Date-time comparison in Ruby - ruby

I have one date, let's say '2010-12-20' of a flight departure, and two times, for instance, '23:30' and '02:15'.
The problem: I need to get datetimes (yyyy-MM-dd HH:mm:ss, for example, 2010-12-17 14:38:32) of both of these dates, but I don't know the day of the second time (it can be the same day as departure, or the next one).
I am looking for the best solution in Ruby on Rails. In PHP would just use string splitting multiple times, but I believe, that Rails as usually, has a much more elegant way.
So, here is my pseudo code, which I want to turn into Ruby:
depart_time = '23:30'
arrive_time = '02:15'
depart_date = '2010-12-20'
arrive_date = (arrive.hour < depart.hour and arrive.hour < 5) ? depart_date + 1 : depart_date
# Final results
depart = depart_date + ' ' + depart_time
arrive = arrive_date + ' ' + arrive_time
I want to find the best way to implement this in Ruby on Rails, instead of just playing with strings.

This is just pure Ruby, nothing to do with Rails:
require 'date'
depart_time = DateTime.strptime '23:30', '%H:%M'
arrive_time = DateTime.strptime '02:15', '%H:%M'
arrive_date = depart_date = Date.parse( '2010-12-20' )
arrive_date += 1 if arrive_time.hour < depart_time.hour and arrive_time.hour < 5
puts "#{depart_date} #{depart_time.strftime '%H:%M'}",
"#{arrive_date} #{arrive_time.strftime '%H:%M'}"
#=> 2010-12-20 23:30
#=> 2010-12-21 02:15

Related

Time Delta problem in Hackerrank not taking good answer / Python 3

The hackerrank challenge is in the following url: https://www.hackerrank.com/challenges/python-time-delta/problem
I got testcase 0 correct, but the website is saying that I have wrong answers for testcase 1 and 2, but in my pycharm, I copied the website expected output and compared with my output and they were exactly the same.
Please have a look at my code.
#!/bin/pyth
# Complete the time_delta function below.
from datetime import datetime
def time_delta(tmp1, tmp2):
dicto = {'Jan':1, 'Feb':2, 'Mar':3,
'Apr':4, 'May':5, 'Jun':6,
'Jul':7, 'Aug':8, 'Sep':9,
'Oct':10, 'Nov':11, 'Dec':12}
# extracting t1 from first timestamp without -xxxx
t1 = datetime(int(tmp1[2]), dicto[tmp1[1]], int(tmp1[0]), int(tmp1[3][:2]),int(tmp1[3][3:5]), int(tmp1[3][6:]))
# extracting t1 from second timestamp without -xxxx
t2 = datetime(int(tmp2[2]), dicto[tmp2[1]], int(tmp2[0]), int(tmp2[3][:2]), int(tmp2[3][3:5]), int(tmp2[3][6:]))
# converting -xxxx of timestamp 1
t1_utc = int(tmp1[4][:3])*3600 + int(tmp1[4][3:])*60
# converting -xxxx of timestamp 2
t2_utc = int(tmp2[4][:3])*3600 + int(tmp2[4][3:])*60
# absolute difference
return abs(int((t1-t2).total_seconds()-(t1_utc-t2_utc)))
if __name__ == '__main__':
# fptr = open(os.environ['OUTPUT_PATH'], 'w')
t = int(input())
for t_itr in range(t):
tmp1 = list(input().split(' '))[1:]
tmp2 = list(input().split(' '))[1:]
delta = time_delta(tmp1, tmp2)
print(delta)
t1_utc = int(tmp1[4][:3])*3600 + int(tmp1[4][3:])*60
For a time zone like +0715, you correctly add “7 hours of seconds” and “15 minutes of seconds”
For a timezone like -0715, you are adding “-7 hours of seconds” and “+15 minutes of seconds”, resulting in -6h45m, instead of -7h15m.
You need to either use the same “sign” for both parts, or apply the sign afterwards.

Subtract Time from CSV using Ruby

Hi I would like to subtract time from a CSV array using Ruby
time[0] is 12:12:00AM
time[1] is 12:12:01AM
Here is my code
time_converted = DateTime.parse(time)
difference = time_converted[1].to_i - time_converted[0].to_i
p difference
However, I got 0
p time[0].to_i gives me 12
is there a way to fix this?
You can use Time#strptime to define the format of the parsed string.
In your case the string is %I:%M:%S%p.
%I = 12 hour time
%M = minutes
%S = seconds
%p = AM/PM indicator
So to parse your example:
require 'time'
time = %w(12:12:00AM 12:12:01AM)
parsed_time = time.map { |t| Time.strptime(t, '%I:%M:%S%p').to_i }
parsed_time.last - parsed_time.first
=> 1
Use the Ruby DateTime class and parse your dates into objects of that class.

Join array of strings into 1 or more strings each within a certain char limit (+ prepend and append texts)

Let's say I have an array of Twitter account names:
string = %w[example1 example2 example3 example4 example5 example6 example7 example8 example9 example10 example11 example12 example13 example14 example15 example16 example17 example18 example19 example20]
And a prepend and append variable:
prepend = 'Check out these cool people: '
append = ' #FollowFriday'
How can I turn this into an array of as few strings as possible each with a maximum length of 140 characters, starting with the prepend text, ending with the append text, and in between the Twitter account names all starting with an #-sign and separated with a space. Like this:
tweets = ['Check out these cool people: #example1 #example2 #example3 #example4 #example5 #example6 #example7 #example8 #example9 #FollowFriday', 'Check out these cool people: #example10 #example11 #example12 #example13 #example14 #example15 #example16 #example17 #FollowFriday', 'Check out these cool people: #example18 #example19 #example20 #FollowFriday']
(The order of the accounts isn't important so theoretically you could try and find the best order to make the most use of the available space, but that's not required.)
Any suggestions? I'm thinking I should use the scan method, but haven't figured out the right way yet.
It's pretty easy using a bunch of loops, but I'm guessing that won't be necessary when using the right Ruby methods. Here's what I came up with so far:
# Create one long string of #usernames separated by a space
tmp = twitter_accounts.map!{|a| a.insert(0, '#')}.join(' ')
# alternative: tmp = '#' + twitter_accounts.join(' #')
# Number of characters left for mentioning the Twitter accounts
length = 140 - (prepend + append).length
# This method would split a string into multiple strings
# each with a maximum length of 'length' and it will only split on empty spaces (' ')
# ideally strip that space as well (although .map(&:strip) could be use too)
tweets = tmp.some_method(' ', length)
# Prepend and append
tweets.map!{|t| prepend + t + append}
P.S.
If anyone has a suggestion for a better title let me know. I had a difficult time summarizing my question.
The String rindex method has an optional parameter where you can specify where to start searching backwards in a string:
arr = %w[example1 example2 example3 example4 example5 example6 example7 example8 example9 example10 example11 example12 example13 example14 example15 example16 example17 example18 example19 example20]
str = arr.map{|name|"##{name}"}.join(' ')
prepend = 'Check out these cool people: '
append = ' #FollowFriday'
max_chars = 140 - prepend.size - append.size
until str.size <= max_chars do
p str.slice!(0, str.rindex(" ", max_chars))
str.lstrip! #get rid of the leading space
end
p str unless str.empty?
I'd make use of reduce for this:
string = %w[example1 example2 example3 example4 example5 example6 example7 example8 example9 example10 example11 example12 example13 example14 example15 example16 example17 example18 example19 example20]
prepend = 'Check out these cool people:'
append = '#FollowFriday'
# Extra -1 is for the space before `append`
max_content_length = 140 - prepend.length - append.length - 1
content_strings = string.reduce([""]) { |result, target|
result.push("") if result[-1].length + target.length + 2 > max_content_length
result[-1] += " ##{target}"
result
}
tweets = content_strings.map { |s| "#{prepend}#{s} #{append}" }
Which would yield:
"Check out these cool people: #example1 #example2 #example3 #example4 #example5 #example6 #example7 #example8 #example9 #FollowFriday"
"Check out these cool people: #example10 #example11 #example12 #example13 #example14 #example15 #example16 #example17 #FollowFriday"
"Check out these cool people: #example18 #example19 #example20 #FollowFriday"

Calculating the difference between durations with milliseconds in Ruby

TL;DR: I need to get the difference between HH:MM:SS.ms and HH:MM:SS.ms as HH:MM:SS:ms
What I need:
Here's a tricky one. I'm trying to calculate the difference between two timestamps such as the following:
In: 00:00:10.520
Out: 00:00:23.720
Should deliver:
Diff: 00:00:13.200
I thought I'd parse the times into actual Time objects and use the difference there. This works great in the previous case, and returns 00:0:13.200.
What doesn't work:
However, for some, this doesn't work right, as Ruby uses usec instead of msec:
In: 00:2:22.760
Out: 00:2:31.520
Diff: 00:0:8.999760
Obviously, the difference should be 00:00:8:760 and not 00:00:8.999760. I'm really tempted to just tdiff.usec.to_s.gsub('999','') ……
My code so far:
Here's my code so far (these are parsed from the input strings like "0:00:10:520").
tin_first, tin_second = ins.split(".")
tin_hours, tin_minutes, tin_seconds = tin_first.split(":")
tin_usec = tin_second * 1000
tin = Time.gm(0, 1, 1, tin_hours, tin_minutes, tin_seconds, tin_usec)
The same happens for tout. Then:
tdiff = Time.at(tout-tin)
For the output, I use:
"00:#{tdiff.min}:#{tdiff.sec}.#{tdiff.usec}"
Is there any faster way to do this? Remember, I just want to have the difference between two times. What am I missing?
I'm using Ruby 1.9.3p6 at the moment.
Using Time:
require 'time' # Needed for Time.parse
def time_diff(time1_str, time2_str)
t = Time.at( Time.parse(time2_str) - Time.parse(time1_str) )
(t - t.gmt_offset).strftime("%H:%M:%S.%L")
end
out_time = "00:00:24.240"
in_time = "00:00:14.520"
p time_diff(in_time, out_time)
#=> "00:00:09.720"
Here's a solution that doesn't rely on Time:
def slhck_diff( t1, t2 )
ms_to_time( time_as_ms(t2) - time_as_ms(t1) )
end
# Converts "00:2:22.760" to 142760
def time_as_ms( time_str )
re = /(\d+):(\d+):(\d+)(?:\.(\d+))?/
parts = time_str.match(re).to_a.map(&:to_i)
parts[4]+(parts[3]+(parts[2]+parts[1]*60)*60)*1000
end
# Converts 142760 to "00:02:22.760"
def ms_to_time(ms)
m = ms.floor / 60000
"%02i:%02i:%06.3f" % [ m/60, m%60, ms/1000.0 % 60 ]
end
t1 = "00:00:10.520"
t2 = "01:00:23.720"
p slhck_diff(t1,t2)
#=> "01:00:13.200"
t1 = "00:2:22.760"
t2 = "00:2:31.520"
p slhck_diff(t1,t2)
#=> "00:00:08.760"
I figured the following could work:
out_time = "00:00:24.240"
in_time = "00:00:14.520"
diff = Time.parse(out_time) - Time.parse(in_time)
Time.at(diff).strftime("%H:%M:%S.%L")
# => "01:00:09.720"
It does print 01 for the hour, which I don't really understand.
In the meantime, I used:
Time.at(diff).strftime("00:%M:%S.%L")
# => "00:00:09.720"
Any answer that does this better will get an upvote or the accept, of course.
in_time = "00:02:22.760"
out_time = "00:02:31.520"
diff = (Time.parse(out_time) - Time.parse(in_time))*1000
puts diff
OUTPUT:
8760.0 millliseconds
Time.parse(out_time) - Time.parse(in_time) gives the result in seconds so multiplied by 1000 to convert into milliseconds.

Simplest way to display each hour of the day in Ruby

I have a calendar screen where I want to display the hours of the day like this:
12:00am
1:00am
2:00am
..
4:00pm
5:00pm
etc.
Being a total Ruby noob, I was wondering if anyone could help me figure out the simplest way to display this.
#!/usr/bin/env ruby
# without using actual `Date` objects ...
p ["12:00am"] + (1..11).map {|h| "#{h}:00am"}.to_a +
["12:00pm"] + (1..11).map {|h| "#{h}:00pm"}.to_a
["12:00am", "1:00am", "2:00am", "3:00am", "4:00am", "5:00am", "6:00am",
"7:00am", "8:00am", "9:00am", "10:00am", "11:00am", "12:00pm", "1:00pm",
"2:00pm", "3:00pm", "4:00pm", "5:00pm", "6:00pm", "7:00pm", "8:00pm",
"9:00pm", "10:00pm", "11:00pm"]
Or using actual DateTime objects and %I:%M%p as format:
#!/usr/bin/env ruby
require "Date"
for hour in 0..23 do
d = DateTime.new(2010, 1, 1, hour, 0, 0)
p d.strftime("%I:%M%p")
end
Which would print:
"12:00AM"
"01:00AM"
"02:00AM"
"03:00AM"
"04:00AM"
"05:00AM"
"06:00AM"
"07:00AM"
"08:00AM"
"09:00AM"
"10:00AM"
"11:00AM"
"12:00PM"
"01:00PM"
"02:00PM"
"03:00PM"
"04:00PM"
"05:00PM"
"06:00PM"
"07:00PM"
"08:00PM"
"09:00PM"
"10:00PM"
"11:00PM"
You could generate these like this:
array = ['12:00am'] + (1..11).map {|h| "#{h}:00am"} + ['12:00pm'] + (1..11).map {|h| "#{h}:00pm"}
or simply write out the array (this is more efficient):
array = ["12:00am", "1:00am", "2:00am", "3:00am", "4:00am", "5:00am", "6:00am", "7:00am", "8:00am", "9:00am", "10:00am", "11:00am", "12:00pm", "1:00pm", "2:00pm", "3:00pm", "4:00pm", "5:00pm", "6:00pm", "7:00pm", "8:00pm", "9:00pm", "10:00pm", "11:00pm"]
You can then print these however you want, eg.
array.each do |el|
puts el
end

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