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

learn more… | top users | synonyms (3)

1
vote
1answer
85 views
1
vote
0answers
47 views

Creating a List with Lists as entries [closed]

I'm trying to create a list A which contains 8 same elements. Each of the elements look like {0, 0, 0, 0}. I was able to do it ...
2
votes
4answers
83 views

While subpartitioning the elements in list using GatherBy, can I corresponding subpartition the elements of an unrelated list?

If we have a list like the following: list1 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}; And we use GatherBy to subpartition is according to a test function ...
1
vote
2answers
45 views

Subpartitioning elements of a list based on some h[ri] == h[rj] test

If we have a list of elements: list = {r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12}; I'd like to further partition the elements into sets where, for some ...
2
votes
3answers
59 views
0
votes
1answer
69 views

How to add an extra column to a current matrix (list)? [duplicate]

a = {{-800, 1712}, {-801, 1713}, {-806, 1832}} TableForm[a] b = a[[All, 2]] - Min[a[[All, 2]]] How do I make a new matrix (list) whic looks like this ...
1
vote
2answers
48 views

Creating a list of triangle-square numbers up to n_

I have to, for a class, create a function that gives you the triangular-square numbers up to n. That said, here's the code I have: ...
0
votes
4answers
92 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 ...
3
votes
4answers
118 views

Use a categorical argument to add one layer of list structure

Consider the following nested list x = {{1,2,a}, {3,4,a}, {8,11,b}, {12,3,a}, {4,3,b}, {3,2,c}} I want to use the categorical variable ...
2
votes
2answers
88 views

Insert at specific resulting positions in multidimensional list?

I have an initial "multidimensional" list (that is, a list that is not a vector): list0 = {{1},{2,3,4},{3,4},{5}}; and I want to insert elements ...
1
vote
2answers
75 views

Insert at specific resulting positions?

I have an initial list: list0 = {1,2,3,4,5}; and I want to insert {a,x} at specific positions ...
0
votes
1answer
54 views

Plotting data from specific column

I have data like this: 1406998993.147 73 TCP_MISS/200 22284, 1406998993.158 109 TCP_MISS/200 83827, 1406998993.197 111 TCP_MISS/200 57020, If I want to plot the column 1 and ...
1
vote
1answer
97 views

Constructing new lists using Table

I tried to modify an old notebook to show a spreadsheet style output in a table. I am not getting any errors when it runs, so I think the data I am gathering and the new variables I added, ...
0
votes
1answer
48 views

Deleting list elements at a certain level

I have a large list of 3 by 3 matrices such that the dimensions of the list for an example 100 matrices would be: {100,3,3} I have written a function that locates all the matrices I do not want and ...
0
votes
1answer
53 views

Simple arithmetic operations on elements of a list [duplicate]

How can I shift the first element of a list by 148.38 and the second element by -38.45? The data ...
2
votes
1answer
61 views

second part of a list with something like BinLists

I have a list that looks like this testList = Transpose@Table[{RandomInteger[{0, 100}], RandomReal[]}, {100}]; i.e. basically two lists in one. Using BinLists ...
2
votes
4answers
175 views

How to remove hours, minutes, seconds from list

How to remove 0 that represent hours, minutes, and seconds from a date list say a ...
2
votes
1answer
33 views

In each sublist, replace the value in the right part by the value in the left part

Consider the following nested list {{a,1/x},{b,2x},{c,Sqrt[x]},{d,1-1/x}} I'd like to come up with the same list where the variable $x$ is systematically ...
4
votes
5answers
135 views

New nested list from three lists

I have three lists. x = {a,b,c,d} y = {A,B,C} z = {{1,2,3},{4,5,6},{7,8,9},{10,11,12}} and I wish to construct the following list out of these three lists ...
1
vote
1answer
93 views

Why doesn't Thread work in this case?

The following function is supposed to pick the element of the list with highest weight, i.e., with Thread [f[{{a,1},{b,2}}]] it should make the variables ...
3
votes
3answers
128 views

How to pick the maximum of a list? Improving efficiency

I need to find the element of a list, with the highest weight. Example: ...
1
vote
1answer
55 views

List Manipulation and Removing Cases

I've imported a large data set, manually removing headers in the .rtf file where it originates. However, when I import this data, I receive this output: ...
0
votes
1answer
50 views

Position of elements in a list satisfying some criteria - Understanding the syntax [closed]

From this post: if one wants to know the position of the elements of a list that satisfy some criteria, (s)he can do something like that: ...
3
votes
3answers
177 views

Trouble with Position[]

I am in trouble with Position, Although my example works as expected it throws a warning. Position[{{a,b},{a,c},{a,b}}, _?(#[[2]]==b&), {1}] During ...
0
votes
1answer
60 views

How to use Hold on a variable defined as a graph

I'm working on doing operations on different graphs and getting their probability node degree distributions using a simple algorithm. If I have many defined graphs, for example: ...
1
vote
1answer
57 views

How to make a table of successive values

I want a list, where each entry is of the form {x,y}. I want x to go from $-\pi / 2$ all the way up to $\pi/2$. I also want ...
0
votes
1answer
42 views

Elegant ways of solving this file batching task

There are a batch of data files in a folder (dir = "D:\\Documents\\datadir"), each of which consists of a list of data items, one per line. Each data item is a pair ...
1
vote
1answer
32 views

Applying MeanFilter to a large Nested Array [closed]

I have a large nested array. Let's generalize it to this: Data = {{a1,a2,},{b1,b2},{c1,c2}} I need to make a new array where ...
4
votes
4answers
162 views

Partition list into a given number of sub-lists

I'm having quite a hard time with the following. I would like to partition a list into a list of sub-lists, in such a way that the number n of sub-lists is fixed. ...
2
votes
3answers
85 views

Comparing two lists lexically

I have two lists of integers a and b of equal length, and I would like to define a>b as ...
-2
votes
1answer
57 views

Create a matrix by crossing a list

I've a list L of elements. I want to create a matrix by laying each elements of L in both rows and columns where each ...
0
votes
2answers
64 views

NSolve gives {{ x -> #}}, How do I make x = #; I need to use the x value again later

I want to use: demand = {1.92, 2.07, 2.37, 2.72, 2.87}*10^6; NSolve[SetV == demand[[1]]/(Cpf (1 - χ)), χ] I want to make a vector of solutions ...
2
votes
1answer
70 views

How can I use parts of lists with Dynamic?

I'm a newbie - what am I doing wrong? I want to use parts of lists (vectors) in calculations but Mathematica will not evaluate anything that involves parts of lists that update dynamically. Is there a ...
1
vote
2answers
297 views

What quantity is this “length” called?

tmp = {x, y, z}^{1, 2, 3} Times @@ tmp Length[%] This gives a length of 3. But I was expecting 1. What is exactly this "length" of x*y^2*z^3 called? I would ...
2
votes
4answers
114 views

List Manipulation Via Conditionals

I'm trying to convert one list to another by applying a condition on the list's elements. But I can't figure out how to do this in mathematica's language. Python example below ...
1
vote
1answer
120 views

Finding the index of (x,y) pairs in a list

I have a large list of $(x,y)$ pairs, and I want to find the index of a particular pair in order to extract some data from another array. By way of an example, ...
0
votes
1answer
56 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 ...
2
votes
1answer
65 views

Displaying a list in form of an upside down pyramid graphic

I was wondering how to display a list like this: list={{0,1,1,0},{1,0,1},{1,1},{0}} in form of an upside down pyramid, that is the first element of the list is ...
5
votes
3answers
766 views

How to build this grid with less code?

I have the diagonal and both upper and lower triangulars of a grid. ...
1
vote
1answer
157 views

Mathematica List Selection

I have a list which contains these elements : ...
2
votes
3answers
156 views

Merging two lists with possible different keys

This is very similar to my earlier question One to Many Lists Merge but somehow different. I have two lists, first column in each list represents its key. I want to merge these two lists. The only ...
4
votes
2answers
73 views

How to keep first observation and delete other observations of each group in unbalanced Panel data

I have a huge panel data. I want to create a new data keeping only first observation of each group. How can I achieve it? For illustrative purpose; ...
2
votes
3answers
162 views

Splitting a list of lists (part2)

This is a follow up from Splitting a list of lists . What would be a nice way to split the list l1 = {1,2,{a,b,c},3,{d,e}} into ...
0
votes
1answer
62 views

Duplicate values n-times [closed]

I already asked how I can take the list {1,2,3} and get {1,1,1,2,2,2,3,3,3} out of it, adding degeneracy to the problem. So far ...
0
votes
3answers
72 views

Splitting a list of lists

What would be a nice way to split the list list = {1,2,3,{a,b,c},4} into {{1,2,3,a,4},{1,2,3,b,4},{1,2,3,c,4}}
0
votes
0answers
42 views
1
vote
1answer
31 views

Generate Degeneracies in List [duplicate]

I have a list with n entries and I would like to duplicate this list p times. In my case because of the Degeneracy of my Eigenvalues. For example I have {3,2,1} and it is five-fold-degenerate so that ...
8
votes
5answers
499 views

How to subtract one list from another, treating each elements as distinct? [duplicate]

Suppose that I have a = {"A", "A", "A", "B", "B", "C"} b = {"A", "B"} How can I subtract b from ...
1
vote
6answers
104 views

Make a new list by filtering unwanted rows

I have a list like this. ...
1
vote
2answers
73 views

How do you apply an algorithm individually to an array with many graphs

I have and array with many graphs to which I want to apply an algorithm (below) to each graph in an array that contains all my graphs. ...