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

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')

Answer 1

[masoud sistaninejad]

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

Answer 2

[Walter Roberson]

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()

[John]

What are other alternatives to datenum()?

I have tried to use multiple functions to convert strings like '12:10:02.908990' to seconds, but I do not get them correctly.

I have a large amount of data, i.e., 300k samples, and I want to get the time in seconds that is associated with each sample to be able to analyze the data.

When I tried to import the data and then convert them in the import data to (HH:MM:SS), most of the time was lost due to the poor resolution.

If anyone has come across such an issue, please let us know how to figure it out.

[Stephen23]

"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]

datetime and duration classes have the resolution needed, but their default Format does not include full resolution for display purposes.