How to detect if dates are consecutive in Python?
11,411
Solution 1
Rather than rolling your own consecutive
function you can simply convert date objects to integers using the .toordinal()
method of datetime objects. The difference between the maximum and minimum value of the set of ordinal dates is one more than the length of the set:
from datetime import datetime
date_strs = ['07-06-2010', '06-24-2010', '07-05-2010', '06-25-2010']
# date_strs = ['02-29-2012', '02-28-2012', '03-01-2012']
# date_strs = ['01-01-2000']
dates = [datetime.strptime(d, "%m-%d-%Y") for d in date_strs]
date_ints = set([d.toordinal() for d in dates])
if len(date_ints) == 1:
print "unique"
elif max(date_ints) - min(date_ints) == len(date_ints) - 1:
print "consecutive"
else:
print "not consecutive"
Solution 2
Another version using the same logic as in my other answer.
from datetime import date, timedelta
# Definition 1: 1/1/14, 1/2/14, 1/2/14, 1/3/14 is consider consecutive
# Definition 2: 1/1/14, 1/2/14, 1/2/14, 1/3/14 is consider not consecutive
# datelist = [date(2014, 1, 1), date(2014, 1, 3),
# date(2013, 12, 31), date(2013, 12, 30)]
# datelist = [date(2014, 2, 19), date(2014, 2, 19), date(2014, 2, 20),
# date(2014, 2, 21), date(2014, 2, 22)]
datelist = [date(2014, 2, 19), date(2014, 2, 21),
date(2014, 2, 22), date(2014, 2, 20)]
datelist.sort()
previousdate = datelist[0]
for i in range(1, len(datelist)):
#if (datelist[i] - previousdate).days == 1 or (datelist[i] - previousdate).days == 0: # for Definition 1
if (datelist[i] - previousdate).days == 1: # for Definition 2
previousdate = datelist[i]
else:
previousdate = previousdate + timedelta(days=-1)
if datelist[-1] == previousdate:
print "dates are consecutive"
else:
print "dates are not consecutive"
Author by
Mike
Updated on June 24, 2022Comments
-
Mike almost 2 years
I have an access table with a 'Date' field. it has random dates for each record. I've built a script to append all the records into a list and then set the list to filter out only the unique values:
dateList = [] # cursor search through each record and append all records in the date # field to a python list for row in rows: dateList.append(row.getValue("DATE_OBSERVATION").strftime('%m-%d-%Y')) # Filter unique values to a set newList = list(set(dateList))
This returns (on my test table):
['07-06-2010', '06-24-2010', '07-05-2010', '06-25-2010']
Now that I have the unique values for the "DATE_OBSERVATION" field, I want to detect if:
- the dates are single (i.e. only one unique date is returned because that is the date in every record)
- if the dates are a range of dates (i.e. all of the dates fall into a consecutive range)
- if the dates are multiple dates, but are not in a range of consecutive dates
Any suggestions would be much appreciated! Mike