lists for which all elements are greater than a certain number, ...
1
vote
1answer
186 views

How to define a list that contains all primes less than x?

how can I define my own list in which I have all primes less than x?
0
votes
1answer
40 views

save all inputs as list [duplicate]

I received three results of calculations: {k->0.190729} {k->0.197575} {k->0.249319} Could you help me write the results in the following form: ...
3
votes
3answers
306 views

How to insert elements of a list into list of lists?

I have two lists. E.g. ...
0
votes
2answers
130 views

Having problems with ListPlot and a PaddedForm wrapper

I defined a function f[x_] = x^3 2 x. Then I had to construct a table showing vertically, the values of f corresponding to x on ...
10
votes
2answers
567 views

Faster “stuttering” accumulate?

Given some list of arbitrary precision numbers, e.g. (actual lists are 1M+ elements long): test={0, 2, 2, 47839283, 2, 0, 0, 2, 0, 1, 2, 0} I need to accumulate ...
2
votes
2answers
280 views

Generating complete lists of polynomials

I would like to generate a list of all $3$-variable Laurent polynomials with non-negative integer coefficients using a looping construct so that I can, one-by-one, check them for specific ...
2
votes
2answers
466 views

List density plot for non-uniform data

I am trying to make a density plot to show the data that can found here. I tried with GNUplot previously. The result of GNUplot density plot for a rectangular set of data. I am able to do this only ...
1
vote
1answer
133 views

What is wrong with setting one list to another within function? [duplicate]

I have built a function which carries out a set of operations given two parameters. The function looks as follows: ...
1
vote
1answer
564 views

How to find non zero elements of a list containing zeros and symbols

I have a list, obtained after differentiating a list of expressions, which contains zeros and symbols, say: A = {x1^2, x2^2, x3^2, x4^2} D[A,x3] results in the ...