Suggestion: Date formats without punctuation

[Richard Ristow]

It's fairly common for data to come in with dates represented as
unpunctuated strings, or as numbers whose decimal representation is
such a string:
'20080211' or '02112008' for today, 11-FEB-2008.

Just recently, a couple of posters have asked how to convert these to
SPSS dates; answers have been posted.

I wouldn't recommend these representations; but since they occur, it
would be useful to have SPSS date formats for them:


Format  Description   Min w   General   Examples
type                          form    28-OCT-1990 11-FEB-2008
-------------------------------------------------------------
YMDx    Unpunctuated  6       yymmdd    901028      080211
         YrMnthDay     8       yyyymmdd  19901028    20080211
-------------------------------------------------------------
MDYx    Unpunctuated  6       mmddyy    102890      021108
         MnthDayYear   8       mmddyyyy  10281990    02112008
-------------------------------------------------------------

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[Peck, Jon]

I would like to see a lot of additional date/time formats available in SPSS: there is an infinite variety of ways in which dates are represented, including many national variations.  But that way lies madness.  There will always be another format.

As an alternative, a pattern language for describing dates gives a lot more flexibility.  And we have a pattern language available in one of the Python supplementary modules available on Developer Central (www.spss.com/devcentral): extendedTransforms.py in the function strtodatetime.

Here, from the docstring, are the pattern symbols.  You can compose a description from these such as
"%y%m%d"
to describe the pattern in a string and create an SPSS date value.  The function datetimetostr can be used to go the reverse direction.

    %a Locale's abbreviated weekday name.
    %A Locale's full weekday name.
    %b Locale's abbreviated month name.
    %B Locale's full month name.
    %c Locale's appropriate date and time representation.
    %d Day of the month as a decimal number [01,31].
    %H Hour (24-hour clock) as a decimal number [00,23].
    %I Hour (12-hour clock) as a decimal number [01,12].
    %j Day of the year as a decimal number [001,366].
    %m Month as a decimal number [01,12].
    %M Minute as a decimal number [00,59].
    %p Locale's equivalent of either AM or PM. (1)
    %S Second as a decimal number [00,61]. (2)
    %U Week number of the year (Sunday as the first day of the week) as a decimal number [00,53].
    All days in a new year preceding the first Sunday are considered to be in week 0. (3)
    %w Weekday as a decimal number [0(Sunday),6].
    %W Week number of the year (Monday as the first day of the week) as a decimal number [00,53].
    All days in a new year preceding the first Monday are considered to be in week 0. (3)
    %x Locale's appropriate date representation.
    %X Locale's appropriate time representation.
    %y Year without century as a decimal number [00,99].
    %Y Year with century as a decimal number.
    %Z Time zone name (no characters if no time zone exists).
    %% A literal "%" character.

    (1)When used with the strptime() function, the %p directive only affects the output hour field if the %I directive is used to parse the hour.
    (2)The range really is 0 to 61; this accounts for leap seconds and the (very rare) double leap seconds.
    (3)When used with the strptime() function, %U and %W are only used in calculations when the day of the week and the year are specified.

HTH,
Jon Peck

-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Richard Ristow
Sent: Sunday, February 10, 2008 11:48 PM
To: [hidden email]
Subject: [SPSSX-L] Suggestion: Date formats without punctuation

It's fairly common for data to come in with dates represented as
unpunctuated strings, or as numbers whose decimal representation is
such a string:
'20080211' or '02112008' for today, 11-FEB-2008.

Just recently, a couple of posters have asked how to convert these to
SPSS dates; answers have been posted.

I wouldn't recommend these representations; but since they occur, it
would be useful to have SPSS date formats for them:


Format  Description   Min w   General   Examples
type                          form    28-OCT-1990 11-FEB-2008
-------------------------------------------------------------
YMDx    Unpunctuated  6       yymmdd    901028      080211
         YrMnthDay     8       yyyymmdd  19901028    20080211
-------------------------------------------------------------
MDYx    Unpunctuated  6       mmddyy    102890      021108
         MnthDayYear   8       mmddyyyy  10281990    02112008
-------------------------------------------------------------

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