Extracting transaction data from variable length arrays - ruby-on-rails

Question

I have built a small program in ruby that collects table data from my own PDF bank statements. This does so by scanning each PDF statement for tables and then filters out for transactional line item patterns.
Everything is working great and I have managed to collect an array of line items as an array of string arrays. Getting an array of keyed objects would be better but a bit tricky with the format of the statements.
The issue is that the line items have different lengths, so it's kind of tricky to always know the location of the correct values to map.
For example:
["Transaction 1", "1.00"]
["Transaction 2", "Hello World", "3.00"]
["Transaction 3", "Hello World", "feeffe", "5.00"]
["Transaction 4", "Hello World", "feeffe", "5.00", "12.00"]
["Transaction 5", "Hello World # 10.00", "feeffe", "10.00", "12.00"]
The line items only range in between 2 and 5 array items normally.
Is there an efficient/accurate way to map the above to:
{ description: "Transaction 1", amt: "1.00"}
{ description: "Transaction 2 - Hello World", amt: "3.00"}
{ description: "Transaction 3 - Hello World - feeffe", amt: "5.00"}
{ description: "Transaction 4 - Hello World - feeffe", amt: "5.00"}
{ description: "Transaction 5 - Hello World # 10.00 - feeffe", amt: "10.00"}
-Or is the only way to write IF conditions that looks at the array length and makes a "best guess" effort?

Answer 1

If you are having,
row = ["Transaction 2", "Hello World", "3.00"]
You can follow by doing,
{ description: row[0..-2].join(' - '), amt: row[-1] }
You have to further manipulate how these rows get iterated so further logic will vary.
update:
For condition updated specified later, it is seen to have row can have length 5 where actual amount is second last value.
data = (row.length == 5) ? [row[0..-3], row[-2]] : [row[0..-2], row[-1]]
{ description: data[0].join(' - '), amt: data[1] }

Answer 2

Assume your transaction is on a variable tr, i.e.
tr=["Transaction 5", "Hello World", "feeffe", "10.00", "12.00"]
I would first separtate this into those strings which look like an amount, and those which don't:
amounts,texts= tr.partition {|el| /^\d+[.]\d{2}/ =~ el}
Here you can check that !amounts.empty?, to guard agains transaction without amount. Now your hash could be
{
transaction_name: texts.first,
transaction_text: "#{texts[1]}#{amounts.size > 1 ? %( # #{amounts.first}) : ''}#{texts.size > 2 ? %( - #{texts.last}) : ''}",
amt: amounts.last
}

Answer 3

Try this regex:
"\K[^",\]]+
Here is Demo

Answer 4

If the number of items always determines the index of the amount element, you can do something like:
input = [
["Transaction 1", "1.00"],
["Transaction 2", "Hello World", "3.00"],
["Transaction 3", "Hello World", "feeffe", "5.00"],
["Transaction 4", "Hello World", "feeffe", "5.00", "12.00"],
["Transaction 5", "Hello World # 10.00", "feeffe", "10.00", "12.00"]
]
ROW_LENGTH_TO_AMOUNT_INDEX = {
2 => 1,
3 => 2,
4 => 3,
5 => 3,
}
def map(transactions)
transactions.map do |row|
amount_index = ROW_LENGTH_TO_AMOUNT_INDEX[row.length]
{
description: row[0],
amt: row[amount_index]
}
end
end
p map(input)
[{:description=>"Transaction 1", :amt=>"1.00"}, {:description=>"Transaction 2", :amt=>"3.00"}, {:description=>"Transaction 3", :amt=>"5.00"}, {:description=>"Transaction 4", :amt=>"5.00"}, {:description=>"Transaction 5", :amt=>"10.00"}]
Or, perhaps something like this?
MAPPERS = {
2 => lambda { |row| { description: row[0], amt: row[1]} },
3 => lambda { |row| { description: row[0], amt: row[2]} },
4 => lambda { |row| { description: row[0], amt: row[3]} },
5 => lambda { |row| { description: row[0], amt: row[3]} }
}
def map(transactions)
transactions.map do |row|
MAPPERS[row.length].call(row)
end
end

Answer 5

arr = [["Transaction 1", "1.00"],
["Transaction 2", "Hello World", "3.00"],
["Transaction 3", "Hello World", "feeffe", "5.00"]]
arr.map {|*first, last| { description: first.join(' - '), amt: last } }
#=> [{:description=>"Transaction 1", :amt=>"1.00"},
# {:description=>"Transaction 2 - Hello World", :amt=>"3.00"},
# {:description=>"Transaction 3 - Hello World - feeffe", :amt=>"5.00"}]