Problems with Ruby Arrays - ruby

Question

I am currently writing a small ruby class that is intended to store the amount of times a randomly generated number is seen within an array, along with the value that is seen itself.
I am trying to do the following to add the value along with a default times seen as 1 to the array. The script should check to see if the value has been included within the array and if so, increment the times this value has been seen by 1
However I am recieving duplicate values, which shouldnt happen - as the code should only allow a value to be stored once and if the value is already in the memory array, increment it by one.
The code is attatched below, if anyone can suggest what I am doing wrong it would be awesome.
Cheers
Martin
#memory = Array.new
def store(value)
foundflag = false
#memory.each do |array|
if value == array[0]
#Incrementing value timesseen
array[1] = array[1]+1
#Value found, changing found flag
foundflag = true
#Loop break
break
end
end
if foundflag != true then
#memory.push([value,1])
end
end
store(5)
Full script (untidy!)
class STAT
def initialize()
#STAT memory settings
#memory = Array.new
#Prediction settings
#predictions = 0
#sucessfulpredictions = 0
end
#STAT main functions
def store(value)
foundflag = false
#memory.each do |array|
if value == array[0]
#Incrementing value timesseen
array[1] = array[1]+1
#Value found, changing found flag
foundflag = true
#Loop break
break
end
end
if foundflag != true then
#memory.push([value,1])
end
end
def predict(nosimulations)
#Generate random value less than the total memory size
randomvalue = rand(total)+1
count = 0
#memory.each do |array|
value = array[0]
timesseen = array[1]
if randomvalue <= count + timesseen
puts "Predicted value #{value}"
end
count = count + array[1]
end
end
def simulate(nosimulations)
count = 1
while count <= nosimulations
#Generating a random number
randomnumber = rand(100)+1
#Storing the random number
store(randomnumber)
#Print simulation details#
puts "Running simulation #{count} of #{nosimulations}"
puts "Generated random number: #{randomnumber}"
#Incrementing count
count = count + 1
end
end
#STAT technical functions
def inspect()
#Print memory information message
puts "Memory information:"
#memory.each do |array|
value = array[0]
timesseen = array[1]
puts "Value #{value} - times seen: #{timesseen}/#{total}"
end
end
def total()
total = 0
#memory.each do |array|
total = total + array[1]
end
return total
end
#STAT load/save functions
def load(filename)
#Default engine to be loaded
enginename = "#{filename}.stat"
#Print checking for saved engine message
puts "Checking for saved memory file..."
#Checking for saved engine
if File.exists?(enginename)
#Print loading engine message
puts "Loading memory..."
#memory = Marshal.load File.read(enginename)
#Print engine loaded message
puts "Engine loaded"
else
#Print memory not found message
puts "Cannot load memory, no memory file found"
end
end
def save(filename)
#Default name for engine to be saved
enginename = "#{filename}.stat"
#Print saving engine message
puts "Saving memory..."
#Saving engine to specified file
serialized_array = Marshal.dump(#memory)
savefile = File.new(enginename,"w")
savefile.write(serialized_array)
savefile.close
#Print engine saved message
puts "Memory saved"
end
end
#STAT class test software
stat = STAT.new
filename = "test"
#Load
stat.load(filename)
#Simulate
stat.simulate(1000000)
#Testing
#stat.store(5)
#stat.store(5)
#Inspect
stat.inspect
#Predict
#stat.predict(1000000)
#Save
stat.save(filename)

Answer 1

Use:
occurrences = Hash[ my_array.group_by{ |o| o }.map{ |o,a| [o,a.length] } ]
to get a hash mapping each value to the number of times it occurs. To calculate it yourself:
occurrences = Hash.new(0)
my_array.each{ |o| occurrences[o]+=1 }
See the docs if you don't know what these methods do.

Answer 2

You are working too hard. You want to store the amount of times a randomly generated number is seen within an array, along with the value that is seen itself.
How can Ruby help you with that? Since you are working with an array, glance through the available methods and yes, there it is: count.
ar = [1,2,1,3,2,4,3,2,6,7,8,7]
rn = rand(10)
ar.count(rn)