计算经过时间

Question

I have a text file that always looks like this:

977-183 BCA-0055 2014-02-19 10:08:13.61
977-001 BCA-0058 2014-02-19 10:29:08.18
977-013 BCA-0064 2014-02-19 10:28:35.73
977-129 BCA-0079 2014-02-19 10:15:45.24

These are generators. My goal is to add an additional column showing the total hours they have been running until now, which is when the I run the script. I am brand new to python and am stuck. I have figured out how to make a datetime object? for the now time. I had hoped to use this in my calculations (timedelta?) but have not been able to create a datetime for the times in the text file to move on. I have tried some things and read quite a bit but no luck, here is code showing my latest attempt:

import datetime
import time

i = datetime.datetime.now()
print i

# this is what the raw data looks like
# 977-183 BCA-0055 2014-02-19 10:08:13.61

raw0 = open("genParse.txt", "r") # text file containing date and time
fin0 = open("elapsed_time.txt", "w") # will contain elapsed times

for line in raw0:
    if '977-' in line:
       line = line.split() 
       date = line[2]
       time = line[3]
             # create datetime object for use in elapsed time calculations
             #tnew = datetime.datetime(date[0:4], date[5:7], date[8:10])
             print date[0:4], date[5:7], date[8:10]

Answer 1

Use datetime.datetime.strptime() to parse your strings to datetime.datetime() objects:

dt = datetime.datetime.strptime(date + ' ' + time, '%Y-%m-%d %H:%M:%S.%f')

Now you can calculate the time elapsed:

elapsed = now - dt

which is a timedelta object.

Demo:

>>> import datetime
>>> now = datetime.datetime.now()
>>> date = '2014-02-19'
>>> time = '10:08:13.61'
>>> dt = datetime.datetime.strptime(date + ' ' + time, '%Y-%m-%d %H:%M:%S.%f')
>>> dt
datetime.datetime(2014, 2, 19, 10, 8, 13, 610000)
>>> now - dt
datetime.timedelta(6, 30419, 490913)

The resulting timedelta object here has a value of 6 days, 30419 seconds and 490913 microseconds. How you format that to a string is up to you.

Answer 2

If you want to get the difference between the entry and when the script is executed:

from datetime import datetime

raw0 = open("genParse.txt", "r") # text file containing date and time
fin0 = open("elapsed_time.txt", "w") # will contain elapsed times

for line in raw0:
    if '977-' in line:
        line = line.split() 
        dts = '%s %s' % (line[2], line[3])
        now = datatime.now()
        fmt = '%Y-%m-%d %H:%M:%S.%f'
        time_diff = datetime.strptime(now, FMT) - datetime.strptime(dts, FMT)

You can obviously do whatever you want with time_diff , which is a timedelta object. Print, to file, etc. This is just expanding on the code you have already written. Like always with Python, there are many ways to accomplish the same goal.