Datetime cannot parse certain literal months

I am currently working with date strings. It seems that not all dates can be interpreted using "datetime". E.g.:

datetime('05 Nov 2021','InputFormat','dd MMM yyyy','Locale','en_GB')

works fine, but

datetime('05 Sep 2021','InputFormat','dd MMM yyyy','Locale','en_GB')

throws:

Error using datetime

Unable to convert '05 Sep 2021' to datetime using the format 'dd MMM yyyy' and locale 'en_GB'.

I can not explain what is the matter with "Sep".

Answer 1

[Stephen23]

According to american logic, the british three-letter appreviation of September is "sept":

datetime('05 Nov 2021','InputFormat','dd MMM yyyy','Locale','en_GB')

ans = datetime
   05-Nov-2021

datetime('05 Sept 2021','InputFormat','dd MMM yyyy','Locale','en_GB')

ans = datetime
   05-Sep-2021

PS: to be fair, the DATETIME documentation does not state that abbreviations must be three letters (although I suspect that many english speakers would assume that it does), it actually states "MMM Month, abbreviated name", thus allowing any length abbreviation.

See: https://www.mathworks.com/help/matlab/ref/datetime.html#buhzxmk-1-Format

However the documentation does not list those abbreviations anywhere, nor the full months names or anything else, but it does link to the Unicode documentation, where if one spends enough time digging, one might find a reference to how dates are abbreviated in every supported language (I cound not find it).

[Thomas Cimiega]

Oh wow, thank you! Where can I find these definitions?

[Les Beckham]

Wow, indeed!

Without the Locale specification it errors with the 't' and works without it (in the US anyway)!

I would consider filing a bug report: report a bug

[Stephen23]

"Without the Locale specification it errors with the 't' and works without it (in the US anyway)!"

Because your locale is en_US, which apparently does not use the 't'.

"Where can I find these definitions?"

Here:

https://cldr.unicode.org/

Answer 2

[Jim Benjamin]

Hi everyone,

I have a similar problem: I like to convert the string array s(1) = "11-Mrz-2025 10:03:47" to datetime using

s1 = datetime(s(1), 'InputFormat', 'dd-MMM-yyyy hh:mm:ss', 'Locale', 'de_DE') and I get the error

Error using datetime (line 257)

Unable to convert '11-Mrz-2025 10:03:47' to datetime using the format 'dd-MMM-yyyy hh:mm:ss' and locale 'de_DE'.

I do not know why this Input Format is not working. Thank you

[Stephen23]

The 'de_DE' abbreviation of the third month is "März":

string(datetime(2025,3,11), 'MMM','de_DE')

ans = "März"

So your "Mrz" will not be matched. While we are here lets take a look at them all:

string(datetime(2025,1:12,11).', 'MMM','de_DE')

ans = 12x1 string array
    "Jan"
    "Feb"
    "März"
    "Apr"
    "Mai"
    "Juni"
    "Juli"
    "Aug"
    "Sept"
    "Okt"
    "Nov"
    "Dez"

As far as I can tell, the Unicode date names for German are defined here:

https://www.unicode.org/cldr/charts/46/verify/dates/de.html

Both "März" and "Mär" are defined, but not "Mrz". Lets try them both:

datetime('11März2025', 'Locale','de_DE','InputFormat','ddMMMyyyy')

ans = datetime
   11-Mar-2025

datetime('11Mär2025',  'Locale','de_DE','InputFormat','ddMMMyyyy')

Error using datetime (line 257)
Unable to convert '11Mär2025' to datetime using the format 'ddMMMyyyy' and locale 'de_DE'.