Stripping time from a string to calculate elapsed time

Processing.py
1

Hello,
I would like to calculate elapsed time based on start and end times (extracted from an XML file)
startDate=“2016-11-16 09:26:33 +1000” endDate="2016-11-16 09:26:33
As the times are embedded in a string(see above),
I think

  • firstly, I need to extract the start and end times into hour, minute, seconds variables from the string
    for example., hour from 12th position, length 2 (please help with Python syntax to do this, thanks)
  • then convert hour, minute & second into seconds
  • then calculate difference in seconds

Regards, Paul

1 Like
2

Docs.Python.org/2.7/library/datetime.html#module-datetime
Docs.Python.org/2.7/library/datetime.html#strftime-strptime-behavior

from datetime import datetime

a = datetime(2016, 11, 16, 9, 26, 33, 1000)
b = datetime.today()

print a, ENTER, b, ENTER, b - a
exit()
2 Likes
3

I’m not sure what the “+1000” part is for? Anyhow, here’s some code that should do it for you:

from datetime import datetime

startDate = '2016-11-16 09:26:33 +1000'
endDate = '2016-11-16 09:26:33'

# strip-off the +1000 part
startPlus = startDate[startDate.index('+')+1:] # 1000
startDate = startDate[:-len(startPlus)-2] # 2016-11-16 09:26:33

# convert start date to datetime format
startDate = datetime.strptime(startDate, '%Y-%m-%d %H:%M:%S')

# convert end date to datetime format
endDate = datetime.strptime(endDate, '%Y-%m-%d %H:%M:%S')

# difference is zero seconds, but you can fiddle with the initial variables
print( (startDate-endDate).total_seconds() )

I’ve stripped-off the +1000 part, but stored the 1000 in the startPlus variable if you need it.

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4

Thank you for your replies with coding plus attachments (extra info.)
@tabreturn @GoToLoop
all very useful and contribute to the progress of my program.

1 Like
5

@GoToLoop @tabreturn
Thank you for the above code (a while ago) for using the datetime routines, working well for my sketches written using Processing Python mode, .
Instead of Python mode, I now want to do the same coding in Processing (version 3.5.4) but unsure of the syntax to import datetime and subsequent calls to strip dates, as above.
For example, when I replaced ‘from datetime import datetime’ in Python mode
with ‘import datetime’ or ‘import datetime.*’ in Processing mode,
I get an error message: The package “datetime” does not exist. You might be missing a library…no Library found for datetime

Any tips and sample code in Processing appreciated, thanks.

6

Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/time/LocalDateTime.html
Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/time/Duration.html

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7

To add to @GoToLoop’s response –

The datetime is a Python module. You’ll have to import the necessary java modules, something like this:

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;

LocalDate dateA = LocalDate.parse("2011-01-01");
LocalDate dateB = LocalDate.parse("2021-02-01");
print(ChronoUnit.DAYS.between(dateA, dateB));
2 Likes
8

Thanks for above tips but need a bit more help.
So I am trying to calculate using Processing code, the difference in seconds between two date-time stamps (format "yyyymmdd hh:mm:ss).

For example, “2016-01-01 00:01:02” minus “2015-12-31 23:59:10” should return 112 seconds.
Much thanks in advance for further tips.

9

@tabreturn and @GoToLoop, belated thanks to your suggestions a while ago. So what I did (for those who may find it useful) to calculate difference in seconds between two date-time stamps (using hints/suggestions above by @tabreturn)

  1. import java.time.LocalDateTime;
    import java.time.temporal.ChronoUnit;
  2. convert strings “yyyy-mm-dd hh:mm:ss” to “yyyy-mm-ddThh:mm:ss” (by concatenating strings “yyyy-mm-dd” + “T” + “hh:mm:ss”)
  3. parse these 2 strings using LocalDateTime.parse (converted_string)
  4. calculate the difference in seconds between the parsed date-time stamps using ChronoUnit.SECONDS.between(parsed date-time 1 - parsed date-time 2)
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