Multiple matches in hash table - ruby

Question

Learning Ruby (v. 2.5) in coursera.
Aim is to write on ruby simple parser, which will count what IP host is responsible for the most queries in the apache logs.
Apache logs:
87.99.82.183 - - [01/Feb/2018:18:50:06 +0000] "GET /favicon.ico HTTP/1.1" 404 504 "http://35.225.14.147/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.119 Safari/537.36"
87.99.82.183 - - [01/Feb/2018:18:50:52 +0000] "GET /secret.html HTTP/1.1" 404 505 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.119 Safari/537.36"
Ruby code:
class ApacheLogAnalyzer
def initialize
#total_hits_by_ip = {}
end
def analyze(file_name)
ip_regex = /^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}/
file = File.open(file_name , "r")
file.each_line do |line|
count_hits(ip_regex.match(line))
end
end
def count_hits(ip)
if ip
if #total_hits_by_ip[ip]
#total_hits_by_ip[ip] += 1
else
#total_hits_by_ip[ip] = 1
end
end
end
Result is following:
{#<MatchData "87.99.82.183">=>1, #<MatchData "87.99.82.183">=>1}
The result contains duplicates (it shoud contain one key "87.99.82.183" with value 2). Where could be the issue?

Answer 1

The result contains duplicates in your case because hash keys are different objects but with the same values. Look at this examples:
a = "hello world foo".match(/he/) # => #<MatchData "he">
b = "hello world bar".match(/he/) # => #<MatchData "he">
a == b # => false
You can replace the hash keys with just string for example to definitely avoid this:
class ApacheLogAnalyzer
def analyze(file_name)
File.open(file_name).each_line.inject(Hash.new(0)) do |result, line|
ip = line.split
hash[ip] += 1
result
end
end
end

Answer 2

Thank you for your comment. I found that using method to_s resolves the issue.
So improved code looks like this:
count_hits(ip_regex.match(line).to_s)