Parsing files (ics/ icalendar) using Python

Question

I have a .ics file in the following format. What is the best way to parse it? I need to retrieve the Summary, Description, and Time for each of the entries.

Answer 1

You could probably also use the vobject module for this: http://pypi.python.org/pypi/vobject

If you have a sample.ics file you can read it's contents like, so:

# read the data from the file
data = open("sample.ics").read()

# parse the top-level event with vobject
cal = vobject.readOne(data)

# Get Summary
print 'Summary: ', cal.vevent.summary.valueRepr()
# Get Description
print 'Description: ', cal.vevent.description.valueRepr()

# Get Time
print 'Time (as a datetime object): ', cal.vevent.dtstart.value
print 'Time (as a string): ', cal.vevent.dtstart.valueRepr()

Answer 2

New to python; the above comments were very helpful so wanted to post a more complete sample.

# ics to csv example
# dependency: https://pypi.org/project/vobject/

import vobject
import csv

with open('sample.csv', mode='w') as csv_out:
    csv_writer = csv.writer(csv_out, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL)
    csv_writer.writerow(['WHAT', 'WHO', 'FROM', 'TO', 'DESCRIPTION'])

    # read the data from the file
    data = open("sample.ics").read()

    # iterate through the contents
    for cal in vobject.readComponents(data):
        for component in cal.components():
            if component.name == "VEVENT":
                # write to csv
                csv_writer.writerow([component.summary.valueRepr(),component.attendee.valueRepr(),component.dtstart.valueRepr(),component.dtend.valueRepr(),component.description.valueRepr()])

Answer 3

Four years later and understanding ICS format a bit better, if those were the only fields I needed, I'd just use the native string methods:

import io

# Probably not a valid .ics file, but we don't really care for the example
# it works fine regardless
file = io.StringIO('''
BEGIN:VCALENDAR
X-LOTUS-CHARSET:UTF-8
VERSION:2.0
DESCRIPTION:Emails\nDarlene\n Murphy\nDr. Ferri\n

SUMMARY:smart energy management
LOCATION:8778/92050462
DTSTART;TZID="India":20100629T110000
DTEND;TZID="India":20100629T120000
TRANSP:OPAQUE
DTSTAMP:20100713T071037Z
CLASS:PUBLIC
SUMMARY:meeting
UID:6011DDDD659E49D765257751001D2B4B-Lotus_Notes_Generated
X-LOTUS-UPDATE-SEQ:1
X-LOTUS-UPDATE-WISL:$S:1;$L:1;$B:1;$R:1;$E:1;$W:1;$O:1;$M:1
X-LOTUS-NOTESVERSION:2
X-LOTUS-APPTTYPE:0
X-LOTUS-CHILD_UID:6011DDDD659E49D765257751001D2B4B
END:VEVENT
'''.strip())

parsing = False
for line in file:
    field, _, data = line.partition(':')
    if field in ('SUMMARY', 'DESCRIPTION', 'DTSTAMP'):
        parsing = True
        print(field)
        print('\t'+'\n\t'.join(data.split('\n')))
    elif parsing and not data:
        print('\t'+'\n\t'.join(field.split('\n')))
    else:
        parsing = False

Storing the data and parsing the datetime is left as an exercise for the reader (it's always UTC)

old answer below

---

You could use a regex:

import re
text = #your text
print(re.search("SUMMARY:.*?:", text, re.DOTALL).group())
print(re.search("DESCRIPTION:.*?:", text, re.DOTALL).group())
print(re.search("DTSTAMP:.*:?", text, re.DOTALL).group())

I'm sure it may be possible to skip the first and last words, I'm just not sure how to do it with regex. You could do it this way though:

print(' '.join(re.search("SUMMARY:.*?:", text, re.DOTALL).group().replace(':', ' ').split()[1:-1])

Answer 4

The icalendar package looks nice.

For instance, to write a file:

from icalendar import Calendar, Event
from datetime import datetime
from pytz import UTC # timezone

cal = Calendar()
cal.add('prodid', '-//My calendar product//mxm.dk//')
cal.add('version', '2.0')

event = Event()
event.add('summary', 'Python meeting about calendaring')
event.add('dtstart', datetime(2005,4,4,8,0,0,tzinfo=UTC))
event.add('dtend', datetime(2005,4,4,10,0,0,tzinfo=UTC))
event.add('dtstamp', datetime(2005,4,4,0,10,0,tzinfo=UTC))
event['uid'] = '20050115T101010/27346262376@mxm.dk'
event.add('priority', 5)

cal.add_component(event)

f = open('example.ics', 'wb')
f.write(cal.to_ical())
f.close()

Tadaaa, you get this file:

BEGIN:VCALENDAR
PRODID:-//My calendar product//mxm.dk//
VERSION:2.0
BEGIN:VEVENT
DTEND;VALUE=DATE:20050404T100000Z
DTSTAMP;VALUE=DATE:20050404T001000Z
DTSTART;VALUE=DATE:20050404T080000Z
PRIORITY:5
SUMMARY:Python meeting about calendaring
UID:20050115T101010/27346262376@mxm.dk
END:VEVENT
END:VCALENDAR

But what lies in this file?

g = open('example.ics','rb')
gcal = Calendar.from_ical(g.read())
for component in gcal.walk():
    print component.name
g.close()

You can see it easily:

>>> 
VCALENDAR
VEVENT
>>> 

What about parsing the data about the events:

g = open('example.ics','rb')
gcal = Calendar.from_ical(g.read())
for component in gcal.walk():
    if component.name == "VEVENT":
        print(component.get('summary'))
        print(component.get('dtstart'))
        print(component.get('dtend'))
        print(component.get('dtstamp'))
g.close()

Now you get:

>>> 
Python meeting about calendaring
20050404T080000Z
20050404T100000Z
20050404T001000Z
>>> 

Answer 5

I'd parse line by line and do a search for your terms, then get the index and extract that and X number of characters further (however many you think you'll need). Then parse that much smaller string to get it to be what you need.