Ruby - Cannot sum up hash values - ruby

Question

I'm new to Ruby (and programming in general). I have a hash that is using data from an external file, and I'm trying to get the total number of values that are greater than 1500.
Here's my code Actually, I need both the number of entries and the total value of purchase orders over 1500. The external file is just a column of order numbers and a column of prices. I'm sure there is a very simple solution, but like I said I'm a beginner and can't figure it out. Any help would be appreciated. Thanks.
Edit: Here is my code. It's just that last while loop that's causing all the problems. I know that's not the right way to go about it, but I just can't figure out what to do.
myhash={}
file=File.open("Purchase Orders.csv", "r")
while !file.eof
line=file.readline
key,value=line.chomp.split(",")
myhash[key]=value
end
total=0
entries=myhash.length
newtotal=0
myhash.each { |key,value|
total+=value.to_f
}
puts total
puts entries
while value.to_f>1500
myhash.each {|key,value| newtotal+=value.to_f}
end
puts newtotal

Answer 1

I will rewrite the code in ruby idiomatic way in hope you’ll examine it and find out some hints.
prices = File.readlines("Purchase Orders.csv").map do |line|
line.chomp.split(",").last.to_f
end # array of prices
total = prices.inject(:+) # sum values
pricy = prices.select { |v| v > 1500 }
pricy_sum = pricy.inject(:+) # sum expensives
pricy_count = pricy.length # expensives’ size
puts "Total sum is: #{total}"
puts "Total expensives is: #{pricy}"

Answer 2

looks like you have your loops reversed. Also, using do and end is usually preferred over curly braces for multiline code blocks, while curly braces are generally used for single line blocks (as noted by #mudasobwa). Check out the ruby style guide for some more style pointers.
myhash.each do |key,value|
newtotal+=value.to_f if value.to_f > 1500
end
puts newtotal

Answer 3

Code
def nbr_and_tot(fname)
File.foreach(fname).with_object({ nbr_over: 0, tot_over: 0 }) do |line, h|
n = line[/\d+/].to_i
if n > 1500
h[:nbr_over] += 1
h[:tot_over] += n
end
end
end
Example
First let's create a file "temp":
str =<<-END
:cat, 1501
:dog, 1500
:pig, 2000
END
File.write("temp", str)
#=> 33
Confirm the file is correct:
puts File.read("temp")
prints
:cat, 1501
:dog, 1500
:pig, 2000
Now execute the method.
nbr_and_tot "temp"
#=> {:nbr_over=>2, :tot_over=>3501}
Explanation
First review, as necessary, IO::foreach, which reads the file line-by-line1 and returns an enumerator that is chained to with_object, Enumerator#with_object and String#[].
For the example,
fname = "temp"
e0 = File.foreach(fname)
#=> #<Enumerator: File:foreach("temp")>
We can see the values that will be generated by this enumerator (and passed to each_object) by converting it to an array:
e0.to_a
#=> [":cat, 1501\n", ":dog, 1500\n", ":pig, 2000\n"]
Continuing,
e1 = e0.with_object({ nbr_over: 0, tot_over: 0 })
#=> #<Enumerator: #<Enumerator: 2.3.0 :171 >
e1.to_a
#=> [[":cat, 1501\n", {:nbr_over=>0, :tot_over=>0}],
# [":dog, 1500\n", {:nbr_over=>0, :tot_over=>0}],
# [":pig, 2000\n", {:nbr_over=>0, :tot_over=>0}]]
The first element generated by e1 is passed to the block and the block variables are assigned values, using parallel assignment:
line, h = e1.next
#=> [":cat, 1501\n", {:nbr_over=>0, :tot_over=>0}]
line
#=> ":cat, 1501\n"
h #=> {:nbr_over=>0, :tot_over=>0}
and n is computed:
s = line[/\d+/]
#=> "1501"
n = s.to_i
#=> 1501
As n > 1500 #=> true, we perform the following operations:
h[:nbr_over] += 1
#=> 1
h[:tot_over] += n
#=> 1501
so now
h #=> {:nbr_over=>1, :tot_over=>1501}
Now the second element of e1 is passed to the block and the following steps are performed:
line, h = e1.next
#=> [":dog, 1500\n", {:nbr_over=>1, :tot_over=>1501}]
line
#=> ":dog, 1500\n"
h #=> {:nbr_over=>1, :tot_over=>1501}
n = line[/\d+/].to_i
#=> 1500
As n > 1500 #=> fasle, this line is skipped. The processing of the last element generated by e1 is similar to that for the first element.
1 File is a subclass of IO (File < IO #=> true), so IO class methods such as foreach are often invoked on the File class (File.foreach...).