Ruby - Split file line into array with index in array name

Question

This is a very specific question (which I doubt most will be able to benefit from) but I'll explain:

I have an example file which contains numbers split by commas on each line:

1,2,3,4
5,6,7,8
abcdefg
1.3.4

I want to be able to split the file into lines (easily done):

file = File.open(filename)
file = file.read.split("\n")

And now I want to split each line into an array if it includes "," and have the name or the array be something like: 1array (with 1 being the file line index)

Something like this would be preferable:

file.each_with_index |c, i| do # c=content, i=index
  if c.include? ","
    instance_array_set("@#{i}array", c.split(","))
  end
end

I've looked everywhere for anything on an instance array concept but I can't seem to find anything. I am open to completely different ways of doing what I'm trying to do (as long as it's not too long).

Thanks in advance (hopefully)

Ursus · Accepted Answer · 2018-09-08 16:39:09Z

1

Variables' identifiers can't start with a digit so I move it to the end of the name

File.open(filename).read.split("\n").each_with_index do |item, index|
  if item.include?(",")
    instance_variable_set("@array#{index}", item.split(","))
  end
end

answered Sep 8, 2018 at 16:39

Ursus

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8 Comments

notsoscottishscot Over a year ago

So instance variables don't need to be single variables? They can be arrays as well?

Ursus Over a year ago

of course. they are just names. you can assign anything to a variable

notsoscottishscot Over a year ago

Now I think about it, that makes a whole lot of sense. Thanks. Also, how would I go about calling one of the instance variables that I don't know the name of? For example: array1 = 1 array2 = 2 array3 = 3 i=1 Could I call array1 like this?: array#{i} = 1+1

Ursus Over a year ago

Well, you're right. In fact, I don't know why you prefer set instance variables rather then have a result array with every array who pass the test in it. So that you can iterate it, take a random array from it or do whatever you want to

Cary Swoveland Over a year ago

Consider using IO::foreach to avoid the creation of a temporary array: File.foreach(fname).with_index { |line,i| instance_variable_set("@array#{index}", line.chomp.split(",")) }.

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Aleksei Matiushkin · Accepted Answer · 2018-09-08 17:27:49Z

0

Build an array of arrays:

result =
  File.readlines('/tmp/input').map do |line|
    values = line.chomp.split(',')
    values if values.size >= 2
  end.compact

result[0][2]
#⇒ "3"

answered Sep 8, 2018 at 17:27

Aleksei Matiushkin

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Comments

iGian · Accepted Answer · 2018-09-08 21:31:30Z

0

Yet another version:

File.readlines(filename).select{ |e| e.split("").include? "," }.map{ |e| e.chomp.split "," }

# => [["1", "2", "3", "4"], ["5", "6", "7", "8"], ["11", "12", "13"]]

answered Sep 8, 2018 at 21:31

iGian

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