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

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1
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1answer
133 views

Ways to access lists inside lists

I have gone through some reference material but I am not getting really good links that will help me grow understanding of ...
2
votes
2answers
132 views

Replacing all values in a table > $T$ [duplicate]

I want to generate a table of Euclidean distances from the points in a list to a given point, e.g.: ...
4
votes
2answers
150 views

How can I replace the general element of a geometric series with the sum of the series?

Consider the list mylist = {b(a/bc t)^r, a/b(b t)^r, a (c/d t)^r, ...} where a, b, c, t, etc., are real numbers between 0 and 1. I want to sum each term in the ...
-4
votes
5answers
277 views

List manipulation by indices of indexed variable names [closed]

Each of my indexed variable represents a curve, and each variable has four indices with practical meaning, e.g. first index indicates whether this curve is a bedding interface(1) or fault (2).; second ...
1
vote
1answer
167 views

merge daily and hourly time series data

I have two lists of time series data. One of the lists is daily and is formatted like this; ...
3
votes
2answers
113 views

Multiplying expressions within a list of pure functions

Let's say I have a list of pure functions that are nice algebraic expressions: say l = {(#1 - 1)&, (#1^2 + #1)&, (#1^3 - 1)&} What's an easy way to ...
2
votes
2answers
130 views

Extracting counts of contiguous zeros and ones from a binary array

I'm a novice with Mathematica, but you guys have been very helpful to me in the past. I have a binary array [100, J repetitions] consisting of zeroes and ones. I'd like to extract a histogram of the ...
0
votes
0answers
123 views

Manipulate inside a function definition

I am writing a notebook where I have to configure several curves (using locators in manipulates), to not repeat code I would like to write a function that wraps a manipulate and returning the ...
0
votes
3answers
87 views

How can I generate a generalized product to two lists in a special way? [duplicate]

Let's say I have two lists, and I'd like to generate a "cartesian product" from these two. Specifically Inputs: A = {{{1}}, {{2}}, {{1}, {2}}}; B = {8, 9}; ...
0
votes
0answers
67 views

Importing specific columns of a .txt file [duplicate]

I have text delimited file, with data in four columns. How to use ReadList to extract only the first and the fourth column.
0
votes
2answers
123 views

How to put a list of values on a single axis and add custom labels

I have a table in the following format: Apple 2 Pear 3 Banana 5 Orange 6.5 .... I would like to put the values on a single horizontal axis and add corresponding descriptive labels (apple, pear, ...
7
votes
9answers
385 views

Convert list of lists to cumulative join

I have this: list[1]={1,2,3}; list[2]={7,8,9}; list[3]={15,20,22}; I want this: ...
0
votes
2answers
187 views

Building a new table by repeating elements from another table

I have a small problem that I cannot solve. I have two tables, one with three elements: a = {0, L/c, 2L/c}; and the other with 9 elements, all 0: ...
1
vote
2answers
143 views

Removing pairs that meet a given criterion from a list [duplicate]

Let $(x_{min},x_{max})$ and $(y_{min},y_{max})$ represent lowerbound and upperbound acceptable values for some coordinate $c_i$. Setting $x_{min} = y_{min} = 1$ & $x_{max} = y_{max} = 9$, how ...
-1
votes
2answers
95 views

Extracting only complete records from two data sets and combining them

I have two data sets: ...
3
votes
1answer
126 views

Combining the items with common available dates from two lists [duplicate]

I have two lists of data including dates such as data1 = {{{yy, mm, dd}, a}, ...} data2 = {{{yy, mm, dd}, A}, ...} There are some missing dates from each list, ...
1
vote
1answer
154 views

Bincounting a list

I'm a Mathematica novice here. I'm trying to execute the following code to add random 1's into a zero matrix, repeat this many times, and then bin/histogram the number of nearest neighbor 1s. Can ...
18
votes
7answers
914 views

Elegant and fast way to join all string sequences

I want to do what title says: {"a","b",1,2,3,4,"a",2,2,2,"edg","?"} => {"ab",1,2,3,4,"a",2,2,2,"edg?"} in the most elegant way. For example one replacement rule for ...
10
votes
3answers
281 views

Looking for an elegant way to construct this tensor-product-ish list

I would like to make the following matrix: ...
0
votes
1answer
69 views

How does PolarPlot render a nested list of functions?

I am getting unexpected plots from PolarPlot when I provide a list of functions that I generate using Table. I suspect the ...
4
votes
2answers
211 views

Removing not-a-number entries from an array of numbers

I have a list of {x, y, z} coordinates from a wavefront sensor I'm working with. However, not all of the imported points have actual values, but they still get ...
2
votes
1answer
120 views

list manipulation [duplicate]

I have a list like the following: {{1, 3}, {2, 5}, {3, 6}, {2, 4}} I want the final list to be like that : ...
3
votes
2answers
96 views

Non-canonical re-ordering of nested lists

I have some data in the form: ...
2
votes
2answers
111 views

Select rows of matrix that are higher than a given row

Imagine I have the following matrix: X={{0,0,0},{1,0,1},{1,1,1},{1,2,1},{3,3,3}}. I want to select the sublists that are greater or equal than this list ...
2
votes
1answer
127 views

How can I randomize the elements of a list?

Is there a straightforward way to go from an ordered list like: ord = {a, b, c, d, e, f, g, h} to a disordered list like: ...
3
votes
1answer
109 views

Assigning Sequence to Part of a SparseArray (bug?)

Part ▪ You can make an assignment like t[[spec]]=value to modify any part or sequence of parts in an expression. ▪ If ...
2
votes
2answers
204 views

Find local maximum in 3D list

I have a set of data of the kind {{$x_i$, $y_i$, $z_i$}, ...} at randomly chosen points $x_i, y_i$. The $z_i$ are supposed to be a smooth function of the $x_i$ and $y_i$. Unfortunately they turn out ...
2
votes
0answers
140 views

Strange behavior of undocumented RawArray and ArrayObject expressions

I discovered several strange results and inconsistencies while trying to understand what undocumented RawArray and ArrayObject ...
1
vote
1answer
224 views

Measuring the area of non analytical regions in a plot [duplicate]

As the title says, I want to measure the area of different closed regions in a plot. Let me be more specific by giving a characteristic example. In the following figure, we observe that inside the ...
2
votes
1answer
136 views

Coarse-graining and/or sorting of a list of arbitrary triades {x,y,z} in the (x,y) plane [duplicate]

In general my question is related to an approach to make an interpolation of a data which is not on a regular mesh. Another aspect of this question has already been discussed after my question ...
12
votes
6answers
495 views

Sort+Union on a list

Probably this is too trivial question for this forum but for some reason I am not getting it on my Mathematica 7 so far. I have a list ...
9
votes
6answers
392 views

Performing Computations on Sets

I would like to find a permutation of $\quad S=\{\frac{1}{10}, \frac{1}{2}, \frac{4}{7}, \frac{3}{5}, \frac{2}{3} \}\quad$ that maximizes the sum of theses elements raised to unique powers: ...
0
votes
0answers
106 views

How can I revise my program to avoid “No more memory available”? [duplicate]

I have a program for calculating a type of list. ...
0
votes
1answer
108 views

Forming product of function of prime factors

Given a list of numbers each containing 2 prime factors, I wish to make a list of the products of the logs of each factor. For example, given L = {4,6,9}, I would like to form P = ...
1
vote
1answer
205 views

Find elements of a list which are empty

Sorry for the most basic of questions. How would I find the positions of a list of elements which are empty, for example I have the list ...
1
vote
1answer
237 views

Simpson's rule with ListConvolve or ListCorrelate

I have a function that's represented as a long list of values that I want to integrate. I can do it procedurally with Simpson's rule. ListConvolve generally runs faster then procedural code, so i ...
3
votes
1answer
152 views

Little problem with Through

list = Partition[Range[20], 5, 5, 1, {}] {{1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}, {11, 12, 13, 14, 15}, {16, 17, 18, 19, 20}} ...
1
vote
1answer
138 views

Equating two lists, element by element

Say you have two lists: listA = {a, b, c} listB = {d, e, f} How would you produce a listC that equates each of the two's ...
1
vote
0answers
85 views

Optimized subset algorithm implementation

I was reading a paper from Mathematica Journal.It mentions a code for calculating subsets. ...
5
votes
3answers
400 views

How do I find the intersection of a closed 3D curve given by numerical data with a specified plane?

I have a list of 3D data points which form a closed curve. My own data can't be easily generated analytically, but the qualitative behaviour is well represented by a parametric curve families such as ...
1
vote
0answers
134 views

Why doesn't ParallelMap improve the performance of FoldList?

This question arose during my analysis of the following problem: filling gaps. (The code used here is Simon Woods's work.) FoldList seems to not cooperate with ...
2
votes
4answers
193 views

How to improve the quality of the ListPlot output

I need to plot massive data stored in external ASCII files. Below is the Mathematica code I use for this job: ...
12
votes
10answers
597 views

How can I generate a nested array like this one?

Well, this is how the array looks like: I came up with this code: n = 10; Nest[ArrayPad[#, 1, 1 - #[[1, 1]]] &, {{1}}, n] /. {1 -> "*"} Any better ...
2
votes
2answers
125 views

Modify all the second elements of every pair in a list of pairs

I have a list in the form {{a, 1}, {b, 2}, {c, 3}}. Let's say I want to operate a transformation on all the second elements of each sublist, but this transformation is a function of them all ...
15
votes
6answers
542 views

How do I replace a missing value in a column with the value immediately above throughout a table?

I have a large table (7000 rows × 17 columns) of terse textual data. In many of the columns, empty entries have been replaced with "." as a marker. Working from the top of the columns downward, I want ...
14
votes
7answers
564 views

A function that accepts a pair or a list of pairs

Probably a duplicate, but it's not easy to search on "lists". I have a function that accepts a list of lists, say {{a1, b1}, {a2, b2}, {a3, b3}} and performs some ...
8
votes
5answers
250 views

Wrapping a function in count

I am working through the Programming Paradigms via Mathematica (A First Course) and am attempting to answer the following: Use recursion to count how many times the argument can have its square ...
20
votes
15answers
967 views

How do I extract the middle element(s) of a given list?

How do I extract the middle element(s) of a given list? Here is some code that works, but seems a little too long: ...
5
votes
1answer
165 views

What is the fastest way to maintain a large set of expressions?

In my algorithm I need to maintain a set (an unordered list of distinct elements) of expressions supporting two operations: Test an expression for membership in the set Adding a new expression to ...
2
votes
1answer
66 views

Adjust the results of evaluating Table so it can be used as a argument to Point

I have a list generated by Table as below. ...