Ruby - Retrieve stock market data and graph moving averages with gnuplot

#!/usr/bin/ruby
#
# Matt Feenstra 04/11/16
# original work
##########################



require "yahoo-finance"

$TICKER = nil
$maxDaysHistory = 3650   # 10 years default
$start_day = nil


### syntax check

if $ARGV[0] =~ /\w+/ && $ARGV[1] =~ /\d+/ then
$TICKER = $ARGV[0]
$maxDaysHistory = Integer($ARGV[1])
print "max days history is #{$maxDaysHistory}\n"
elsif $ARGV[0] =~ /\w+/ then
$TICKER = $ARGV[0]
else
STDERR.puts "incorrect syntax:\t#{$0} #{$ARGV[0]} #{$ARGV[1]}\n"
abort "correct syntax:\t\t#{$0} <TICKER SYMBOL> <NUMBER of DAYS>"
end


################### functions

def get_data
STDERR.puts "getting data for #{$TICKER} from yahoo finance..\n"
yahoo_client = YahooFinance::Client.new
data_download = yahoo_client.historical_quotes($TICKER)

data = Array.new
$start_day = data_download.reverse[$maxDaysHistory].trade_date
STDERR.puts "starting day 0 on #{$start_day}\n"
i = 0
data_download.reverse.each do |value|
#puts "#{i} #{value.adjusted_close}"

if i < $maxDaysHistory.to_f then
data.push value.adjusted_close
end

i += 1
end # data_download.each
data
end


def get_avg(data_ary, radius)

i = 0
y = 0
fiftyday = Array.new

for num in 0..radius
fiftyday[num] = 0
end

data_ary.each do |price|

if i > (radius - 1) && i < (data_ary.length - radius) then

subary = Array.new
#puts "subary will be data_ary from #{i-radius} to #{i+radius}\n"
subary = data_ary[i-radius..i+radius]
sum = 0
#puts "averaging sub ary indexes #{i-radius} to #{i+radius}\n"
y = 0
subary.each do |pricenum|
#puts "  adding subary(#{y}) value: #{pricenum} to #{sum}\n"
sum = sum + pricenum.to_f
y += 1
end
subary.slice(0)
#puts "sum is #{sum} average is #{sum/(2*radius)}\n"
fiftyday[i] = sum / (2*radius)

end
i += 1
end

fiftyday
end

def make_graph_file(data_ary, filename)

puts "writing #{filename}\n"
`rm -rf #{filename} 1>>/dev/null 2>>/dev/null`
file = File.open(filename, "w")
i = 0
data_ary.each do |value|
file.puts "#{i} #{value}"
i += 1
end
file.close

end

################## main


data = get_data
dataFile = "#{$TICKER}.data"
make_graph_file(data, dataFile)

STDERR.puts "calculating 20 day average graph..\n"
twentyDayAvg = get_avg(data, 10)
twentyDayFile = "#{$TICKER}.20.data"
make_graph_file(twentyDayAvg, twentyDayFile)

STDERR.puts "calculating 50 day average graph..\n"
fiftyDayAvg = get_avg(data, 25)
fiftyDayFile = "#{$TICKER}.50.data"
make_graph_file(fiftyDayAvg, fiftyDayFile)

STDERR.puts "calculating 100 day average graph..\n"
hundredDayAvg = get_avg(data, 50)
hundredDayFile = "#{$TICKER}.100.data"
make_graph_file(hundredDayAvg, hundredDayFile)

STDERR.puts "calculating 200 day average graph..\n"
twohundredDayAvg = get_avg(data,100)
twohundredDayFile = "#{$TICKER}.200.data"
make_graph_file(twohundredDayAvg, twohundredDayFile)

STDERR.puts "calculating 500 day average graph..\n"
fivehundredDayAvg = get_avg(data,250)
fivehundredDayFile = "#{$TICKER}.500.data"
make_graph_file(fivehundredDayAvg, fivehundredDayFile)

STDERR.puts "calculating 800 day average graph..\n"
eighthundredDayAvg = get_avg(data,400)
eighthundredDayFile = "#{$TICKER}.800.data"
make_graph_file(eighthundredDayAvg, eighthundredDayFile)

STDERR.puts "calculating 1000 day average graph..\n"
thousandDayAvg = get_avg(data,500)
thousandDayFile = "#{$TICKER}.1000.data"
make_graph_file(thousandDayAvg, thousandDayFile)

# gnuplot script

gnuFilename = "#{$TICKER}.script"
gnuPlot = "plot \"#{dataFile}\", \"#{twentyDayFile}\" with lines, "\
 "\"#{fiftyDayFile}\" with lines, \"#{hundredDayFile}\" with lines lw 2, "\
 "\"#{twohundredDayFile}\" with lines lw 3 lt -1, "\
 "\"#{fivehundredDayFile}\" with lines lw 4 lt 5, "\
 "\"#{eighthundredDayFile}\" with lines lw 3 lt rgb \"grey\", "\
 "\"#{thousandDayFile}\" with lines lw 5 lt rgb \"magenta\""

gnuPause = "pause -1 \"hit any key to continue..\""
gnuPic = "set term png size 1024,768\nset output \"#{$TICKER}-#{$maxDaysHistory}.png\"\nreplot\nset term x11"

`rm -rf #{gnuFilename} 1>>/dev/null 2>>/dev/null`
gnuFile = File.open(gnuFilename, "w")
gnuFile.puts "set title \"stock price vs. time\""
gnuFile.puts "set xlabel \"#{$maxDaysHistory} days since #{$start_day}\""
gnuFile.puts "set ylabel \"Stock price\""
gnuFile.puts "set key left"
gnuFile.puts gnuPlot
gnuFile.puts gnuPause
gnuFile.puts gnuPic
gnuFile.close

`gnuplot #{gnuFilename}`
`rm *.data; rm #{gnuFilename}`