Calculating Total Job Experience - algorithm

Question

I need to calculate the total job experience as year value. Users add experiences with starting and ending dates to their resumes, just like Linkedin. But there is no any certain pattern. For instance;
A user may have a resume like that;
Experience 2
08.2012 - 01.2015
Experience 1
01.2011 - 01.2013
The user started their second experience while the first hasn't finished yet. So resumes may have many overlapping experiences. Overlapping also may occur between more than 2. So I need to consider many cases.
I tried to visualise the experience and year relationship for you.
I just need to develop an algorithm covering all the cases for this issue.

Answer 1

Sort by start date
start at the beginning and accumulate overlapping experiences (i.e. treat as one)
e.g. (Jan 2012, Jan 2015), (Jan 2014, Dec 2016) overlap, so we treat it as a single experience
This "super experience" begins at the start of the first, and ends at the end of the last; (Jan 2012, Dec 2016)
This is assuming that there can be gaps in experience, so we don't want to treat the entire history as one long "super experience"

Answer 2

I just did this
Sort the experiences by Begin Date.
Use 2 variables, that represent the begin of work and the end called Begin
and End.
If end and begin are empty it means that is the first date, we filled with the first experience, and we calculate the month count between the begin and end of this experience and and then this months count add to our months accumulator.
if the end and begin date of next experience is not between our begin and end variables, we calculate the months count from the experience and then add it to our accumulator.
If the begin date of next experience is between our begin and end variables, we calculate the months count between our end date as begin and the experience end date as end, and then that difference add to our months accumulator.
as you can see every time we set our new end if the experience end is greater than ours.
at the end we get the months, if you divide by 12 you get the years exactly you can round it if you want
NOTE: I Mapped the experiences, if not have End it means that is equivalent to NOW
you can see all the code below
function monthDiff(d1, d2) {
var m = (d1.getFullYear() - d2.getFullYear()) * 12 +
(d1.getMonth() - d2.getMonth());
if (d1.getDate() < d2.getDate()) --m;
return m;
}
function dateCheck(from, to, check) {
var fDate, lDate, cDate;
fDate = Date.parse(from);
lDate = Date.parse(to);
cDate = Date.parse(check);
if (cDate <= lDate && cDate >= fDate) {
return true;
}
return false;
}
function calculateYearsOfExperience(experiences) {
if (!experiences) return 0;
let months = 0;
let now = new Date();
let sorted = experiences
.sort((a, b) => {
return new Date(a.begin) - new Date(b.begin);
})
.map(experience => {
if (!experience.end) experience.end = now;
return { begin: experience.begin, end: experience.end };
});
let begin;
let end;
for (var i in sorted) {
let dif = 0;
if (!end && !begin) {
dif = monthDiff(sorted[i].begin, sorted[i].end);
begin = sorted[i].begin;
end = sorted[i].end;
} else if (
!dateCheck(begin, end, sorted[i].begin) &&
!dateCheck(begin, end, sorted[i].end)
) {
dif = monthDiff(sorted[i].begin, sorted[i].end);
end = sorted[i].end;
} else if (dateCheck(begin, end, sorted[i].begin)) {
dif = monthDiff(end, sorted[i].end);
end = sorted[i].end;
}
months += dif;
}
return months / 12;
}

Answer 3

experiences = [
# (start date, end date),
(date(2012, 8, 1), date(2015, 1, 30)),
(date(2011, 1, 1), date(2013, 1, 30))
]
print(sum((end_date - start_date).days/365 for start_date, end_date in experiences))

Answer 4

Create an array full of 0. Element range: Start would be the very first hire date, last would be current date / last working date. For every year you have 12 elements that can be 0/1. After filling in the array count the elements that have the value 1. If you need to take into account the overlapping then ignore the 0/1 part and give +1 for every month worked.

Answer 5

This is c# code, but you'll get the steps in algorithm. It returns total number of months which you can convert into year and month format.
var sortedList = expList
.OrderBy(a => a.start_year)
.ThenBy(a => a.start_month)
.ThenBy(a => a.end_year)
.ThenBy(a => a.end_month)
.ToList();
int totalMonths = 0;
int totalDays = 0;
DateTime? prevEndDate = null;
foreach (var exp in sortedList)
{
if(exp.start_month != null && exp.start_year != null)
{
var startDate = new DateTime((int)exp.start_year, (int)exp.start_month, 1);
var endDate = (bool)exp.is_present ?
DateTime.Now :
new DateTime((int)exp.end_year, (int)exp.end_month, 1);
if (prevEndDate != null && prevEndDate > startDate)
{
startDate = (DateTime)prevEndDate;
}
var timespan = endDate.Subtract(startDate);
var tempdate = DateTime.MinValue + timespan;
totalMonths = totalMonths + (tempdate.Year - 1) * 12 + tempdate.Month - 1;
totalDays = totalDays + tempdate.Day - 1;
prevEndDate = endDate;
}
}
if (totalDays > 0)
{
totalMonths = totalMonths + 1;
}

Answer 6

public static function YearCalculation($id=null) {
if($id=="")
$employee_id=#Auth::guard('web_employee')->user()->id;
else
$employee_id=$id;
$employee_exp = Experience::where('employee_id',$employee_id)->orderBy("experience_from","ASC")->get();
//print_r($employee_exp ); exit;
$years = 0;
$months = 0;
$days = 0;
$sum=0;
$lastfromdate=0;
$last_endDate=0;
if(#$employee_exp!=null){
foreach(#$employee_exp as $experience){
$fdate = #$experience->experience_from;
if($experience->is_current==0){
$tdate = #$experience->experience_to;
}else{
$tdate = date("Y-m-d");
}
if($last_endDate != date("Y-m-d") ){
if( $fdate < $last_endDate ){
$start_date1 = strtotime($last_endDate);
$end_date1 = strtotime($tdate);
$interval1 = ($end_date1 - $start_date1)/60/60/24;
$sum +=$interval1;
}
else{
$start_date2 = strtotime($fdate);
$end_date2 = strtotime($tdate);
$interval2 = ($end_date2 - $start_date2)/60/60/24;
$sum +=$interval2;
}
if($last_endDate < $tdate){
$last_endDate=$tdate;
}
}
}
$years = ($sum / 365) ;
$years = floor($years);
$month = ($sum % 365) / 30.4166;
$month = floor($month);
$days = ($sum % 365) % 30.4166;
//$total=date_diff(0,$tmstamp);
//$total_year=$years.' years, ' .$month.' months and '.$days.($days==1?' day':' days');
$total_year=($years==0?'':($years==1?$years.' year':$years.' years and ')) .($month==0?'':($month==1?$month.($days>1?'+':'').' month':$month.($days>1?'+':'').' months'));
return $total_year;
}
}