Question

I have a csv which I would like to process instances of a row[report] based on the input of another row[number].

Report,Number,Name,Date
INC AMT %,12345678,ACME INC,10/30/2012
INC AMT %,12345678,ACME INC,10/31/2012
OUT AMT %,12345678,ACME INC,10/31/2012
# shortened for brevity

My code block looks like this:

require 'CSV'

module AlertHash
  @alert_hash = {}
  CSV.foreach("alerts.csv") do |row|
    report, number = row
    next if number == "Number"
    @alert_hash[number] = report
  end

  def self.report(number)
  @alert_hash[number]
  end

end

puts "Alert: " + AlertHash.report("12345678")
# OUTPUT => Alert: OUT AMT %
# DESIRED OUTPUT => Alert: INC AMT %, OUT AMT % 

I’ve been able to process the last [report]stack of each number. However, my desired output would be to capture ALL reports for a given row[number]. Can someone give me some pointers on how this could be done? Maybe I’m approaching this problem the wrong way.

Answer 1

This statement:

@alert_hash[number] = report

will overwrite any previous value for any given number index, so you only retain the last one. That’s why you get the OUT value only. If you want to collect all lines for a given number, use an array:

@alert_hash[number] ||= [] # initialize array if required
@alert_hash[number] << report # add value

and then concatenate them in your report method:

@alert_hash[number].join(", ")

This will give you:

Alert: INC AMT %, INC AMT %, OUT AMT %

Not sure what you’re actually trying to achieve, but this explains your code’s current behaviour.