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

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2
votes
3answers
230 views

Adding elements in the sublists

How can I add the elements in the sublists? For example, if I have the list which is m={{1,3},{2,3},{4,1}} then, the output that I want is ...
3
votes
2answers
270 views

Deleting a row or column of an adjacency matrix while maintaining the associated label

I am currently working with a weighted adjacency matrix for a directed graph, and it contains several 0 columns and rows. With the unaltered matrix, I am able to monitor the relations between vertices ...
4
votes
1answer
262 views

Use single ListPlot for multiple sets of data (on separate graphs)

This is the code I have working for a single set of data. Is there a way I can structure this to have multiple sets of data? ...
3
votes
2answers
844 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. ...
13
votes
9answers
576 views

Thread over list in different levels

I have these two lists, both with the same length in the first dimension: ...
3
votes
1answer
173 views

How to efficiently take complement of two big lists?

I have a giant list l1 and some smaller lists l21, l21, ..., ...
1
vote
3answers
184 views

Logical operations on a list [duplicate]

Possible Duplicate: Applying And to lists of Booleans I have two lists filled with logicals: ...
11
votes
4answers
383 views

What's fastest way of defining 10^5 down values?

I want to define isGood[___] = False; isGood[#] = True & /@ list where list is a list of several million integers. ...
5
votes
3answers
161 views

Comparing Unequal Lists of Surnames to Establish Over or Under-Representation

I've been using Mathematica to explore historical records. I have two long lists (one is 69k, the second 17k) of unequal length. They are like so (FWIW, the first list is the first 40 entries from the ...
4
votes
3answers
393 views

Generate a Combination of letters by a number

I'm trying to write a function f. example: ...
5
votes
3answers
3k views

Local max/min of Mathematica data sets

Is there a way in Mathematica to find the local maxima of a set of points? Suppose you have ...
5
votes
3answers
833 views

Transform a Sum into a List

I want to turn a sum like this sum =a-b+c+d Into a List like this: sumToList[sum]={a,-b,c,d} How can I achieve this?
4
votes
2answers
250 views

How can I use Max[] in a function that is passed a list not find the max of the list

For most functions in Mathematica, passing them a list will call the function on each element of the list. For example: ...
0
votes
3answers
1k views

How to make all values positive?

So I have a list of data that contain both positive and negative values, and I am wondering what I have to do in order to make all the numbers positive.
3
votes
3answers
354 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 ...
0
votes
2answers
105 views

How to evaluate the sum using values from the data being input

I have a problem in evaluating a sum using values from data I input. Suppose I have data = {1, 3, 5, 6, 8} If I want to evaluate the sum of my data (1+3+5+6+8), I ...
2
votes
1answer
145 views

Specifying form in MemberQ

This seems like a very simple question, the answer to which should be obvious to me. So I won't be offended if this question is closed. But I'm having trouble figuring out the answer. I would ...
1
vote
1answer
497 views

Using 'Reduce' to solve a set of inequalities, specified by a list

I have a two lists $LHS$ and $RHS$, both of size $n$. I want to solve a system of inequalities of the form: $$LHS[1] \leq RHS[1]$$ $$LHS[2] \leq RHS[2]$$ $$LHS[3] \leq RHS[3]$$ $$\vdots$$ ...
2
votes
1answer
127 views

Generating continuous products or sum

This is kind of a continuation of this question. I want to automate these 2 steps on Mathematica once I give an integer $N$. generate a list of variables $\{a_i\}_{i=1}^{i=N}$ then for some ...
12
votes
4answers
2k views

Reshape vectors exactly like in MATLAB

This gives a 64×1 column vector in Mathematica: ...
6
votes
4answers
1k views

Alternatives to While Loops?

I am using Mathematica to run a probabilistic simulation. Essentially, I have a list of members of a population (they only have one, numerical, attribute, so it's just implemented as a list of ...
2
votes
2answers
438 views

Mathematica: summing over n abstract indices

This probably has a one line answer, but I'm totally stuck. I have two tensors, i.e. two objects that depend on NN abstract indices which i've labelled ...
12
votes
4answers
496 views

Calculate proportion of values for dates

At work, we were discussing when is it the best time to change to winter tires for bikes and/or cars. Using WeatherData[] and ...
14
votes
6answers
462 views

Splitting a list by specifying section headers

I have a list of strings called mylist: mylist = {"[a]", "a", "a", "[b]", "b", "b", "[ c ]", "c", "c"}; I would like to split ...
6
votes
1answer
419 views

Find all permutations with reversals / cyclic permutations removed

I have a list of all non-cyclic permutations of n labels. How can I get rid of all elements which are redundant in the sense that they are the inverse of another one. For instance if n=4, the ...
2
votes
3answers
344 views

Maximum tuple value

Is there a simple way to make a maximum tuple value (similar to python)? For example, in python max([ (1,2), (1,3), (3,1), (4,0) ]) returns ...
15
votes
3answers
2k 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. ...
12
votes
3answers
546 views

Simpler way to fill date gaps with zero values

One basic problem when working with data like sales and dates is the case where you dont't have sales in all days, so you have to fill it to take information as average or to make a plot. See this toy ...
2
votes
5answers
161 views

Test First row of matrix

What is a good way to test the first row of a Matrix to check if one of the values equal a value. For instance, In this example, I want to get vector in the second row that has the bigger value in the ...
2
votes
1answer
138 views

Intersection of conditions

If I have a list of conditions: {cond1,cond2,cond3} and I want to use an If[] statement to test the intersection of these ...
3
votes
2answers
553 views

Dynamically remove element from list based on test

Suppose I have a list l = {a, b, c, d, e, f....} I would like to remove one of each pair {x,y} if some function ...
3
votes
1answer
227 views

How to partition MatrixPlot graphics?

Is there an easy approach - hopefully built-in - to partitioning MatrixPlot graphics into rows or columns (or both) of graphics sharing the same underlying options? ...
4
votes
2answers
520 views

Loop and do operations on Matrix, then graph the results

I'm trying to do some operations to a matrix in a loop, and then I want to graph the results. The results are pair of numbers. Can I store the results of each iteration on "something" and the use ...
1
vote
2answers
103 views

NSum generates a warning message when getting the sum of a list

I know what I'm doing can be done with Total: a = Range@3; Total@a And if I simply choose ...
9
votes
1answer
219 views

Ranking Function Allowing for Ties

I have a list that I need to be able to assign ranks to individual elements in, giving it a number related to its position if the list were to be sorted, allowing for ties. For example, ...
7
votes
3answers
437 views

How to Gather a list with some elements considered unique

I have a list of the form: list={{0,...},{1,...},{1,...},{0,...},{3,...},{3,...},{0,...},{0,...},{5,...},{5,...},{5,...},{0,...},{5,...},{0,...},...} So when we ...
5
votes
1answer
638 views

Splitting a list using SplitBy, by comparing adjacent elements [duplicate]

Suppose that I have the following list called mylist: mylist = {80.2, 80.3, 80.4, 327.6, 327.7, 327.8}; I would like to split ...
2
votes
4answers
319 views

plot data differences

I have the following data: ...
6
votes
2answers
318 views

removing elements that are contained in other elements

For example, I have a list of lists: l = {{a,b,c},{a,b,d},{d,e},{d},{a},{a,b},{f}}; And I want to remove all the lists that are contained in other lists: ...
2
votes
1answer
212 views

How to get the results of Tally split into two separate lists

This is a kind of a followup to my previous question. I am starting with a long list of plane coordinates, like this one: ...
18
votes
5answers
645 views

Map-Thread-Through-Apply a list of functions onto a list of (lists of) values

I have a list of functions: fns = {f, g, h} and a list of triples: ...
6
votes
3answers
268 views

Importing and manipulating strings - time data

I have a list of time durations, which are strings of the form: "hh:mm:ss". Here's a sample for you to play with: ...
6
votes
1answer
263 views

How to compile Map and MapAt

I have a long list (say, million of elements, like this one: {{{1.0, 2.0}, 3}, {{4.0, 5.0}, 6},...} I would like to compile a function ...
8
votes
1answer
286 views

Elementwise, compilable min function

I am trying to implement efficiently a transfer-matrix like algorithm. On each iteration, I have two vectors $x=\{x_1,\dots,x_n\}$, $y=\{y_1,\dots,y_n\}$ with real numbers and I need to compute the ...
2
votes
2answers
170 views

Constraining a random function

This question is a follow-up from here. I have a function that generates a list of correlations between some random variables: ...
4
votes
1answer
227 views

Timing differences between multiple executions of identical code

I have a list of pairs of numbers and I'd like to change the sign of the second element in each pair i.e. $(a,b)\rightarrow (a,-b)$. I'm sure there are many ...
3
votes
2answers
485 views

hexList[[1]] returns a list of decimal numbers

Sorry for not being clear about this question earlier. I appreciate the answers I got, but the edits I made should make the question more understandable. I have been working with hex in ...
1
vote
2answers
272 views

Combining lists with common elements efficiently [duplicate]

Possible Duplicate: Computing the equivalence classes of the symmetric transitive closure of a relation I am required to process sets consisting of 2-element subsets of integers by ...