I'm trying to find the indexes where a specific string is located in a multidimensional array in Ruby. I'm using the following code.
array = [['x', 'x',' x','x'], ['x', 'S',' ','x'], ['x', 'x','x','S']] array.index(array.detect{|aa| aa.include?('S')} However, this only returns 1 (the first index). Does anyone know how I can alter this command to return all the indexes where the pattern is present? This example should return 1 and 2.
Here's the updated solution now that you updated your question and added the below comment:
array.each_index.select { |i| array[i].include?('S') } #=> [1, 2] 
One way:
array = [['x', 'x',' x','x'], ['x', 'S',' ','x'], ['x', 'x','x','S']] array.each_with_index.with_object([]) do |(row,i),arr| j = row.index('S') arr << i unless j.nil? end #=> [1, 2] It's only a small change to retrieve both the row and column indices (assuming there is at most one target string per row):
array.each_with_index.with_object([]) do |(row,i),arr| j = row.index('S') arr << [i,j] unless j.nil? end #=> [[1, 1], [2, 3]] You can also use the Matrix class to obtain row/column pairs.
require 'matrix' Matrix[*array].each_with_index.with_object([]) { |(e,i,j),arr| arr << [i,j] if e == 'S' } #=> [[1, 1], [2, 3]] each.with_index.with_object([]) has a nice symmetry (i.e. just chaining all the Enumerable methods)? :)
Enumerable again when I meant Enumerator. One day I'll get this right... ;)