Changing elements in multi-dimensional array - ruby

Question

Inside arrays, I have 0s and one 1.
class Image
def initialize(rows)
#rows = rows
end
end
image = Image.new([
[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0],
])
I want the numbers that are located up, down, left, and right to turn 1 as well. I tried to do this by manipulating column_index and row_index. The code is:
class Image
def blur
#rows_copy = Array.new(#rows.size) {Array.new(#rows.first.size)}
#rows.each_with_index do |row, row_index|
row.each_with_index do |cell, column_index|
blur_location(row_index,column_index)
end
end
#rows = #rows_copy
end
def blur_location (row_index, column_index)
if #rows[row_index][column_index] == 1
#rows_copy[row_index][column_index] = 1
#rows_copy[row_index + 1][column_index] = 1
#rows_copy[row_index - 1][column_index] = 1
#rows_copy[row_index][column_index + 1] = 1
#rows_copy[row_index][column_index - 1] = 1
else
#rows_copy[row_index][column_index] = 0
end
end
def output_image
#rows.each_with_index do |row, row_index|
puts row.join('')
end
end
end
image.blur
image.output_image
But only half of the code is working (i.e., the top and left turns to 1, but not the other two).

Answer 1

the code almost works as expected but you are a victim of the following piece of code:
else
#rows_copy[row_index][column_index] = 0
end
What happens is the when you hit the '1' you set everything as expected, but when you move on and you hit the zeros that are near the '1' (to the right and down as you're processing) you are resetting the rows_copy to zero.
Here is a revised version of the code the does the right thing (notice how the copy is all first set to 0 and after that only 1s are marked):
#!/usr/bin/env ruby
class Image
def initialize(rows)
#rows = rows
end
def blur
#rows_copy = Array.new(#rows.size) {Array.new(#rows.first.size)}
#rows.each_with_index do |row, row_index|
row.each_with_index do |cell, column_index|
set_zero(row_index,column_index)
end
end
#rows.each_with_index do |row, row_index|
row.each_with_index do |cell, column_index|
blur_location(row_index,column_index)
end
end
#rows = #rows_copy
end
def set_zero(row_index, column_index)
#rows_copy[row_index][column_index] = 0
end
def blur_location (row_index, column_index)
if #rows[row_index][column_index] == 1
#rows_copy[row_index][column_index] = 1
#rows_copy[row_index + 1][column_index] = 1
#rows_copy[row_index - 1][column_index] = 1
#rows_copy[row_index][column_index + 1] = 1
#rows_copy[row_index][column_index - 1] = 1
end
end
def output_image
#rows.each_with_index do |row, row_index|
puts row.join('')
end
end
end
image = Image.new([
[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 0, 0],
[0, 0, 0, 0],
])
image.blur
image.output_image