How to parse text file in Ruby on Rails

Question

Below is the text file:

Old count: 56
S id: 1
M id: 1 
New count: 2
Old count: 56
S id: 1
M id: 2
New count: 20
Old count: 56
S id: 1
M id: 2
New count: 32
-----------------------------
Old count: 2
S id: 2
M id: 1
New count: 4
--------------------------------
.
.
.
.

I have used delimiter "---------------" for each ids.

How to parse the value such that the lines with in the delimiter "-----" that is new count is added like this: 2+20+32 = 54

Hash array: count << {'new count' => 54} for first block and so on for remaining blocks.

I have tried like this..

begin
f=File.open("out2", "r")
f.each_line do |line|
@data+=line
end

[email protected]("------")
s_rec.each do |rec|
row_s=rec.split(/\n/)

row_s.each do |row|

  if r.include?"New count"
    rv=row.split(":")
    @db=rv[1]
  end

  end
  end

Why is 69 not added? In your text, you have "New count" but you don't have 'new count'. — sawa
– sawa, Commented Apr 20, 2013 at 10:01

sawa · Accepted Answer · 2013-04-20 10:58:39Z

1

Not sure what output format you are trying to achieve, but given the text:

text = <<__
Old count: 56
S id: 1
M id: 1 
New count: 2
Old count: 56
S id: 1
M id: 2
New count: 20
Old count: 56
S id: 1
M id: 2
New count: 32
-----------------------------
Old count: 2
S id: 2
M id: 1
New count: 4
--------------------------------
.
.
.
.
__

this:

text
.split(/^-{5,}/)
.map{|s| s.scan(/\bNew count: (\d+)/).map{|match| match.first.to_i}.inject(:+)}

gives:

[
  54,
  4,
  nil
]

In response to the comment, still not clear what you want because what you wrote is not a valid Ruby object, but this:

text
.scan(/^S id: (\d+).+?^New count: (\d+)/m)
.inject(Hash.new(0)){|h, (k, v)| h[k.to_i] += v.to_i; h}
.map{|k, v| {"S id" => k, "new count" => v}}

gives:

[
  {
    "S id"      => 1,
    "new count" => 54
  },
  {
    "S id"      => 2,
    "new count" => 4
  }
]

edited Apr 20, 2013 at 10:58

answered Apr 20, 2013 at 10:10

sawa

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1 Comment

user2244199 Over a year ago

I am expecting output like this { 'S id'=>1, 'new count'=>54 } {'S id'=>2, 'new count'=>4}

the Tin Man · Accepted Answer · 2013-04-20 15:45:53Z

I'd start with:

data = 'Old count: 56
S id: 1
M id: 1 
New count: 2
Old count: 56
S id: 1
M id: 2
New count: 20
Old count: 56
S id: 1
M id: 2
New count: 32
-----------------------------
Old count: 2
S id: 2
M id: 1
New count: 4
--------------------------------
'

ary = data.split("\n").slice_before(/^---/).map{ |a| a.select{ |s| s['New count:'] }.map{ |s| s[/\d+/].to_i }.inject(:+) }.compact

Which gives me an array:

[
    [0] 54,
    [1] 4,
]

compact is needed because there's a trailing ---- block delimiter that results in an empty array when slice_before does its magic.

From that point it's easy to create an array of hashes:

Hash[ ary.map.with_index(1) { |v, i| ["S #{ i }", "new count #{ v }" ] } ]

Which looks like:

{
    "S 1" => "new count 54",
    "S 2" => "new count 4"
}

Breaking it down, the code through slice_before returns:

[
    [0] [
        [ 0] "--------------------------------",
        [ 1] "Old count: 56",
        [ 2] "S id: 1",
        [ 3] "M id: 1 ",
        [ 4] "New count: 2",
        [ 5] "Old count: 56",
        [ 6] "S id: 1",
        [ 7] "M id: 2",
        [ 8] "New count: 20",
        [ 9] "Old count: 56",
        [10] "S id: 1",
        [11] "M id: 2",
        [12] "New count: 32"
    ],
    [1] [
        [0] "-----------------------------",
        [1] "Old count: 2",
        [2] "S id: 2",
        [3] "M id: 1",
        [4] "New count: 4"
    ]
]

From there it's straightforward, selecting the lines that are needed in each sub-array, extracting out the values, and summing them using inject.

Once that's done it's simply using map and with_index to build the string and name/value pairs, then let Hash turn them into a hash.

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