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

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John
John 2023-7-30
评论： Walter Roberson 2023-7-30
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')

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回答（2 个）

masoud sistaninejad
Ran in:
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
Walter Roberson 2023-7-30
编辑：Walter Roberson 2023-7-30
Ran in:
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()
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Stephen23
Stephen23 2023-7-30
编辑：Stephen23 2023-7-30
"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
Walter Roberson 2023-7-30
datetime and duration classes have the resolution needed, but their default Format does not include full resolution for display purposes.

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