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

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0
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1answer
69 views

Help with DeleteCases [closed]

Trying to delete small elements from a list with copy = DeleteCases[copy, {y_} /; y <= 1500.0 ] but it does not work.
1
vote
1answer
74 views

Matrix and string variable

There are $100$ .dat data files which contain numerical parameters. ...
0
votes
1answer
53 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
59 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}} ...
1
vote
2answers
103 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 ...
16
votes
3answers
3k views

K-means clustering

In MATLAB, there is a command kmeans() that divides an array into $k$ clusters and calculates the centroid of each cluster. Is there any command in Mathematica to ...
1
vote
1answer
73 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
0answers
78 views

Why does Part behave like it transposes lists? [closed]

From the documentation of Part: Part[expr,i,j,...] is equivalent to expr[[i]][[j]]... ...
17
votes
4answers
292 views

Setting parts of a list

Suppose I have list a = Range[10] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} in which I want to set some elements to be a list ...
2
votes
2answers
121 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 ...
3
votes
2answers
101 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 ...
1
vote
1answer
47 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 ...
4
votes
1answer
134 views

Selectively converting numerical strings to expressions

I have a list of strings representing different types of data ...
1
vote
2answers
73 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 ...
10
votes
3answers
506 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 ...
0
votes
1answer
45 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 ...
0
votes
1answer
64 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, ...
12
votes
7answers
832 views

How to Set parts of indexed lists?

I would like to assign a list to an indexed variable and then change it using Part and Set like this: ...
0
votes
1answer
92 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
121 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
72 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 ...
1
vote
1answer
70 views

How can I get a certain kind of iteration? [closed]

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, ...
4
votes
2answers
170 views

Correlation with missing data

I have two lists, age and score, that I want to find correlation on for 50 people. For some people, the score is blank. Example data: ...
0
votes
1answer
75 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 ...
4
votes
1answer
213 views

Apply color function to matrix plot

I want to apply the following color rules to a large table of numbers. I have extracted a part of the table to use as an example. I would like to assign 5 different colors to 5 different ranges of ...
2
votes
0answers
64 views

ParallelTable and expensive functions

I would like to build up a 2D-Table using ParallelTable as follows ...
2
votes
2answers
105 views
0
votes
1answer
57 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 ...
4
votes
2answers
251 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 ...
1
vote
1answer
51 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 ...
0
votes
1answer
73 views
1
vote
1answer
112 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?
2
votes
1answer
134 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
52 views

Extract Position where value is unequal to 0 [closed]

When I use Position[somelist,0] I get the position where values are 0. But what would be the command to get the positions which are unequal to 0 ...
0
votes
1answer
44 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 ...
0
votes
2answers
122 views

ListPlot with spherical coordinates with data from file [closed]

I have a file that is a table of values for r, $\theta$ and f(r,$\theta$) with r and $\theta$ being spherical coordinates, $\phi$ being 0 the whole time. The data thus looks like ...
1
vote
3answers
135 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, ...
2
votes
3answers
186 views

Speeding up a simple simulation with random extractions

I wonder if anybody can help, I need a hand with a simple simulation I am writing with Mathematica (I am using version 8). Basically it creates a list (called l) with numbers from 1 to n and a random ...
1
vote
2answers
478 views

Research positions of lists of varying size

I'm new to the site and I am French, so I ask your indulgence for my future mistakes in English. I would like to optimise the following code : ...
3
votes
3answers
223 views
0
votes
1answer
37 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: ...
0
votes
1answer
150 views

How to format the data in a table to have only numbers

This question is in continuation of my earlier query, how to store output of a function in a table for future use. I am able to store the output of my function in a table, however the table consists ...
0
votes
0answers
70 views

Improving a function that filters each table from a list of tables

I have written the following function which can take in a list of tables as an arguement, and then filters each one. The function I wrote is below, and the commands I combined are listed below the ...
0
votes
2answers
97 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
540 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
147 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
176 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
79 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
110 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 ...
0
votes
3answers
90 views

How to get the indices of values in a list which are NOT an specific integer?

I got a real array A, where Dimensions[A] == {5000, 5000, 5}. Some of the values in A are ...