Convert DateTime to sequential day of the year

Question

I have a dataframe that contains a series of dates, eg:

0    2014-06-17
1    2014-05-05
2    2014-01-07
3    2014-06-29
4    2014-03-15
5    2014-06-06
7    2014-01-29

Now, I need a way to convert these dates to the sequential day of the year, eg

0    168
1    125
2    7
3    180
4    74
5    157
7    29

All the values are within the same year. The opposite problem has been asked many times - converting the sequential day of the year to a date, but I need to do the opposite. Is there an easy way to do this with Pandas? Thanks!

EDIT: Answered by piRSquared. Thank you!

Answer 1

Option 1
time-date-components
Link from @root
Use dt.dayofyear

df.iloc[:, 0].dt.dayofyear

0    168
1    125
2      7
3    180
4     74
5    157
7     29
Name: 1, dtype: int64

---

Option 2
strftime.org
Use dt.strftime('%-j')

df.iloc[:, 0].dt.strftime('%-j')


0    168
1    125
2      7
3    180
4     74
5    157
7     29
Name: 1, dtype: object

Answer 2

Yes, I did it. Please refer my below code.

Screen shot of my RESULT

Step 1: Make array of String datatype and add dates in string format.

Step 2: Use for loop because you have multiple dates.

Step 3: Convert String to Date format.

Step 4: Conver Date to LocalDate format.

Step 5: Use getDatOfYear() inbuilt function to get sequential day of the year.

package test;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.util.*;

public class ShubhamDateClass{
    public static void main(String[] args) {
        SimpleDateFormat formatter = new SimpleDateFormat("dd-MMM-yyyy");
        String[] dateForTest = {"17-JUN-2014","05-MAY-2014","07-JAN-2017","20-JUN-2014","15-MAR-2014", "6-JUN-2014", "29-JAN-2014"};
        for(int i=0;i<dateForTest.length;i++){
            try {

                Date date = formatter.parse(dateForTest[i]);
                System.out.print(formatter.format(date)+" --- ");
                LocalDate dateTest = Instant.ofEpochMilli(date.getTime()).atZone(ZoneId.systemDefault()).toLocalDate();
                int dayOfYear2 = dateTest.getDayOfYear();
                System.out.println(dayOfYear2);

            } catch (ParseException e) {
                e.printStackTrace();
            }

        }


    }
}