Problem 1972. Convert matrix to 3D array of triangular matrices
Given a 2D numeric array x in which each column represents the vectorized form of an upper triangular matrix, return a 3D array y containing the concatenated triangular matrices.
- If the size of the input matrix x is MxN, then the size of the output matrix y is PxPxN, where M = sum(1:P)
- You may assume that P<=100
Example
If
x = 1 7 13 2 8 14 3 9 15 4 10 16 5 11 17 6 12 18
then
y(:,:,1) = 1 2 4 0 3 5 0 0 6
y(:,:,2) = 7 8 10 0 9 11 0 0 12
y(:,:,3) = 13 14 16 0 15 17 0 0 18
NOTE: If you are wondering why this seems like a strange task, it is inspired by a genotype->phenotype mapping I am doing in a genetic algorithm.
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Indexing II
- 22 Problems
- 161 Finishers
- Getting the indices from a vector
- Symmetry of vector
- Calculate the Number of Sign Changes in a Row Vector (No Element Is Zero)
- Count consecutive 0's in between values of 1
- Find last zero for each column
- Oh Zero Zero Zero!!!
- Create an index-powered vector
- Find nth maximum
- Decimation - Optimized for speed
- Unique values without using UNIQUE function
- Symmetry of vector
- Generate a vector like 1,2,2,3,3,3,4,4,4,4
- Create an n-by-n null matrix and fill with ones certain positions
- Implement a bubble sort technique and output the number of swaps required
- Create a vector whose elements depend on the previous element
- Set a diagonal
- Unique values without using UNIQUE function
- Generate a vector like 1,2,2,3,3,3,4,4,4,4
- Change the sign of even index entries of the reversed vector
- Decimation
- Insert zeros into vector
- Reference Index Number
- Determine the number of odd integers in a vector
- Max index of 3D array
- Finding peaks
- Getting the indices from a vector
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