I am trying to take in a 2D array, search for any space that is greater than 0, then increment the surrounding spaces by 1.
array = [[0,0,0], [0,1,0], [0,0,0]]
The final output should look like this
new_array = [[0,1,0], [1,1,1], [0,1,0]]
The way I have it set up currently is returning
[1,1,1,1]
It is incrementing the correct spaces, I think, I just am not sure how to put them back into the original arrays and then return the 2D array. Clearly some steps are missing, any help would be greatly appreciated. I understand why it is returning the way it is, just not clear on the next step.
def dilate(array) new_array = [] array.each_with_index do |row, rowIndex| row.each_with_index do |col, colIndex| if (array[rowIndex][colIndex] > 0) new_array << (array[rowIndex][colIndex -1] +1) new_array << (array[rowIndex -1][colIndex] +1) new_array << (array[rowIndex][colIndex +1] +1) new_array << (array[rowIndex +1][colIndex] +1) end end end return new_array end
What you're doing is initializing an empty array, new_array, and appending elements to it. You're appending the incremented values to a new array instead of changing the values in the array. Something like this should work:
def dilate(array) new_array=[] array.each{|i|new_array<<i.dup} array.each_with_index do |row, rowIndex| row.each_with_index do |col, colIndex| if (array[rowIndex][colIndex] > 0) new_array[rowIndex][colIndex -1] += 1 if colIndex > 0 new_array[rowIndex -1][colIndex] += 1 if rowIndex > 0 new_array[rowIndex][colIndex +1] += 1 if colIndex < array.first.size-1 new_array[rowIndex +1][colIndex] += 1 if rowIndex < array.size-1 end end end return new_array end
I'm creating a new array, new_array, that's a copy of array, then incrementing its elements.
By the way, you say in your question that you want to "search for any space that contains a 1", but what this is doing is searching for spaces containing values greater than zero. I'm not sure if that's what you wanted.
I suggest you use the class Matrix for this. It makes it easy to do and easy to read.
Code
require 'matrix' def dilate(arr) nrows, ncols = arr.size, arr[0].size m = Matrix[*arr] m.each_with_index.reduce(m.dup) { |mout, (e, row, col)| mout + Matrix.build(nrows, ncols) { |i,j| adjacent?(i,j,row,col) ? e : 0 } }.to_a end def adjacent?(r0,c0,r1,c1) ((r0-r1).abs == 1 && (c0==c1)) || ((c0-c1).abs == 1 && (r0==r1)) end
I have assumed that, when the value of an element, x, is non-zero, you want to increase the values of adjacent elements by x. If you want to increase the values of adjacent elements by 1, change:
Matrix.build(nrows, ncols) { |i,j| adjacent?(i,j,row,col) ? e : 0 }
to:
Matrix.build(nrows, ncols) { |i,j| adjacent?(i,j,row,col) ? 1 : 0 }
Examples
arr = [[0, 0, 0], [0, 1, 0], [0, 0, 0]] dilate(arr) #=> [[0, 1, 0], # [1, 1, 1], # [0, 1, 0]] arr = [[0, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 0]] dilate(arr) #=> [[0, 1, 0, 0], # [1, 1, 1, 0], # [0, 1, 0, 0]] arr = [[1, 0, 0], [0, 0, 0], [0, 0, 0]] dilate(arr) #=> [[1, 1, 0], # [1, 0, 0], # [0, 0, 0]]
arr = [[0, 0, 0], [1, 0, 0], [0, 0, 0]] dilate(arr) #=> [[1, 0, 0], # [1, 1, 0], # [1, 0, 0]] arr = [[0, 0, 1], [0, 0, 0], [0, 0, 0]] dilate(arr) #=> [[0, 1, 1], # [0, 0, 1], # [0, 0, 0]] arr = [[0, 0, 0, 3], [0, 1, 1, 0], [0, 4, 1, 0], [2, 0, 0, 0]] dilate(arr) #=> [[0, 1, 4, 3], # [1, 6, 3, 4], # [6, 6, 6, 1], # [2, 6, 1, 0]]
