Questions on the manipulation of List objects in Mathematica, and the functions used for these manipulations.
3
votes
1answer
76 views
0
votes
0answers
63 views
How can I solve this system of functional equations?
I would like to use Mathematica to find maps a, b, c, d, e, f such that
...
2
votes
0answers
89 views
Derivatives of list elements
Could someone explain the odd behavior of the Derivative function when drawing arguments from lists? We have,
...
2
votes
2answers
104 views
Importing several huge files with headers & footers
having here several files in ASCII format
http://ge.tt/91rv0Jf/v/0
I want to import, while removing headers and footers and then join the several lists.
...
0
votes
1answer
74 views
Using a loop to make a new list by taking elements from multiple lists [closed]
I have defined three lists and I need to be able to take elements from them periodically and put them in a new list. I know I need to use some form of a loop but I am at a loss. Any suggestions?
5
votes
4answers
233 views
Any rule of thumb for converting a simple mathematical expression into a pure function?
By simple mathematical expression I mean one with a few functions and few variables copied into MMA in a mechanical way from a math book.
For example this one, giving the distance between two points ...
0
votes
1answer
78 views
Dynamic List Building and Exporting [closed]
My ultimate goal is to have a text file that contains the following information in the following format exported to a text file:
...
1
vote
1answer
59 views
Splitting list of sums into a sum of lists
I want to split a list of sums into a sum of lists For example, I'd like to turn
{{x + y + z}, {x}, {y}, {z}}
into
...
5
votes
1answer
106 views
Is there an equivalent of “shiftdim” of MATLAB?
Recently I'm spending my time implementing some computer vision algorithms, which usually handle a large amount of data.
The problem I'm facing now is that I have to reform my video data to pass it ...
5
votes
3answers
239 views
Replace “,” in a list with “.”
I have a list which consists of numbers which use comma (,) instead of dot (.) as their decimal point. I would like to replace the commas, but only those commas which are followed by more than five ...
18
votes
6answers
812 views
1
vote
1answer
41 views
Partial row reduction of a matrix
I have an $m\times n$ matrix (presumably of full rank) with $m>n$, and I would like to row reduce it, but leave the last column unreduced; that is, I want to get output on the form
$\pmatrix{ 1 ...
10
votes
4answers
343 views
Finding Local Minima / Maxima in Noisy Data
I'm trying to find local minima / maxima in noisy data, consisting of data values taken at certain time intervals. Ideally, the function should take a pair of lists (one containing time values and one ...
0
votes
2answers
94 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 ...
1
vote
3answers
93 views
How can I create a new tables out of a table and plot it
I have the following problem. I have a table, call it m, which is labelled by 3 indices (say i,j,k), each of them running from 1 up to 100.
I would like to be able to construct a new table which would ...
12
votes
6answers
769 views
Find continuous sequences inside a list
I have a list which is something like this:
{3,4,5,6,7,10,11,12,15,16,17,19,20,21,22,23,24,42,43,44,45,46}
What I'd like to to is get the intervals which are in ...
27
votes
4answers
560 views
Filtering beat-to-beat heart rate data
From an experiment, I have a dataset of beat-to-beat heart rate data: a list of the time between each heart beat in [ms].
The data is measured using an infrared optic sensor at the finger tip. The ...
5
votes
1answer
106 views
nested use of Apply/Map/MapThread in pure functions
1. My main question
I have a function with two argument slots. I wan't to apply this function to 2 lists with different length's. I thought in this solution:
...
3
votes
3answers
192 views
How to sum over a List
list = {11.5575, 11.397, 5.52734, 4.0878, 2.54815, 1.86652, 2.55028,
2.14952, 1.6242, 1.34117}
I have a list of numbers. How do I make a function that creates a ...
1
vote
1answer
52 views
ReplacePart inside For loop
I am trying to replace the last column of the following expression (mat) by doing
...
2
votes
1answer
72 views
Plot several lines with different starting points on the x-axis
First of all, I would like to apologize in advance if I don't use the correct terms or if I express myself unclear but I just started to work with Mathematica.
I'm simulating electricity prices and ...
0
votes
1answer
73 views
Keeping axes fixed in an Animate of a 3D graphic
I am using the following code to animate a 20 3D ListPointPlots:
...
11
votes
3answers
760 views
Data interpolation and ListContourPlot
I am fairly new to Mathematica and I have two quick questions on using it for a Hydrology and Hydrogeology class. One is about data interpolation and interpolating without any data defined in an area. ...
5
votes
2answers
143 views
How can I find if the number of subsets for a list is very large?
I'm trying to find the following;
Subsets[Range[2, 2300], {4}]
but my computer gave the following error:
...
12
votes
1answer
128 views
How can I make threading more flexible?
Threading automatically with Listable functions requires the argument expressions to have the same length (or for one of them to be atomic). For nested lists the ...
9
votes
2answers
215 views
How to extract and compute on the diagonal entities of a sparse matrix very fast?
As could be seen in the following code:
...
1
vote
3answers
101 views
Logical AND operation over several comparisons
Let x and y be arrays defined as Array[x, m], Array[y,n] respectively.
How to generate the following function of $x$ and $y$ for variable $k$
...
0
votes
0answers
55 views
How to combine file data chronologically via reading numbers in a filename and put it in one list?
Say I have a bunch of files with nearly same filename, eg. data_timestep1, data_timestep2, ...
The data itself in one file is ({x1, y1, z1, absolute field value 1}, {x2, y2, z2, absolute field value ...
6
votes
2answers
325 views
Elegant way to handle columns operations
Inspired by this question from @sjdh and by my recurrent use of columns operations in database sets, I was looking for one way to make columns operations more symetric, so I can handle with matrix and ...
2
votes
1answer
99 views
Including two ListLinePlots in a 3D graphic
I have two lists of data which I am plotting on two ListLinePlots. I would like to have these two plots appear perpendicular to each other on a 3D graphic. I have ...
12
votes
2answers
432 views
How do I split up a curve into segments of equal length?
I have a curve that is defined as f[x] and what I'm attempting to do is to divide the curve into equal straight lengths for a number of segments of my choosing that I've defined as nSeg.
I've created ...
17
votes
7answers
693 views
Selectively Mapping over elements in a List
I am using the following code to easily generate a row of images of all eight planets of our Solar System:
...
4
votes
2answers
275 views
List reversion inspired by Python
In python, if you wish to reverse a list, here is the trick:
range(10)[::-1] => [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
Note: ...
-4
votes
4answers
94 views
Extracting the integers from a list
I have a list where the elements are Reals and Integers. How can I extract the Integer? For example, if I have {1, 2, 3.4, 9.9}, how can I get ...
11
votes
8answers
379 views
Any built-in function to generate successive sublists from a list?
Given
lst = {a, b, c, d}
I'd like to generate
{{a}, {a, b}, {a, b, c}, {a, b, c, d}}
but using built-in functions only, ...
1
vote
3answers
136 views
Summation over 3 lists
I have three lists. As an example,
a = {10, 5, 6, 8, 7};
b = {4, 8, 9, 7, 9};
c = {7, 5, 12, 4, 1};
I want to get
$$x(i)=\sum ...
0
votes
0answers
26 views
Error in extracting a column [duplicate]
I imported excel data to Mathematica using this command.
kuruzD = Import[
"C:\\Users\\TMH\\Documents\\Problem Set 4\\kuruzData.xlsx"][[1]] //TableForm
I want to ...
0
votes
3answers
85 views
How to find intersection of multiple lists excluding empty ones?
I have lists like
list1={1, 1, 2, 3}; list2={3, 1, 4}; list3={};
I want to find the intersection of all list. I tried the following way, but it's not working.
...
1
vote
2answers
149 views
What ways are there to convert an Integer to a list of digits?
How can I convert an Integer to list of numbers? For example:
781049 ==> {7, 8, 1, 0, 4, 9}
What are the possible ways of ...
1
vote
1answer
171 views
2
votes
5answers
110 views
Creating ordered triplets from an Excel sheet
I have an Excel sheet of the form:
" " a b c
1 R S T
2 U V W
3 X Y Z
Where every entry is a number (except the blank quotes, ...
0
votes
1answer
69 views
DataRange problem in a ListLinePlot within a Manipulate
I'm trying to create a simulation of a set of lists with Manipulate[] and ListLinePlot[]. However, as my simulation starts with ...
0
votes
0answers
38 views
DeleteCases and Inequalities [duplicate]
I would like to remove cases from a list according to an inequality rule - e.g. remove all values less than x. I can do the following but this seems very clumsy:
...
2
votes
2answers
80 views
How to prevent errors in Manipulate with ListPlot when a result is an empty list?
I am trying to plot two lists, where one is the reference list, and the other is only used to select and highlight the first list. Basically, I want to use the selection list ...
7
votes
2answers
229 views
Finding all points of period n in an iterated map
I'm trying to implement an algorithm of Jenkinson and Pollicott to calculate the Hausdorff dimension of a Julia set for the map $f_c : z\mapsto z^2 + c$. It's described on page 40 of their paper, ...
4
votes
5answers
197 views
Removing zero values from ordered pairs
I have some processed data, which are basically a collection of ordered pairs in the form:
{{x1, y1}, {x2, y2}, ..., {xn, yn}}
Ordered pairs which have either a ...
2
votes
2answers
139 views
Position function not always retuning an answer even with no apparent problems
I'm having some problems with Position.
Sometimes it will give an empty list instead of the actual position of the element I am looking for when that element is ...
13
votes
6answers
327 views
Matrix Rotation
If I have a 2 D matrix of any size say
$\left(
\begin{array}{ccc}
72 & 32 & 64 \\
18 & 8 & 16 \\
63 & 28 & 56 \\
\end{array}
\right)$
$\left(
\begin{array}{cc}
72 & ...
1
vote
2answers
91 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 ...
3
votes
2answers
110 views
