How to convert time in nanosecond to numeric value in order to be able to compare these timeseries?

Hello,

I have the number of *.csv files that are same structure (same column number), but row numbers are different. I use readtable to upload data to matlab. I need to compare timeseries of different csv files. The example of timeseries:

'08:34:37.762296992'

'08:34:37.762450580'

'08:34:37.762450580'

'08:34:37.762460422'

'08:34:37.762460422'

'08:34:37.762472108'

'08:34:37.762472108'

'08:34:37.762543205'

'08:34:37.762543205'

'08:34:37.762673812'

How to convert this type to timeseries to numeric value in order to be able to compare them?

Answer 1

[madhan ravi]

T=readtable('mycsv.csv')
datetime(T{:,1},'InputFormat','HH:mm:ss.SSS') %highly recommended

[Mantas Vaitonis]

But as I mentioned csv file consist of number of columns, an example:

'14:00:26.525135545'	898	23252	'ESM8'
'14:00:26.527732834'	899	7594	'ESM8-ESH9'

Thus how to define datetime format only for one column?

[madhan ravi]

see edited answer

[Mantas Vaitonis]

Datenum and datevec does work but they are not sensitive enough becasue datenum gives same result for boths of these values (12:04:18.732122198 and 12:04:18.732140388), however this line

datetime(T{:,1},'InputFormat',HH:mm:ss.SSSSSSSSS')

Gives the result '15-Nov-2018 08:34:37', and decimal numbers are not taken in to account. Is there a way using nanoseconds?

[madhan ravi]

sorry my typo it's

datetime(T{:,1},'InputFormat','HH:mm:ss.SSS') 

make sure to accept the answer if it worked

[Mantas Vaitonis]

Thank you, I did fine later that mistake however datenum and datevec they are not sensitive enough becasue datenum and datevec gives same result for boths of these values (12:04:18.732122198 and 12:04:18.732140388), however this line

datetime(T{:,1},'InputFormat',HH:mm:ss.SSSSSSSSS')

Gives the result '15-Nov-2018 08:34:37', and decimal numbers are not taken in to account. Is there a way using nanoseconds?

[Mantas Vaitonis]

Did change InputFormat to Format and it did work

datetime(T{:,1},'Format','HH:mm:ss.SSSSSSSSS') 

[madhan ravi]

Perfect @Mantas

[Steven Lord]

If you want to ensure MATLAB displays the numbers using the same Format that was used to import them, you can specify both 'InputFormat' and 'Format' in your datetime call.

fmt = 'HH:mm:ss.SSSSSSSSS';
datetime(T{:,1},'InputFormat', fmt, 'Format', fmt)

Even if you operate on a datetime that doesn't display the fractional seconds, as long as the datetime was created / computed using fractional seconds they're still present and will be taken into account by the relational operators. In the example below neither T nor T2 show seconds, but T2 is a quarter second after T.

T = datetime('today', 'Format', 'dd MMM yyyy')
T2 = T + seconds(0.25)
T2 > T % returns true

[madhan ravi]

Thank you @Steven Lord really useful

[Peter Perkins]

Also: these two

datenum(T{:,1})
datevec(T{:,1})

aren't really gonna work correctly, because datenums and datevecs just don't support timestamps to ns resolution.

[madhan ravi]

Thank you for the information @Perkins