How print column data given conditions? CSV Ruby

Question

I'm new to programming. Is there a way for Ruby to select the conditions for column 1 and 2, while I print columns 0 and 3 (In the context of the same row)

Take for example I would like to print out the "description" and "equipment" when there is an event type of "high" and severity "1".

I could not print out my equipment and description

require "csv"
equipment = []
description = []
def find_severity(event_type, severity)
    alarms = CSV.read 'alarms.csv', {col_sep: ';'}
    result = alarms.select do |level|
          level[1] == event_type && level[2].to_i == severity.to_i
          equipment[] = level[0]
          description[] = level[3]
    end
end

p find_severity('high', 1)
p equipment
p description

"equipment[] = level[10]" - no, this is not php. Here it's done differently: equipment.push(level[10]). And these should be outside the select, I think. — Sergio Tulentsev
– Sergio Tulentsev, Commented Feb 13, 2018 at 7:58
Also, level[10] and level[13]? What did you mean by that? You only have 4 columns. — Sergio Tulentsev
– Sergio Tulentsev, Commented Feb 13, 2018 at 7:59
The issue is that I would like to check if the event type is 'high' and severity is '1' before printing out 'DT24/SIG Repair doors' and '90430/RSO' 'Repair lift' — Joshua Ng
– Joshua Ng, Commented Feb 13, 2018 at 8:11

Keith Bennett · Accepted Answer · 2018-02-13 10:15:01Z

2

I suggest breaking down the tasks into methods for their respective responsibilities. You have here loading, filtering, and transforming. The methods could reflect that. (I haven't tested this code, but this should show the general idea.)

I think you'd be better off with something like this:

require "csv"

def load_alarms
  CSV.read 'alarms.csv', {col_sep: ';'}
end

def filter_by_event_type_and_severity(alarms, event_type, severity)
  alarms.select do |alarm|
    alarm[1] == event_type && alarm[2].to_i == severity.to_i
  end
end

target_alarms = filter_by_event_type_and_severity(
    load_alarms, 'high', 1)
equipments   = target_alarms.map { |alarm| alarm[0] }
descriptions = target_alarms.map { |alarm| alarm[3] }

p target_alarms
p equipments
p descriptions

Even if the implementations of the methods are trivially simple, this will give you the practice of separating code into logical parts, each of which is highly cohesive or specialized, with minimal coupling (dependency) on other parts of the code.

One of the biggest mistakes of beginners is trying to do too much in the same chunk of code -- high and low level code, and with totally unrelated subjects. Learning how to break problems down into smaller problems, and logically organizing them, is one of the important skills you can learn.

By the way, I don't recommend the to_i call on severity. Since the parameter is logically a number, you shouldn't really permit a string, IMO.

edited Feb 13, 2018 at 10:15

answered Feb 13, 2018 at 8:18

Keith Bennett

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18 Comments

Joshua Ng Over a year ago

Hi for the code 'def filter_by_event_type_and_severity(alarms, event_type, severity)' I get an error "wrong number of arguments (given 2, expected 3") would you know how to fix this? Thanks!

Keith Bennett Over a year ago

Sounds like you're only passing 2 arguments. I added the first argument, the array of records, to what you had. So maybe that's the one that's missing? You can post code to show us; one site for that is gist.github.com.

Joshua Ng Over a year ago

gist.github.com/kaeltharlas/cdeddca2d0d71dbeea40ffa160fbb27b Here's the code. It's the same as yours, could you try to run it? Thanks!

Keith Bennett Over a year ago

One way to create the display line would be to use printf-style formatting to put the entries in aligned columns, like this: eq_and_desc_lines = target_alarms.map { |alarm| "%-15.15s%s" % [alarm[0], alarm[3]] }. You might need to adjust the width setting for proper alignment.

Keith Bennett Over a year ago

target_alarms.map { |alarm| [alarm[0], alarm[3]] }

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