How do I convert a string to a date?

Currently I have the string:

2017-03-18 03:26:42.000000

I want to convert this to a date, and I use the following function:

datetime(my_string,'InputFormat','yyyy-mm-dd HH:MM:SS')

However, when I do this I get the following error:

Unable to parse '2017-03-18 03:26:42.000000' as a date/time using the format 'yyyy-mm-dd HH:MM:SS'.

I have also tried

datetime(my_string,'InputFormat','yyyy-mm-dd HH:MM:SSSSSSSSS')

and

datetime(my_string,'InputFormat','yyyy-mm-dd HH:MM:SS.SSSSSSS')

But none of these seem to work. How would I go about doing this?

Answer 1

[Guillaume]

Carefully read the documentation of the Format property. The month identifier is uppercase M and the minute identifier is lowercase m. The seconds field is lowercase s with the fractional part as uppercase S. So:

datetime(my_string,'InputFormat','yyyy-MM-dd HH:mm:ss.S')

if you want to display the fractional seconds by default:

datetime(my_string,'InputFormat','yyyy-MM-dd HH:mm:ss.S', 'Format', 'yyyy-MM-dd HH:mm:ss.SSS')

[Douglas Leaffer]

The date and time vectors are the same length. I think perhaps the problem lies with the way the .txt file is imported. I have attached an excerpt of the file if you have bandwidth to suggest further help. The coumns of interest are date = column 7; time = column 8

[Michael Connolly]

Thank you for posting this! It fixed my problem.

Answer 2

[Rik]

It is a bit confusing, but the capital S only denotes the fraction of a second, so not the second itself. The code below works.

my_string='2017-03-18 03:26:42.000000';
datetime(my_string,'InputFormat','yyyy-MM-dd HH:mm:ss.SSSSSS')

[Guillaume]

Note that for decoding you only need one S regardless of the number of fractional digits. The number of S only affects the datetime display when it is part of the Format property

[Rik]

Good to know, thanks Guillaume.

[Amini]

thanks for your answers, I have to use the function datetime, actually I want to find the differences between timestamps. (for example: row 2 minuse row 1). the problem is two characters before the DAY 24 '[ and also the format of MONTH Sep. how should I use this function to approach this problem? thanks in advance. @Rik @Guillaume @Douglas Leaffer

[Amini]

in this way it works:

DateStrings = {'24/09/2021:10:56:23'};
t = datetime(DateStrings,'InputFormat','dd/MM/yyyy:HH:mm:ss')

But my date is 24/Sep/2021:10:56:23

and in this way it doesn't work

DateStrings = {'24/Sep/2021:10:56:23'};
t = datetime(DateStrings,'InputFormat','dd/MM/yyyy:HH:mm:ss')

%again, beside the problem of two extra characters

[Amini]

I found it how to eliminate the extra characters, using erase but still stacked with MONTH part