convert array string data in array serial number

this example clarify my problem

>> size(B)

ans =

463628 1

>> B(1)

ans =

"01/01/2008"

>> datenum(B(1,:),'dd/mm/yyyy')

ans =

733408

>> datenum(B,'dd/mm/yyyy')

Error using datenum

DATENUM failed.

Caused by:

Error using dtstr2dtnummx

Failed to convert from text to date number.

i can convert the single string but not the array of strings

[Stephen23]

@Luca Re: please save your data in a MAT file and upload it by clicking the paperclip button.

[Luca Re]

dataan.m

[Stephen23]

@Luca Re: lots of the DATAAN string elements are empty, i.e. have no characters:

Clearly empty text does not match the specified date format and will fail when you try to parse it with DATENUM.

[Luca Re]

thank..

they are empty because I have preallocated the variable and not all array vectors have the same number of elements

B=strings(righe,colum);

What do you recommend if I have empty array elements? fill them with false dates for the command to work correctly

[Stephen23]

"What do you recommend if I have empty array elements?"

Use DATETIME instead of deprecated DATENUM:

B = ["01/01/2008";""]

B = 2×1 string array
    "01/01/2008"
    ""

D = datetime(B, "InputFormat","dd/MM/yyyy")

D = 2×1 datetime array
   01-Jan-2008
   NaT        

[Luca Re]

yes but i want do preallocate it

is it correct to do it like this? (i need 5600 element in this matrix and I have to assign values ​​read from .txt

dataan=NaT(righe,colum);

Answer 1

[Steven Lord]

Unless you're using an older release where it is not available I strongly recommend you use datetime instead of serial date numbers. Note I've changed your B slightly to make it clear that datetime is importing it correctly, not confusing the day and month information.

B = "02/03/2008";
dt = datetime(B, "InputFormat", "dd/MM/yyyy")

dt = datetime
   02-Mar-2008

With a datetime array a lot of operations are easier and easier to interpret than with a list of date numbers. As an example, what's the day after dt?

nextDay = dt + days(1)

nextDay = datetime
   03-Mar-2008

[Luca Re]

v =

"01/01/2008"

>> datetime(v,'dd/mm/yyyy' )

Error using datetime

Wrong number of arguments.

i've problem to use it

[Stephen23]

"i've problem to use it"

It will work when you read and follow the DATETIME documentation or the example that Steve Lord showed you. Why did you change the syntax to something completely different?

S = "01/01/2008";
D = datetime(S, 'InputFormat','dd/MM/yyyy')

D = datetime
   01-Jan-2008

[Luca Re]

thanks..I mess around a bit with these formats