36 questions linked to/from Flatten command: matrix as second argument
178 views

### How to remove extra levels in list [duplicate]

My question is how to turn a 4-level matrix (notice one extra level) A = {{{{1, 2, 3}, {4, 5, 6}}}, {{{7, 8, 9}, {10, 11, 12}}}}; into the following: ...
143 views

### How to understand the extensional usage of Flatten? [duplicate]

Recently, I have been reading Mathematica program that written by many advanced Mathematica user, like Mr.Wizard, J.M., Kuba,etc to improve my programming capacity In the On generalizing Partition[] (...
2k views

### Equating matrices (or higher order tensors) element-wise

Say I have two matrices (or, as in my case, higher order tensors) $A,B$, and I want to solve the equation $A=B$. To do so , I need a list of equations that equate entry-wise the elements of $A$ and $B$...
2k views

### Transpose uneven lists

Is there a quick method to transpose uneven lists without conditionals? With: Drop[Table[q, {10}], #] & /@ Range[10] Thus the first list would have the ...
7k views

### Best way to create symmetric matrices

From time to time I need to generate symmetric matrices with relatively expensive cost of element evaluation. Most frequently these are Gram matrices where elements are $L_2$ dot products. Here are ...
3k views

### Ways to compute inner products of tensors

One way to evaluate the following sums is combining Table and Sum: $u_{abcd} = \sum_{e=1}^3 v_{aeb}w_{ced}$ $q_{ab} = \sum_{d,e=1}^3 v_{d e a}w_{deb}$ It will look like ...
846 views

### Prepend 0 to sublists

My question is similar to this one, but my goal is to prepend a single 0 the each sublist, not incrementally many 0's. The file I'm working is a CSV containing around 50K sublists of length 35. I've ...
1k views

### Using Transpose with a list as the second argument

I'm having difficulty understanding the Transpose function. I know what the transpose of a matrix is, not a problem, and I see that applying the ...
6k views

### How to get MATLAB data imported with the same dimensions?

I have some MATLAB image data with the following dimensions (output is from MATLAB): >> size(im) ans = 86 86 3 45 The data imports just fine ...
292 views

### Most efficient way to build block / banded SparseArray

I have a matrix that I generate with a procedure that looks like this: ...
295 views

### Transpose two uneven lists [duplicate]

I am trying to plot two lists using the ListPlot command. I need to merge two lists. The two lists I have are: ...
362 views

### Part of the nested lists

Suppose I have a nested list where sublists have unequal length. How can I extract all values of the list at specific level ignoring errors if the value at that level doesn't exist. For example: <...
288 views

### Riffle two matrices COLUMNWISE; where boh matices have the same number of rows

I need to "riffle" two matrices; COLUMNWISE. Say that we have: ...