How to convert a string into a date or datenum?

I have a column, about [4000 x 1] with the format 'yyyymmddHH'. Yes, all the numbers are together.

And i need to get a date, or a datenum from that, but i cant, since functions like datetime need the numbers separated.

Anyone know how to get arround this?

Thank you.

Answer 1

[Stephen23]

"... but i cant, since functions like datetime need the numbers separated."

I don't see that restriction mentioned anywhere in the DATETIME documentation.

S = ["2021061701";"2021010100";"1913061423"]

S = 3×1 string array
    "2021061701"
    "2021010100"
    "1913061423"

D = datetime(S, 'InputFormat','yyyyMMddHH')

D = 3×1 datetime array
   17-Jun-2021 01:00:00
   01-Jan-2021 00:00:00
   14-Jun-1913 23:00:00

[Bruno Carvalho]

Mine gives me error.

"Error using datetime (line 597)

Numeric input data must be a matrix with three or six columns, or else three, six, or seven separate numeric

arrays. You can also create datetimes from a single numeric array using the 'ConvertFrom' parameter."

[Stephen23]

If the data are stored as numeric where the digits of one value represent date units (ugh, ugh, ugh, a true abomination and crime against nature) then you can convert to string first:

VeryBadlyStoredDates = [2021061701;2021010100;1913061423] % should be illegal

VeryBadlyStoredDates = 3×1

2021061701 2021010100 1913061423

DT = datetime(string(VeryBadlyStoredDates), 'InputFormat','yyyyMMddHH')

DT = 3×1 datetime array
   17-Jun-2021 01:00:00
   01-Jan-2021 00:00:00
   14-Jun-1913 23:00:00

Even better: create or import that data properly as datetime, rather than as numeric.

[Steven Lord]

If you have to operate on the numbers, datetime can handle most of the conversion. You just have to handle the hour data.

VeryBadlyStoredDates = [2021061701;2021010100;1913061423]; % should be illegal
hourData = mod(VeryBadlyStoredDates, 100)

hourData = 3×1

1 0 23

yyyyMMdd = (VeryBadlyStoredDates-hourData)./100

yyyyMMdd = 3×1

20210617 20210101 19130614

DT = datetime(yyyyMMdd, 'ConvertFrom', 'yyyymmdd') + hours(hourData)

DT = 3×1 datetime array
   17-Jun-2021 01:00:00
   01-Jan-2021 00:00:00
   14-Jun-1913 23:00:00

[Bruno Carvalho]

Converting it into a string worked!!

Thank you so much. And i totally agree, storing dates like this just gave me more work for nothing...

[Bruno Carvalho]

If you can, answer again in a seperate answer so i can accept your answer

[Stephen23]

@Bruno Carvalho: you can accept this answer, if one of the comments includes the solution.