remove too close time elements from a json array - arrays

Question

I am having an array of json object which contain timing and data.
Basically, each element, contain timing, id and user as below
[
{
"id": "abc",
"ts": "2017-08-17T20:42:12.557229",
"userid": "seb"
},
{
"id": "def",
"ts": "2017-08-17T20:42:52.724773",
"userid": "seb"
},
{
"id": "ghi",
"ts": "2017-08-17T20:42:53.724773",
"userid": "matt"
},
{
"id": "jkl",
"ts": "2017-08-17T20:44:50.557229",
"userid": "seb"
},
{
"id": "mno",
"ts": "2017-08-17T20:44:51.724773",
"userid": "seb"
},
{
"id": "pqr",
"ts": "2017-08-17T20:50:52.724773",
"userid": "seb"
}
]
My goal is to remove object too close to each other if the userid is the same. if the time difference is below 2 sec, we remove the element.
From the list, I should get the list
[
{
"id": "abc",
"ts": "2017-08-17T20:42:12.557229",
"userid": "seb"
},
{
"id": "def",
"ts": "2017-08-17T20:42:52.724773",
"userid": "seb"
},
{
"id": "ghi",
"ts": "2017-08-17T20:42:53.724773",
"userid": "matt"
},
{
"id": "pqr",
"ts": "2017-08-17T20:50:52.724773",
"userid": "seb"
}
]
even if the 2 objects for user matt and seb are too close to each other below 2seconds, we have to keep the element as it's not the same user
"ts": "2017-08-17T20:42:52.724773" for seb
and
"ts": "2017-08-17T20:42:53.724773" for matt
Any idea how to code it in Ruby ? I always compared the element n to the n-1 and delete the n-1 if needed

Answer 1

require 'time'
result = []
timestamps = {}
data.each do |item|
ts = timestamps[item['userid']]
if ts.nil? or Time.parse(item['ts']) - Time.parse(ts) > 2
result.push(item)
timestamps[item['userid']] = item['ts']
end
end
puts result

Answer 2

What about the code below?
It changes the order of the records, but you could re-sort them if needed.
require 'date'
def time_elapsed_in_seconds(start_time, end_time)
((end_time - start_time) * 24 * 60 * 60).to_i
end
def too_close?(first_time, second_time, threshold = 2)
time_elapsed_in_seconds(first_time, second_time) < threshold
end
def datetimes(a, b)
return [DateTime.parse(a), DateTime.parse(b)]
end
def should_reject_record?(record, next_record)
datetimes = datetimes(record[:ts], next_record[:ts])
record[:userid] == next_record[:userid] && too_close?(*datetimes)
end
def filter_records(records)
sorted = records.sort_by{|record| [record[:userid], record[:ts]] }
sorted.select.with_index do |record, index|
previous_record = sorted[index-1]
record == sorted.first || !should_reject_record?(previous_record, record)
end
end
records = [
{
"id": "abc",
"ts": "2017-08-17T20:42:12.557229",
"userid": "seb"
},
{
"id": "def",
"ts": "2017-08-17T20:42:52.724773",
"userid": "seb"
},
{
"id": "ghi",
"ts": "2017-08-17T20:42:53.724773",
"userid": "matt"
},
{
"id": "jkl",
"ts": "2017-08-17T20:44:50.557229",
"userid": "seb"
},
{
"id": "mno",
"ts": "2017-08-17T20:44:51.724773",
"userid": "seb"
},
{
"id": "pqr",
"ts": "2017-08-17T20:50:52.724773",
"userid": "seb"
}
]
puts filter_records(records)