In a previous post I discussed the problem of converting time strings to time numbers. I have now extracted this functionality from our main application, rewritten it, and made it an open source project, imaginatively, but prematurely, named Text2Date. Text2Date uses a modified version of the Dyalog format pattern that is the left argument of 1200⌶.

One useful recent, simplifying, insight gained in the process of rewriting is that differentiating between undelimited and delimited fixed-width formats strings is useful. Delimited fixed-width time strings must line up - the elements must be in the exact positions specified in the format string. Undelimited format strings do not require that the time strings line up. For example, the format string MMDDYY can easily process the character matrix:

123124
10125
  72476
011523

yielding four dates:

      'MMDDYY' Text2Date '123124' '10125' '  72476   ' '011523'
20241231 20250101 19760724 20230115

When there are no delimiters, we don't need to worry about where an element starts or ends. The time string is just a text representation of a date time packed into an integer. A missing leading zero is no problem. Leading and trailing blanks are no problem. Data in this format shows up all the time in Excel and CSV files out in the wild.

In the case of undelimited formats, there is also no need that the input are time strings, numeric is just as good, if not better. Text2Date is now misnamed, as this works:

      'MMDDYY' Text2Date 123124 10125 72476 011523
20241231 20250101 19760724 20230115

Three special format strings are also accepted: Excel or Excel1900, and Excel1904, which also work on text or numeric input:

      'Excel' Text2Date 35000 37125 41256
19951028 20010822 20121213
      'Excel' Text2Date '35000' '37125' '41256'
19951028 20010822 20121213