Question

Maybe somebody can help me.

Starting with a CSV file like so:

Ticker,"Price","Market Cap"
ZUMZ,30.00,933.90
XTEX,16.02,811.57
AAC,9.83,80.02

I manage to read them into an array:

require 'csv'
tickers = CSV.read("stocks.csv", {:headers => true, :return_headers => true, :header_converters => :symbol, :converters => :all} )

To verify data, this works:

puts tickers[1][:ticker]
ZUMZ

However this doesn’t:

puts tickers[:ticker => "XTEX"][:price]

How would I go about turning this array into a hash using the ticker field as unique key, such that I could easily look up any other field associatively as defined in line 1 of the input? Dealing with many more columns and rows.

Much appreciated!

Answer 1

To get the best of both worlds (very fast reading from a huge file AND the benefits of a native Ruby CSV object) my code had since evolved into this method:

$stock="XTEX"
csv_data = CSV.parse IO.read(%`|sed -n "1p; /^#{$stock},/p" stocks.csv`), {:headers => true, :return_headers => false, :header_converters => :symbol, :converters => :all}

# Now the 1-row CSV object is ready for use, eg:
$company = csv_data[:company][0]
$volatility_month = csv_data[:volatility_month][0].to_f
$sector = csv_data[:sector][0]
$industry = csv_data[:industry][0]
$rsi14d = csv_data[:relative_strength_index_14][0].to_f

which is closer to my original method, but only reads in one record plus line 1 of the input csv file containing the headers. The inline sed instructions take care of that–and the whole thing is noticably instant. This this is better than last because now I can access all the fields from Ruby, and associatively, not caring about column numbers anymore as was the case with awk.