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

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3
votes
3answers
695 views

Sum of Multinomial Coefficients

Basically, I want to write a function to compute the following sum $f(m,L):=\sum_{0\leq k_1,\cdots, k_n\leq m} \binom{m}{k_1,k_2,\cdots k_n}$ and $\mathrm{supp}(k)=L \subseteq \left \{ 1,...,n \right ...
3
votes
3answers
215 views

Plot sublists as different colors

I have one big list with many sublists inside. All sublists consist of three numbers. For example: ...
3
votes
3answers
245 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 $k$: ...
3
votes
2answers
1k views

For loop with steps other than 1

I would like to do a For loop with a jump 2*Pi instead of 1. For[j = 0, j <= nmax, (incr = 2 Pi), ...] Actually what I want to do is ...
3
votes
2answers
79 views

Output matrix with common elements

Given lists of lists like a and b, I want to obtain an output like c. a = {{2, 1, 0}, {1, 2, 1}}; b = {{2, 2, 0}, { 2, 2, 1}}; c = {{2, 0, 0}, {0, 2, 1}} If ...
3
votes
3answers
188 views

How to Update 2D List based on a binary array

I have 3 lists: numbers = {{1, 2}, {3, 4}, {5, 6}}; toUpdate = {{1, 0}, {0, 0}, {1, 1}}; newValues = {{10, 20}, {30, 40}, {50,60}}; I have to update the list ...
3
votes
3answers
164 views

Finding the first position in a list that is over a certain value

Let's say I have the following list: L = {2,4,6,8,10} How can I get Mathematica to find the index position of the first value in the list that is over 4 (6 in ...
3
votes
5answers
338 views

How to extract strings from the list with an additional condition on previous elements?

There are a long list of strings $s$ and two lists of substrings $s1$ and $s2$. I want to take all elements of $s$ which contain a substring from $s2$ and such that before it on no more than $n$ ...
3
votes
4answers
118 views

How to combine the elements of two lists using a user-specified function

I have two lists of integers. From these lists I want to produce a list where each element is a fraction derived from a corresponding pair of elements in the original lists, the smaller integer of the ...
3
votes
3answers
153 views

Cases or Select for catching elements in a list?

I have A list that contains sublists like that: ...
3
votes
2answers
433 views

Why does a certain CSV file import properly into LibreOffice but not into Mathematica 10.0?

I'm working on a project involving data manipulation and it involves working with CSV files. I know that the files are properly formatted as when I import them into LibreOffice, all of the columns ...
3
votes
2answers
258 views

Weird behavior when changing parts of matrix

I have this matrix: mat = {{1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}, {11, 12, 13, 14, 15}, {16, 17, 18, 19, 20}, {21, 22, 23, 24, 25}}; and here are its second row ...
3
votes
3answers
149 views

Lists - pairing up

I have two (fairly large) lists of equal length & would like to pair them up. eg - from: a = {{0, 1}, {0, 2}, {0, 3}}; b = {{1, 2}, {1, 3}, {1, 4}}; I would ...
3
votes
2answers
853 views

Adding and subtracting from elements in a list

I'm trying to solve an aparently simple problem. Given a list of length n, {a1,b1,c1,d1...} I want to perform two simple ...
3
votes
5answers
584 views

How to combine some elements of a list?

In order to simplify my expression, I face a list manipulation problem. For example, given the input list ...
3
votes
2answers
113 views

Nested List Product

I want to apply Times on the elements of a list such that: ...
3
votes
3answers
470 views

How to pull scalars out of a function that should act on lists?

Suppose I have A = a vecA B = b vecB where a and b are supposed to be arbitrary scalars ...
3
votes
3answers
317 views

Combining heads of lists so that you can create a nested list from two sublists

I have a list such as list = {1,4,3,4,6,3,1,2,3,4 ... } and a range, say, range = Range[20000]. I want to obtain the following ...
3
votes
3answers
149 views

Move element inside a list

I need to change the position of a single element in a list. Example: I start with: {a,b,c,d,e,f} I want to move the a before ...
3
votes
3answers
83 views

Identifying locations of entries in an array

If I’ve got a big array displayed in Mathematica, is there a way for me to select a particular location on the screen and have Mathematica tell me “You’ve selected the entry in row 137 and column 92” ...
3
votes
3answers
197 views

Pare down list recursively

What is the best way to pare down a list whereby the $n$th number is removed from the list recursively? This ...
3
votes
2answers
108 views

Matrix of given size with unspecified elements

I want to generate a Matrix of given size whose elements are not specified I can use Array[a, {3, 2}] to get ...
3
votes
5answers
527 views

Randomly selecting and reinserting a subset of elements in a list

This question is similar to my other question: How do I randomly select 'k' positions in a list and shuffle their respective elements without effecting the other elements? Imagine first a ...
3
votes
3answers
213 views

Finding a better way to define a matrix

I first defined a 171x171 matrix containing only zeros and then replaced 18 specific rows with nonzero entries. The other $153$ rows will be average of $2$ of the existing $18$ rows. Rows $2$ ...
3
votes
2answers
243 views

List manipulation after importing txt-file

I have some problems converting data which I imported from a txt-file into proper Mathematica expressions. After importing my data looks like ...
3
votes
4answers
245 views

Finding the location of the last day of the month in a list of dates

My question differs from earlier questions about getting the eom dates from a list; I want to get the position of those dates so I can get the corresponding values from other lists. My problem seems ...
3
votes
2answers
323 views

Replacing values above a threshold with 1 [duplicate]

I have a list with some values and I want to replace a value which is greater than 1 with 1 otherwise keep the value. In this case 10562: ...
3
votes
3answers
190 views

Picking certain pairs according to a condition [duplicate]

I'm a Mathematica beginner and can't find out a solution to my problem. I have a list of pairs of numbers, for example something like this, but much longer: list={{2., 3.}, {3., 2.}, {5., 4.}, {4., ...
3
votes
3answers
189 views

Count items in a list that occur before a date

I have a list of dates that happen throughout 2013. I wish to construct a graph showing a cumulative total of elements that happen before that date. I have a working algorithm, but it seems too slow ...
3
votes
2answers
170 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.) ...
3
votes
2answers
1k views

Trying to generate a list of data to plot a graph with error bars. Need help creating the looping function

This is the sets of data I want to put into a form which will allow me to plot error bars from the min and max data. ...
3
votes
4answers
178 views

Building intervals

I'm facing the right know the problem of building intervals to an arbitrary number. The special thing is that the first and the last intervals should have fixed length, while the "middle" ones should ...
3
votes
3answers
280 views

How can the lowest non-zero value in a nested list be found and its position in the sublist returned?

In the example code below we have a list of triples that produce one or more sublists with at least one zero value. How can the positions of the lowest non zero value in each sublist be returned ...
3
votes
5answers
133 views

How to filter list of list of rules on certain condition?

For example, Solve[] returns all solutions as a list of list of rules. And mine looks something like this: ...
3
votes
3answers
196 views
3
votes
2answers
451 views

Convert a list of hexadecimal numbers to decimal

I know that to change a single number from hexadecimal representation to decimal, you can use: base^^digits. However, if you have a list of numbers, Mathematica ...
3
votes
3answers
159 views

List manipulation: Dropping first or last row or column of a matrix

How do I drop the first/last row or first/last column from a matrix? The general case is answered here but I am new to Mathematica and it the arbitrary case is unnecessarily complex. Suppose I am ...
3
votes
2answers
114 views

How to define a list of symbols as a list of functions?

I have a list in Mathematica for example P={1+t,1+t+t^2,1+t+t^3}; My question is, how I can define each element of this list be a function of ...
3
votes
3answers
185 views

Breaking up combined data into several smaller data sets

I have one combined data with first number as the x-value and the remaining as different y-axis values (y1,y2,y3...). How do I break this combined list, data= (x,y1,y2,y3...) into smaller lists, such ...
3
votes
3answers
200 views

Zero-order interpolation not going fully around

Connected to this question, I want to do a zero-order interpolation of a bunch of datapoints which is periodic. The code I use is as follows: ...
3
votes
3answers
247 views

How can I extract multiple spans from a list?

I know in Mathematica, I can do A = Range[100]; B = A[[50 ;; 60]] B will then contain the 50th through 60th elements of A. Now, what if I wanted B to take 10th ...
3
votes
4answers
243 views

Delete Missing data from coordinate sets

I have a list of pairs of coordinates, where some are missing. ...
3
votes
1answer
198 views

How can I find the average of the ordinate of an indefinite number of lists of points?

Suppose that I have three lists: list1 = {{0, 1}, {0.1, 10}, {0.2, 100}}; list2 = {{0, 1}, {0.1, 10}, {0.2, 100}}; list3 = {{0, 2}, {0.1, 20}, {0.2, 200}}; In ...
3
votes
2answers
252 views

Using the elements of a subset in a Do loop

I would like to use the elements of Subsets in a Do loop. I have: ...
3
votes
3answers
123 views

Max function used with nested lists

I have a list as follows lis1={{{1,5,6},{4,7,8}},{{1,2,2},{5,6,7}}} and would like to calculate the max value of each nested list in order to get following ...
3
votes
2answers
108 views

Generating Z^*_n

I'm using Mathematica to illustrate basic number theory concepts in a graduate cryptography class. To generate elements of the multiplicative group of integers modulo $n$, i.e. $\mathbb{Z}^*_n$, I can ...
3
votes
4answers
120 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 ...
3
votes
2answers
107 views

Sublists of Random Permutations

What is an efficient way to create a list of (psudo)randomly chosen permutations? I'm trying to create a list like below: ...
3
votes
5answers
151 views

Creating a new list by dropping sub elements of the original list

Suppose I have a nested listed as follows, {{{1,2},{3,4,5},{2,3}},{{2,3,4},{5,4,1},{1,4,3}},{{3,4,5},{3,4,5}}} Where the elements are, ...
3
votes
2answers
314 views

Finding positions of multiple elements in lists

I realise that Position[{2, 4, 8, 16, 32, 64}, 4] will return {{2}} I would like to do something like this: ...