I analyzed features such as 19920203, 199203, 1992.02.03, 1992.02, 1992-02-03, 1992-02, and 920203 time formats, listing the regular expressions as follows:
Of course, this expression is not very perfect, can only do simple cutting, can not determine the legality of the date, about the date is legitimate, I still give Python time to deal with it.
According to the above regular expression, I write the Dateparser class as follows:
Import re
Import datetime
# ***************************************************
# *
# * Description: Non-standard date string processing
# * Author:wangye <pcn88 at hotmail Dot com>
# *
# ***************************************************
Class Dateparser (object):
def __init__ (self):
Self.pattern = Re.compile (
R ' ^ ((?: 19|20)? \d{2}) [-.]? ((?: [0-1]?| 1) [0-9]) [-.]? ((?: [0-3]?| [1-3]) [0-9])? $'
)
def __cutdate (self, date, flags):
y = date.year
m = Date.month if flags[1] Else 1
D = Date.day if flags[2] Else 1
return Datetime.date (Y, M, D)
def __mergeflags (self, FLAGS1, FLAGS2):
L = []
length = min (len (FLAGS1), Len (FLAGS2))
For I in range (0, length):
If Flags1[i] and Flags2[i]:
L.append (True)
Else
L.append (False)
return L
Def parse (self, strdate):
"""
Description: Time resolution method.
Parameters: Strdate The time string to parse, such as the target Time type DateTime (1992, 2, 3)
One of the following strings can be parsed:
19920203
199203
1992.02.03
1992.02
1992-02-03
1992-02
920203
return value:
If successful
Tuple (datetime, Flags), where DateTime represents the legal time that the conversion was completed.
Flags are flag bits, indicating the number of significant digits, such as 199202 the actual conversion of the year and month, the day did not,
However, this function returns the default of 1st, but flags will be represented as (true, true, False).
The preceding two true indicates that the year and month are converted, and the last false indicates that the day is not converted.
If you fail
Returns none.
"""
m = Self.pattern.match (strdate)
Flags = [False, False, false]
If M:
matches = List (m.groups ())
Flags = List (map (lambda x:true if x!=none else False, matches))
Results = List (map (lambda x:int (x) if x!=none else 1, matches))
# results = List (map (lambda x:1 if x==none else x, results))
If results[0]<100:
If results[0]>9:
Results[0] + + 1900
Else
Results[0] + + 2000
Return (Datetime.date (Results[0], results[1], results[2), flags)
Else
Return None
def convert (self, strdate, format):
"""
Description: The conversion date is the specified format.
Parameters: Strdate The strdate parameters of the same parse method.
Format Python time format identification, with Datetime.date.strftime format identity.
return value:
Returns a time string in the specified format format, if successful.
If it fails, returns none.
"""
Date = Self.parse (strdate)
If Date:
Date = Date[0]
return Datetime.date.strftime (date, format)
Else
Return None
def compare (self, strdate1, Strdate2):
"""
Description: Compares two dates.
Parameters: Strdate parameters of the same parse method as Strdate1 and Strdate2
return value:
Can be one of the following values
-4 strdate1 Invalid, strdate2 valid
-3 strdate1 valid, Strdate2 invalid
-2 strdate1 and Strdate2 invalid
-1 Strdate1 < Strdate2
0 strdate1 = Strdate2
1 strdate1 > Strdate2
"""
DATE1,FLAGS1 = Self.parse (strdate1)
DATE2,FLAGS2 = Self.parse (strdate2)
If date1 = = None and Date2!= None:
Return-4
If Date1!= none and Date2 = none:
Return-3
Elif Date1 = = None and Date2 = none:
Return-2
Flags = Self.__mergeflags (FLAGS1, FLAGS2)
Date1 = Self.__cutdate (date1, flags)
Date2 = Self.__cutdate (Date2, flags)
If Date1>date2:
Return 1
Elif Date1<date2:
Return-1
Else
return 0
