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

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14
votes
9answers
474 views

Distributing elements across a list of lists

I have two lists: u = {{1, 3}, {2, 6}, {3, 9}} v = {0, 4} and I want to obtain this list from them: ...
3
votes
2answers
105 views

Nested List Product

I want to apply Times on the elements of a list such that: ...
5
votes
1answer
170 views

How I can use Apply or Map with If?

I have list of objects: list = {{1, 1, 0.05, 0.05}, {2, 2, 0.05, 0.05}, {13, 13, 0.05, 0.05}}; list = {{x,y,Vx,Vy},{x,y,Vx,Vy},...}; And ...
1
vote
2answers
219 views

Thread over a nested list top to bottom until non-list elements are found

I have a nested list: list = {1, 2, {3, 4}, f[a], {2, h[b]}} I would like to apply a function g to all elements of the ...
5
votes
2answers
491 views

How can I get every distinct size-n combination of a list?

Let's say I have a list: {a, b, c} I would like to, for say $n=2$ get every distinct pair from that list. That is, the expected result should be, for some ...
1
vote
1answer
95 views

How do I define a function that, when given a list of parameters, plots a family of functions?

So far I've got this: draw[a_, b_] := Plot[{f[a, b[[1]], x], f[a, b[[2]], x]}, {x, 0, 5}] The function draw will be used like ...
5
votes
4answers
463 views

Join lists in a list of lists

What's the best way to join two consecutive lists in a list of lists ? For example if I have the list x = {{1}, {2}, {3}, {4}} and I want to get in x ...
2
votes
2answers
147 views

How can I replace part of list and have the replacement affect the initial list?

I have a list: list = {{1,1,0.05,0.05}, {2,2,0.05,0.05}}; and I want to do this change ...
1
vote
1answer
152 views

Random sample with gap sizes

Lets say I have 101 instances of data with multiple attributes. In particular case, one attribute has 7 unique values. I want to get ...
1
vote
2answers
258 views

How to generate patterns by a list of integers

I have a list of integers {3,4,2,2}. This list will give patterns {x_,_,y_,y_,_,_,z_,z_,w_,w_,x_} and ...
9
votes
2answers
418 views

How to represent a list as a cycle

I want to select distinct cycles (represented by List). The cycle {a, b, c, d} must be the same as {b, c, d, a} or ...
0
votes
2answers
139 views

How can I assign some part of data from one list to another list?

I don't know this is correct question or not,but I have a doubt. I have two Lists names are list1 and ...
18
votes
1answer
430 views

Using Transpose with a list as the second argument

I'm having difficulty understanding the Transpose function. I know what the transpose of a matrix is, not a problem, and I see that applying the ...
7
votes
4answers
458 views

Using MapThread on list of lists

Just a light weight question for learning. If you think this was asked before, please feel free to close it. I am trying to learn MapThread more, and wanted to use ...
8
votes
5answers
301 views

How can I find these patterns' signatures?

I think I can explain it best starting with an example. I have the following lists: ...
5
votes
3answers
165 views

All values for a function with two arguments without Outer

Given two lists $l_a = \{a_1, a_2, a_3\}$, $l_b = \{b_1, b_2, b_3, b_4\}$ and some function $f$ accepting two arguments, how can I produce a list of all values $f(a, b)$ for $a\in l_a$ and $b \in l_b$ ...
8
votes
1answer
171 views

Transformation rule on a list of non-negative integers

I am trying to create a transformation rule that takes a list of non-negative integer values of any length, finds a non-zero entry in the list, adds 1 to all preceding numbers, subtracts 1 from the ...
2
votes
1answer
467 views

If-statement does not evaluate if condition is true [duplicate]

Possible Duplicate: How to avoid returning a Null if there is no “else” condition in an If contruct I know there are other ways to solve this problem. Just because I'm curious I tried: ...
7
votes
6answers
313 views

The locations of (row-wise) minimum elements in a list

I have a list representing a 2D matrix, such as this 3 ⨉ 2 one: {{2.1, 1.01}, {0.01, 7.2}, {7.8, 2.0}} Does anyone know how to find the minimum of each row, ...
2
votes
1answer
1k views

Filtering Lists in Mathematica [duplicate]

Possible Duplicate: Select/Delete with Sublist elements? I need help in filtering long lists of x,y coordinates.Lets use the following list as an ...
2
votes
2answers
448 views

Making NIntegrate behave like a listable function

I have a function defined by $$f(t)=\int\limits_0^t g(x) dx$$ $g(x)$ is a complicated function (specifically the Mittag-Leffler function which has recently been implemented in Mathematica 9 as ...
9
votes
1answer
194 views

Unexpected result from Flatten

Consider the following three evaluations involving Flatten: Flatten[f[f[f[x, y], 1, 2], f[x, y]], Infinity, f] f[x, y, 1, ...
11
votes
8answers
447 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
4answers
301 views

Combining two lists [duplicate]

Possible Duplicate: How do I obtain an intersection of two or more list of lists conditioned on the first element of each sub-list? I would like to combine two lists. ...
6
votes
4answers
244 views

How to sum over duplicates?

I have a list of the form: {{1, 0, 1}, {2, 1, 2}, {1, 0, 3}, {2, 4, 2}, {2, 1, -1}, {1, 0 ,0}} that I would like to sort such that I calculate the sum over the ...
18
votes
7answers
522 views

How do I obtain an intersection of two or more list of lists conditioned on the first element of each sub-list?

Given two lists like list1 = {{1, 1}, {2, 4}, {3, 9}, {4, 16}}; list2 = {{2, 6}, {3, 9}, {4, 12}, {5, 15}}; I would like to produce an output like ...
9
votes
2answers
244 views

How to partition a list and leave in the last sublist which is of different length? [duplicate]

How to partition a list and leave in the last sublist which is of different length? In[75]:= Partition[{1,2,3,4,5},2] Out[75]= {{1,2},{3,4}} I want it to be ...
4
votes
6answers
207 views

Filter list with different list in it

I have a list like: {{{4, 14}, 1}, {{4, 15}, 1}, {{4, 16}, 1}, {{4, 17}, 1}, {{4, 18}, 1}, {{4, 14}, 3}, {4,15}, {{4, 16}, 2},{4,18}} Now I want to ...
3
votes
2answers
162 views

Subscript and Part: What's going on in this example?

Example I came across the following simple example from A Beginner's Guide to Mathematica, by McMahon and Topa, which I believe was written circa version 5.2. (FWIW, I'm using v9.) ...
2
votes
1answer
366 views

RowReduce: Solving for the resource vector (a, b, c) in Augmented Matrix

Here are two examples: RowReduce[{{3, 1, a}, {2, 1, b}}] evaluates to {{1, 0, a - b}, {0, 1, -2 a + 3 b}} but ...
1
vote
3answers
950 views

How to create functions of arbitrary number of variables? [duplicate]

In the following code what would be the simplest way to generalize it to say some $N_f$ number of $z$ instead of just $z_1$ and $z_2$? ...
6
votes
5answers
479 views

remove -1 values from a list

I would like to turn a list which looks like this one: {{-1, -1, -1}, {-1, 2, 3}, {-1, -1, 2}, {2, 3, 4}} into one which looks like that one: ...
0
votes
2answers
115 views

Total elements of a list that have a common first element [duplicate]

Possible Duplicate: List-operations only when restrictions are fulfilled (Part 1) I have a set of data like: ...
4
votes
1answer
281 views

Rearranging a matrix

I would like to convert a matrix which has a structure like this: {{"A", 10, "D", 1},{"B", 3, "A", 2},{"C", 7, "B", 3},{"D", 6, "C", 4}}//MatrixForm//Print; ...
3
votes
1answer
231 views

Implementing Position

As an assignment I need to re-implement Position. I've managed to do this except for one small thing, the resulting list is not in the current format. The following ...
2
votes
2answers
225 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 ...
3
votes
3answers
390 views

Combining two lists of different dimensions into a list of all combinations of points?

I have two ranges of values, one from 0 to 20 and the other from 0 to ...
7
votes
3answers
587 views

Filtering elements from a list

Suppose that I have a list {{{2, 1}, {4, 3}, {2, 4}}, {{2, 1}, {4, 3}, {3, 1}}, {{2, 1}, {2, 4}, {3, 1}}, {{4, 3}, {2, 4}, {1, 2}}} I want to make a new list ...
2
votes
2answers
186 views

Simple manipulation of imported data

I am importing 2 columns of numeric data from a data file in the way defined in this answer: ...
35
votes
8answers
2k views

Levels: how do they work?

I cannot understand how Mathematica manages levels, and so it's always a painful try-and-fail to use Flatten. Can someone please give me a very clear definition? ...
6
votes
2answers
340 views

Map a function over the columns of an M x N array

I have a $N \times M$ list of lists, or rather, a list of records and I want to map a function over its columns (e.g. find the mean temperature, age, etc.). Map ...
7
votes
4answers
216 views

Button's command is not evaluated in iteration

I wish I didn't feel like a newbie after several months, but... If I enter the following: Table[ Button[ "Number: " <> ToString @ i, Print @ i], {i, 1, 5}] ...
3
votes
1answer
352 views

Exporting/Importing a Table of complex numbers

I'm generating a long table of list of the form: PN={{1,2,1+i},{3.5,2.6,2}...},{...},... Using: Export["PN.dat", PN, "Table"] ...
8
votes
3answers
152 views

How can I use the overhang argument to Partition to avoid using PadLeft and PadRight here?

Say I have a list of values v = {v1, v2, v3, ... }. I need to partition these values to perform operations with a sliding window (think ...
2
votes
1answer
191 views

Computing closest set of points to each point in large set — running out of memory (arrays unpacking)

I have a large set of points in 3D and I'm trying to identify all the points that lie within a certain distance of each point. Then using this data store the vector between the pairs of points. I ...
5
votes
2answers
483 views

Finding the intersection of two date lists

I've got two lists that look like this ...
3
votes
1answer
330 views

Removing an ordered pair from a list of ordered pairs if the second element in the list is Less than a Value

I have a list of ordered pairs from a piezoelectric sensor sampled at 2kH. The first element is time and the second, amplitude. I'm trying to remove all ordered pairs in the list of ordered pairs when ...
5
votes
1answer
248 views

An easier and more efficient way to combine lists?

I currently have a two lists. The first list contains independent variables $x$, and the second list contains dependent variables in the form of $\{\{f[1][x]\},\{f[2][x]\},...,\{f[n][x]\}\}$. I want ...
4
votes
1answer
229 views

speed up iteration with conditionals plus optimize memory usage

Given list1 and list2 whose elements are vectors of a certain (fixed) dimension, I am interested in the behaviour of a scalar ...
4
votes
3answers
256 views

Extracting Pareto elements from a list

How can I extract the Pareto elements from a list? For example, for that list: ...