Illustration of using tail conditions for http://stackoverflow.com/a/14460975/693538 SO answer

conditions.rb

# Check if it is present...
if row[1].present?
 # If it is present:
  # Check if it is a subclass of numeric...
  if row[1].is_a? Numeric
   # If it is present AND it is a number:
    oem = row[1].to_i.to_s # <- Convert it to string
  else
    # If it is present BUT is not a number:
    oem = row[1] # ...then it is string, conversion not required
  end
else
 # If it is NOT present:
  oem = nil
end

# OR (shorter) -- using such feature of Ruby that every statement returns its value, even 'if' does it (returns last statement of executed branch)

oem = if row[1].present?
        if row[1].is_a? Numeric
          row[1].to_i.to_s
        else
          row[1]
        end
      end

# OR (even shorter)

oem = if row[1].present?
        row[1].is_a?(Numeric) ? row[1].to_i.to_s : row[1]
      end

# FINALLY (one-liner) -- the BEST one

oem = row[1].is_a?(Numeric) ? row[1].to_i.to_s : row[1] if row[1].present?

# OR EVEN (with ?: operators) -- the WORST one

oem = row[1].present? ? ( row[1].is_a?(Numeric) ? row[1].to_i.to_s : row[1] ) : nil  # OH SHI-- how many '?' signs!