# Not able to convert string to seconds! Even though I am using datenum function. How can it be solved?

4 views (last 30 days)
John on 30 Jul 2023
Commented: Walter Roberson on 30 Jul 2023
I have been trying to convert time string from a large datal, but it Matlab gives me "Unrecognized millisecond format. Format string: HH:MM:SS.FFFF."
And I would like to get the data immediately from the file instead of importing them.
The format of the string is
12:10:02.908990
Here is the code:
t1;
datenum(t1,'HH:MM:SS.FFFF')

masoud sistaninejad on 30 Jul 2023
in MATLAB R202a and later you can use
datetime command like this ...
t1 = '12:10:02.908990'
t1 = '12:10:02.908990'
datetime(t1)
ans = datetime
30-Jul-2023 12:10:02

Walter Roberson on 30 Jul 2023
Edited: Walter Roberson on 30 Jul 2023
datenum() only supports up to millisecond resolution -- so at most FFF .
Also, your input format needs to account for the entire input string. You cannot just specify FFF and expect it to stop parsing after it reads 3 digits of milliseconds.
t1 = '12:10:02.908990';
d = duration(t1, 'InputFormat', 'hh:mm:ss.SSSSSS', 'format','hh:mm:ss.SSSSSS')
d = duration
12:10:02.908990
datenum_you_were_looking_for = seconds(d) / (24 * 60 * 60)
datenum_you_were_looking_for = 0.5070
ds = datestr(datenum_you_were_looking_for, 31) %cross-checking
ds = '0000-01-00 12:10:02'
I don't think the number of days since the beginning of "0 AD" is going to be useful, especially with the lost resolution (because datenum just do not have the resolution)- You should probably be seriously considering getting rid of using datenum()
##### 3 CommentsShow 1 older commentHide 1 older comment
Stephen23 on 30 Jul 2023
Edited: Stephen23 on 30 Jul 2023
"What are other alternatives to datenum()? "
Lets read the DATENUM documentation and see what it tells us:
The DURATION class would suit your input data (times given as hours, minutes, seconds + fraction of second). Note the DURATION class has properties and methods that you will find useful.
Walter Roberson on 30 Jul 2023
datetime and duration classes have the resolution needed, but their default Format does not include full resolution for display purposes.

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