# Tagged Questions

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

196 views

### How to speed up a For-loop [closed]

My code is the following: ...
78 views

### Who can explain the strange behavior of command “Last”

Situation I use Last to extract the last element of an expression. Let poly=a+b*c+Log[a]+z. Problem When Using ...
144 views

### List of functions to list of parameters

I am working in a Dataset and I need to create a function for a ChartStyle option of a ...
80 views

### apply binary operation to all adjacent pairs

Is there a built-in or more efficient approach than using Partition to apply a binary operation to adjacent pairs of elements? That is, is it reasonable to be ...
153 views

### Reverse DeleteDuplicates using Information from Tally

I have a list of values, e.g., {1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 4, 4, 4, 5}. I delete the duplicates with ...
133 views

### Seeking a way to generate sequential partitions of a list using built in or Combinatorica functions [duplicate]

This code generates all "sequential partitions" of a list: ...
59 views

### Problem with MissingDataMethod [closed]

Given v = {2, 1, Missing[], 5, 7, 4}; I use EventSeries to replace the missing value with its predecessor ...
137 views

### Inserting an indexed string into the 1st position of each pair in a list of pairs

How do I insert "Z" and then a number going from 1 to end (without space) in a list? I have the following list: Input: ...
55 views

### Bin data from an imported excel file by adding 5 elemets of y axis each [closed]

So i imported a file from excel and viewed it as a grid. but now i need to add groups of 5 elements from the y axis and plot them against every fifth entry from the x axis. Thanks Edit: Sorry about ...
118 views

### Trouble adding elements to array [closed]

I need to generate array and export it to file. For n = 1 , second element must be 0 For n = 2.. 819, second element must be 1 For n = 820.. 1637, second element must be -1 For n = 1638.. 16384, ...
69 views

### Filter two lists of 2D coordinates such that only those that have a nearby neighbour in the other list are collected

I have two sets of coordinates: GreenPairs.xls RedPairs.xls I'm only interested in the coordinates that have a very close (overlapping in the plot below) different coloured neighbour. The ...
330 views

### DeleteCases In Mathematica

I want to eliminate all the sub lists containing exactly two positive numbers? My list is ...
57 views

### FindLinearRecurrence is not working for numerical complex number sometimes?

First FindLinearRecurrence definitely support complex number list, see ...
83 views

### TakeWhile for nested list

I have a nested list of time and position for multiple particles over multiple time steps. I want to cut all the time steps off (for each particle) after which the $z$ coordinate goes above a certain ...
229 views

### Avoiding copies when modifying lists

Consider the following approach to modifying a list: ...
39 views

### Manipulating a symbol via its name [duplicate]

I'm trying to change the entries of a list. The problem here is that I only know the symbolname of the list for example name="x" , where x is defined as ...
457 views

### How to sort list of mixed types of elements with each type a specified canonical order?

For example, here is a list {{1, "u"}, {6, "d"}, {3, "u"}, {4, "d"}, {2, "u"}, {5, "u"}, {3, "d"}, {1, "d"}, {4, "u"}, {2, "d"}, {5, "d"}, {6, "u"}} The ...
215 views

### Random Partitions

I want to write a function RandomPartition to partition a vector of length n into p partitions of varying (random) lengths. For example with ...
558 views

### How do you concatenate matrices? And how do you make block matrices?

This is pretty trivial to do in Matlab, but I have not seen a function for it in Mathematica. Here is how you can do it with Join and ...
34 views

### Producing a list [closed]

Table[x, {i, 5}] In mathematica 9 this results in {x,x,x,x,x}, but in v10 it's {1,1,1,1,1} ...
90 views

### Efficiently traversing a list

Suppose I have a large list of algebraic expressions, sorted by their equivalent numerical value (under a certain set of assumptions). Some of these expressions are identical, but commands like ...
213 views

### Association Subtotals with Lists as Keys

I have the following Association: ...
225 views

### How to make a Slash header in Grid?

Here is an example, ...
195 views

### DeleteStopwords in other languages?

I saw that in new version of Mathematica there is an interesting function: DeleteStopwords that deletes stopwords from a list of words, but this function is only ...
176 views

### How to print of all ternary number of 100 digits?

For example, to print all ternary number of 3 digits I would do something like this Do[Do[Do[Print[i, j, k], {k, 0, 2}], {j, 0, 2}], {i, 0, 2}] to return 000, ...
160 views

### Coloring spiral structures

In a previous question Original post @Julian S. proposed a method for coloring spiral structures. However this method works well only if the two spirals do not merge together. For example, for these ...
361 views

### A simple list question

If I have list1={x^a, x^b, x^c} and list2={1,2,3}, how do I substitute one into the other to get ...
156 views

### Opposite of Differences

I want to add the successive the elements of a list. As we know the operator "Differences" performs the difference of the successive elements of a list. Is there a function which performs the opposite ...
170 views

### How to fit multiple Gaussian peaks to data [duplicate]

How would I fit this data with Gaussian Peaks? I have tried various codes but none have even worked. Note: If I do Log[data], the peaks are more visible (I have tried the method from here but it got ...
118 views

### Fitting multiple peaks

I am using the code found here to fit multiple peaks of a large dataset which I don't know anything about. This was the only code I could find on the internet to do such a thing. So this is my attempt ...
36 views

### Difficulty with LevelSpec. Product of empty set should be 1

I have a matrix newm = {{{}, {}, {-p}}, {{d}, {e}, {p}}, {{g}, {h}, {i}}}; MatrixForm[newm}; whose elements are lists. I would like to multiply the elements of ...
21 views

### Remove background from multipeak data [duplicate]

Let's say I have a a very large list of data in the format {{n,f[n]}} so something like {{1,600},{2,700},{3,1100}...} and if this data is plotted, then it will look like a sum of Gaussian functions+a ...
252 views

### Removing background from peak function

Let's say I have a a very large list of data in the format {{n,f[n]}} so something like {{1,600},{2,700},{3,1100}...} and if this data is plotted, then it will look like a sum of Gaussian functions+a ...
202 views

### Timing problem with ReplaceRepeated

I have the following data: ...
375 views

### Exception with GatherBy: gathering complex conjugates

I want to gather the complex-conjugates that are in a list, but with an exception: only if the imaginary part isn't zero. For example: ...
374 views

### get position index for all element in a list

For example mat={{a,b},{c,a,a}} How to write a function posindex that posindex[mat] will ...
69 views

### Multiply equations in lists

list = {x + 1, x - 3, {x - i, x + i}} The last two elements should be multiplied. Desired output is: {x + 1, x - 3, x^2 + 1} ...
59 views

### Multiply elements within a list [closed]

How do I multiply elements within a list? list = {{1}, {2, 3}, {4, 5, 6}, {7}, {8,9}} Desired output: {1, 6, 120, 7, 72}
114 views

### How to take every second element [duplicate]

If I have {1,2,3,4,5,6}, how do I take all the second elements into a new list? So I want a list like {2,4,6}.
128 views

### Grouping the first two elements in a list of ordered triples

I have a long list of the form ...
126 views

### Efficiently generating plots from lists of differing lengths

I guess this is more of an informatic question. A quite complicated function of mine generates me a list of valid points, depending on a parameter, like this: ...
90 views

### Overlap between lists of sublists with different dimensions

I have two lists of sublists. The sublists in the first list contain three elements while the points in the second list contain four e.g.: ...
110 views

### Collecting Data in table

I wrote a program (with help of the stackexchange) that is supposed to run in a loop. Each time the program runs, it exports a small data. Is it possible to generate a table where each run adds the ...
239 views

### Referencing previous elements in the same List

I'm looking for a way to reference an element within a List to get another element in the same parent List. I can't really see ...
151 views

### How to find period of a discrete sequence?

For example, {1,2,3,4,5,6,7,8} has period 1, the base is {1} {1,2,4,5,7,8,10,11} has period 3, the base is {1,2} I ...
130 views

### Why does my MapThread expression fail in this case?

This morning, I opened one of my previous notebooks and evaluated it. Surprisingly, the code produced an error. This took me a whole four hours to find the problem and it is with ...
153 views

### Allocate amount A according to the distribution of amount B

I have a cost that varies by category and date. I also have the counts of each item type within each category and date. I want to distribute the cost to each of the item types. I'm trying to use <...
99 views

### How to transform data in character form into a sensible form?

I have a data output from a device in a form of a string. I need to transform it into such a form that I can work with it, such as plot columns with respect to one another and such. After a apply <...