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

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1answer
122 views

A problem with set values

The following code is just an example to clearly explain my problem. Assume that : ...
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1answer
54 views

how to use Manipulate changing the values of a List?

How can I "change" the values in the list h={2,4,6} using Manipulate? (Next line was edited after hte first Alexi´s comment) I WANT to choose real values in h[[1]], h[[3]] , h[[3]] between 0 and 8. ...
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1answer
79 views

Running function - updating list - run function etc

I am making a larger program, so I would prefer to give a short example of my problem: ...
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2answers
161 views

Summarizing SQL Tables

data = Table[SQLSelect[conn, "All", {"col1", "col2"}, SQLColumn["col1"] == n && SQLColumn["col2"] == o], {n, 1, 8}, {o, 21, 30}]; This results in ...
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3answers
99 views

Function to naming columns

I often import files from excel or csv files and they come in a format like this: ...
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1answer
169 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 ...
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1answer
65 views

Extracting second value of each sublist [duplicate]

How can one get the second value of every array inside the outside array? I have the following data data = {{10, 20}, {30, 40}, {50, 60}}; I want to extract ...
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1answer
58 views

Optimise CPU-intensive list combining function

I have a list of numbers list1 from which I want to create another list (list2) consisting of only those numbers that are equal ...
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1answer
73 views

How to use ImageMultiply[] over a list of strings?

I'm trying to do the following: ...
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3answers
131 views

string to complex number

Consider the following list MyList= {-0.0000396, -0.0000187167, "0.10259130990561813-0.0677132394802944i"} Head /@ MyList (* -> {Real, Real, String} *) In ...
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2answers
130 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): ...
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2answers
154 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 ...
0
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2answers
267 views

Replace all elements of a list

I have a set that looks like: s = {{1, 2, 3} -> 9, {4, 1, 9} -> 9, {3, 7, 3} -> 1}; Now, I want to replace each element of the set by the lhs of "...
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1answer
211 views

Passing lists to functions in a manner that works like pass-by-reference in other languages?

Is it possible to use a list as a variable, i.e., to pass it by reference to a function? In particular, I have a two-dimensional array and a function to get one element specified by its position: ...
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2answers
463 views

Finding max value of each column of 4x4 Array

I have the following array in both MatrixForm and List form ...
0
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1answer
265 views

How can I build a GraphicsGrid of fixed size that rearranges the empty plots?

OK, let's make one final attempt; they say the third time is the lucky one! Following @rm-rf 's suggestions, I will try to be as clear as I can. My Mathematica code reads and plots simultaneously ...
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2answers
136 views

Create a Matrix out of two matrices

I have two matrices A = {{a1,a2},{b1,b2}} and B = {{x1,x2},{y1,y2}}. I would like to create out of these matrices a new matrix ...
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1answer
276 views

ListVectorPlot3D

I try to plot a 3D Vector plot. All Vectors start at (0,0,0) and point in directions given in spherical coordinates: ...
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1answer
92 views

Making a list from equations

I want to make a list (efficiently) which is the set of lattice solutions of the following equations (depends on $k$): $x_0\geq 0$ and $x_i\in [0,4k]$ for $i=1,\ldots,4$ satisfies $x_0+x_3\leq k+3$, ...
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1answer
163 views

Problem with ListContourPlot feeding data format and WeatherData

With following code I am trying to show the mean wind speed patterns for a few geographic locations. ...
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1answer
936 views

How to calculate the area of a listplot [duplicate]

I need to calculate the area enclosed in a two-dimensional listplot and following an answer to a similar question I tried this way: ...
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2answers
679 views

Finding max, min, and closest root of two dimensional data

I have some data that is two dimensional (traditional (x, y) format) as so: var = {{x1, y1}, {x2, y2}, {x3, y3}} I would like to search through that large list ...
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2answers
157 views

Convert *.txt file

I would like to Import and Convert a *.txt file which looks like: https://docs.google.com/file/d/0Bw-308nJcF01Yl92RURCLUg4VzQ/edit?usp=sharing and turn it into a Matrix which I can use to make ...
0
votes
1answer
560 views

Keeping axes fixed in an Animate of a 3D graphic

I am using the following code to animate a 20 3D ListPointPlots: ...
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1answer
73 views

How to get a number, but not a list, of the dimension of your array?

I need to use the dimension of a certain array, to use it as a bounder in a loop afterwards. The problem is that I get a list, when write : ...
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1answer
165 views

Discrete 3D plots of median ratios of two 2D matrices of lists of values

Lets say I have 2 2D arrays where each cell contains a list of values: Example: ...
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1answer
35 views

How to loop in a nested Association?

Considering we have an Association: ...
0
votes
1answer
59 views

How can I use nonlinear model fit with multiple variables? [closed]

I have a data set with four entries. the first three entries correspond to variables in the fit x,y, & z. The fourth entry corresponds to the function value. I am trying to fit this data to a rate ...
0
votes
1answer
54 views

How to import data from a .mat or a .txt file and manipulate dimensions

I'm new to Mathematica (I know very, very little - so I apologize if anything I say is absolutely wrong) - but I'm trying to upload a file from matlab and arrange it in matrix form. I have a .mat ...
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1answer
49 views

Replace element of matrix based on rule which invloves other element of same matrix

I am trying to replace 1s row of matrix d iteratively from right by multiplying last element in 1st row with (1-int*dt) to generate 2nd last element. The replacement continues till I reach the 1st ...
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2answers
63 views

Writing a function with variable arguments [duplicate]

I want to write a function which takes multiple arguments varying from 1 to n, where each argument is a triplet. sublistProduct[{$a_1,b_1,c_1$},{$a_2,b_2,c_2$},...] = { $\Pi_{i=1}^{i=n}a_i ...
0
votes
1answer
70 views

Unexpected results from output with NumberForm and ScientificForm

I wrote this little function to help me export tables with formatted numbers to files: (By the way, if you have suggestions on how to make it more efficient and compact, it would be great) ...
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votes
1answer
28 views

How to combine two or more groups while selecting form the unbalanced panel data if the number of obs is less than a scalar in certain groups

I have an unbalanced panel data. I want to calculate group statistics for each group. However, if ith group has less than K obs, then I want to combine ith and (i+1)th groups to calculate group ...
0
votes
1answer
37 views

operating lists [closed]

I have 2 lists 25 items, as I do so that data entering this formula ...
0
votes
4answers
66 views

Delete data were y = “NS” in a list with elements {x, y} [duplicate]

I have a list of data {x, y}and not all of them have actual values. They show as {x, "NS"} or ...
0
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2answers
76 views

Block anti-diagonalize a square matrix?

In Mathematica there is a very convenient function called JordanDecomposition[]. It takes a square matrix A as an argument and ...
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1answer
38 views

Writing a math formula to order results in a certain way [closed]

I am not very well educated in math and I have a math puzzle that I'm trying to solve. I have the following list and each object has 3 numbers. The first 2 numbers are better when they are as high as ...
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votes
1answer
51 views

Length of Union Incorrect?

I am having a problem with the Union of sets not giving me the correct Length. ...
0
votes
2answers
80 views

Convert Range to List of Strings

I need to generate the result given by ...
0
votes
2answers
42 views

Selecting elements from a list [duplicate]

I have the following array of numbers: a = {{0, 2, 5}, {3, 5, 1}, {4, 0, 5}, {8, 3, 4}, {0, 8, 6}}; then I make a list of the first row with ...
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votes
2answers
50 views

Table results within loops

I have the following code. ...
0
votes
1answer
55 views

Compute the evolution of several quanties from a data file

This question is somehow a part II of this: Part I. Here comes a small data sample as a minimal working example: ...
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votes
1answer
61 views

Correcting a gap in ListPlot

This is a small sample of my data ...
0
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1answer
66 views

ListPicker delayed output

I'm trying to make a wrapper for ListPicker that delays updating the list unless Ctrl or Shift is released. The aim is to allow nested ...
0
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1answer
94 views

for loop and list

I'm new to Mathematica. I want to built a function like that; ...
0
votes
4answers
104 views

how can one select elements from a list that are satisfied a criteria which need to compare with other elements in the list?

For example: I want to select elements from a list {1,4,3,2,5} that are bigger than its previous element. {4,5} satisfies the criteria: 4 is greater than 1 and 5 is greater than 2(Ignore the first ...
0
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1answer
70 views

Why `Delete` does not work?

I'm trying random thing in Mathematica just for learning and I can't solve this problem. I want to use the Detele function to delete some elements in a list but ...
0
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1answer
107 views

Recursive functions taking list arguments

I wish to create a function that takes lists (e.g. {plus,plus,minus,0,minus,plus}) and uses the input list to calculate a corresponding value using a set of ...
0
votes
2answers
93 views

Finding an idiomatic way to express a system of linear equations

I have an $n$ x $n$ matrix $T$, where $t_{ij}$ is the element at the $i\,$th row and $j\,$th column, and unknowns $x_i$, $1\leq i \leq n$, where $$x_{n} = 1$$ $$x_{n-1} = 0$$ $$x_i = \sum_{1\leq j ...
0
votes
3answers
107 views

Manipulate list in function

I have some problems with lists and functions. Basically I just want to cut all entries from the right side, which contain 2. ({2,1,2} should become {2,1}) ...