Chaining methods issue [closed] - ruby

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So I have a CSV that looks like this;
This is a test file
,,,,,,,,,,,
1122,Foo,Bar,FooBar
22321,Bar,Bar,Foo
11223,Foo,Foo,Foo,,,,,,,,,
12312/2423/1245,Foo,Foo,,,,,,,,
I want to parse it and have the following result in my array;
1122,Foo,Bar,FooBar
11223,Foo,Foo,Foo
22321,Bar,Bar,Foo
12312/2423/1245,Foo,Foo
My code;
class ReadCSVToArray
def initialize(file)
#array = CSV.read(file)
end
def compact_multi
y = []
#array.each { |i| i.compact! ; y << i unless i.blank? }
end
def item_rows
y = []
#array.each { |o|
if o[0].include? '/'; y << o ; end
if o[0].is_number? ; y << o ; end
}
end
end
the_list = ReadCSVToArray.new('/Users/davidteren/Desktop/read_test.csv')
the_list.compact_multi.item_rows.sort.each { |i| p i }
So as per above I'd like to chain several methods to get my results.
I have tried various things like;
class ReadCSVToArray
def initialize(file)
#array = CSV.read(file)
end
def compact_multi
y = []
#array.each { |i| i.compact! ; y << i unless i.blank? }
self
end
def item_rows
y = []
#array.each { |o|
if o[0].include? '/'; y << o ; end
if o[0].is_number? ; y << o ; end
}
self
end
end
No matter what I try I can't get it to work.

Answer 1

There's a problem with this line:
the_list.compact_multi.item_rows.sort.each { |i| p i }
This chain breaks down to 4 method calls:
the_list.compact_multi
the_list.item_rows
the_list.sort
the_list.each { |i| p i }
By returning self in your compact_multi and item_rows methods, you're ensuring that the next method in the chain is sent to your ReadCSVToArray instance. But there are no ReadCVSToArray#sort or ReadCSVToArray#each methods. You probably want to call them on instance variable #array.

Answer 2

result = CSV.parse 'This is a test file
,,,,,,,,,,,
1122,Foo,Bar,FooBar
22321,Bar,Bar,Foo
11223,Foo,Foo,Foo,,,,,,,,,
12312/2423/1245,Foo,Foo,,,,,,,,'
result.map(&:compact).reject { |l| l.size < 2 }
#⇒ [["1122", "Foo", "Bar", "FooBar"], ["22321", "Bar", "Bar", "Foo"],
# ["11223", "Foo", "Foo", "Foo"], ["12312/2423/1245", "Foo", "Foo"]]
Please note, that rejecting empties probably should be done more accurate. Hope it helps.
To get this:
the_list.compact_multi.item_rows.sort.each { |i| p i }
to work, compact_multi should return self and item_rows should return #array.

Answer 3

You seem to have two issues, the method chaining and getting the right result...
Your right result issue seems to be that you're assigning and building out this y array but you're not doing anything with it in any of those methods...
def compact_multi
y = []
#array.each { |i| i.compact! ; y << i unless i.blank? }
self
end
def item_rows
y = []
#array.each { |o|
if o[0].include? '/'; y << o ; end
if o[0].is_number? ; y << o ; end
}
self
end
what exactly is your goal? if its to maintain a result through the y array then make that an instance variable and initialize it in the initialize method...
As far as your chaining method issue if it's what I think you're trying to do which is unclear by your question then your methods should look like this...
class ReadCSVToArray
def initialize(file)
#result = []
#csv = CSV.read(file)
end
def compact_multi
#csv.each { |i| i.compact! ; #result << i unless i.blank? }
self
end
def item_rows
#csv.each { |o|
if o[0].include? '/'; #result << o ; end
if o[0].is_number? ; #result << o ; end
}
#result
end
end