Problem 856. Getting the indices from a matrix

Created by Jean-Marie Sainthillier
Appears in Indexing I

Difficulty:Rate

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Inspired by Problem 645.
Getting the indices from a matrix. 
Given a matrix A (or a vector), return the indices (always in row) where A is greater than scalar, thresh. More instructive without FIND instruction.

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Last Solution submitted on Apr 04, 2025

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Indexing I

27 Problems
236 Finishers

Piecewise linear interpolation
Longest run of consecutive numbers
Construct an index vector from two input vectors in vectorized fashion
Getting the indices from a matrix
First non-zero element in each column
Return unique values without sorting
Return a list sorted by number of consecutive occurrences
intersection of matrices
Generate N equally spaced intervals between -L and L
Check if number exists in vector
Replicate elements in vectors
We love vectorized solutions. Problem 1 : remove the row average.
intersection of matrices
Generate N equally spaced intervals between -L and L
Create logical matrix with a specific row and column sums
Return a list sorted by number of consecutive occurrences
Replicate elements in vectors
Get the elements of diagonal and antidiagonal for any m-by-n matrix
Getting the indices from a matrix
Check if number exists in vector
Fill a zeros matrix
Set the array elements whose value is 13 to 0
Construct an index vector from two input vectors in vectorized fashion
Joining Ranges
Remove the two elements next to NaN value
Reindex a vector
Longest run of consecutive numbers
Put two time series onto the same time basis
Getting logical indexes
Matrix indexing with two vectors of indices
middleAsColumn: Return all but first and last element as a column vector
Return elements unique to either input
"Low : High - Low : High - Turn around " -- Create a subindices vector
Return unique values without sorting
Find the largest value in the 3D matrix
Specific Element Count
First non-zero element in each column

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