# list-manipulation's questions - English 1answer

4.851 list-manipulation questions.

### 1 Efficient way to make updates in a big List

I would like to know is there is a way to do this: ...

### 3 Efficient way to detect peak value changes in a list

3 answers, 122 views list-manipulation peak-detection
ListPlot[list, Joined -> True, PlotRange -> Full]I would like a simple method to get the positions within the list where the values deviate a lot from ...

### 12 Element-wise test on List elements

6 answers, 1.035 views list-manipulation map operators
This question could sound pretty silly but I can't find a way to apply element -wise tests to a list. For example if I digit ...

### 1 Randomly merge elements from paired lists to a new paired list

Some background. I can use Mathematica to generate text book problems/exercises and corresponding answer in two "pairs/synched" lists $L_{Q}$ and $L_{A}$ (i.e. element 1 in each list is a Q&A pair,...

### 2 Subtracting off background data from my data sets

2 answers, 55 views list-manipulation matrix
I don't know how to subtract off background data Data0 from my data sets collected in Datagen. ...

### 4 Change matrix elements at specific locations?

Let's say I have an arraya={{1,2,3}, {4,5,6}, {7,8,9}}I want to have all elements along the diagonal multiplied by 2. ...

### 3 How to assign a list to a desired position of an array?

3 answers, 94 views list-manipulation matrix
This question is related to this. Consider an array array as array = ImageData[RandomImage[10, 10]];And the indices of the ...

### 6 Put an array in a matrix

3 answers, 273 views list-manipulation matrix
Assume that I have a function that generates an $m \times n$ array of numbers and I want to put this array in a specified place in an $(m+n) \times (m+n)$ matrix. How can I do that?

### 1 ListLinePlot of a 3D function, over one of the arguments, with a range of values for the other 2 arguments

1 answers, 38 views plotting list-manipulation table
I have a function of 3 argumentsmu[kx_, ky_, lambda_] := -(kx^2 + ky^2) - (kx^2*(kx^2 + 5*ky^2)*lambda)/(kx^2 + ky^2)^4I want to plot ...

### 2 Optimisation of a loop

I've opened a question here, which was answered. The code works totally fine for a small set of data. However, for a large set and over many iterations, it will take a long time (in order of 24 hours)....

### How to correct not precise values

1 answers, 37 views list-manipulation import precision
I have the source file file = "test.txt" with these values: ...

### 1 Iterative loop for a given list

1 answers, 37 views list-manipulation functions do for
Suppose I have the following list: ...

### 1 Issue with the use of Position

2 answers, 63 views list-manipulation functions
Reading the documentation of Position, I found there's a possible issue:Position looks for matches based on patterns, which may ...

### 5 Subtract lists' elements

I have 2 lists, that have the following form:List1 = {{0.0, val10}, {0.1, val11}, {0.2, val12},...} List2 = {{0.0, val20}, {0.1, val21}, {0.2, val22},...}I ...

### Summing coefficients of multinomial

1 answers, 52 views list-manipulation data
I have data of following form. data = {{1, multi1(z1, z2,..)},{2, multi2(z1, z2,..)},...} I want to add up all the coefficients of corresponding multinomial (and also want to perform different ...

### 7 Deleting list elements by comparing to another list

4 answers, 241 views list-manipulation filtering
I have two lists as follow. The first isp={{"j","d","x"},{"d","k","z"}}and the second one is: ...

### 17 Ordering function with recognition of duplicates

1 answers, 345 views list-manipulation sorting
Fairly often I have a need to get the Ordering of an expression but with recognition of duplicates. For example: ...

### 6 Put edges of a matrix to zero

I have to set the first and last rows and columns to zero rows and columns. I tried with the first column: ...

### 2 labeling data in a list

1 answers, 60 views plotting list-manipulation labeling
I have the following list: l={{1,2},{3,4},{5,6}}I want to list plot above such that the first element {1,2} can be labeled "a", {3,4} labeled "b" and {5,6} to ...

### Identical expressions subtracted from each other giving small but significant errors

0 answers, 29 views list-manipulation precision
In my current code, I have formed a list of numbers with two different methods. For the first method, I wrote ...

### Creating a plot using data imported from Excel

2 answers, 147 views plotting list-manipulation excel
I am trying to create plots starting from values that I have in an Excel spreadsheet. The values of interest are contained in three rows, which I will call 1, 2, and 3 for the sake of this discourse. ...

### 3 Replace non-zero elements with symbol

I have a very large matrix (tensor) in Mathematica with some zero and non-zero elements. I am interested in replacing the non-zero elements with some symbol or a 1 so that it is easier to view the ...

### 7 Nonzero element positions of a matrix

3 answers, 273 views list-manipulation matrix sparse-arrays
Let m={{1, 2, 0}, {4, 0, 9}};I want to find the position of every nonzero element of the above matrix. The code ...