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String date and time identification

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Hello, I have the following string:
date= '2021-07-011407404.5'
From here I would like to detect date and time in the following formar: 2021-07-01 14:07:40, the last number (e.g. 4.5) is another data and this number it can vary like 16.50, and so on.
Thank you for your support

Accepted Answer

Walter Roberson
Walter Roberson on 5 Jan 2023
datetime() has no ability to have a format item along the lines of "arbitrary number to be ignored". You cannot specify anything along the lines of 'yyyy-MM-ddHHmmss%*f' with the intent being that after the ss field that an arbitrary floating point number is to be expected but discarded. It does not even have the ability to specify that a particular fixed numeric digit is to be expected but ignored
datetime('2021-07QA', 'InputFormat', "uuuu-MM'QA'") %works
ans = datetime
datetime('2021-075A', 'InputFormat', "uuuu-MM'5A'") %nope
Error using datetime
Unable to convert '2021-075A' to datetime using the format 'uuuu-MM'5A''.
Because of this, you need to remove those extra digits from the input before you call datetime(), such as using indexing as shown by @Star Strider and @Cameron

More Answers (3)

Star Strider
Star Strider on 5 Jan 2023
Edited: Star Strider on 5 Jan 2023
If they all have the same format —
date= '2021-07-011407404.5'
date = '2021-07-011407404.5'
DT = datetime(date(1:16), 'InputFormat','yyyy-MM-ddHHmmss', 'Format','yyyy-MM-dd HH:mm:ss')
DT = datetime
2021-07-01 14:07:40
LastNumber = str2double(date(17:end))
LastNumber = 4.5000
They must all have the same formats for this to work.
EDIT — (5 Jan 2023 at 18:28)
Added 'Format' name-value pair to datetime call.
  1 Comment
Stephen23 on 5 Jan 2023
An alternative to indexing would be to use EXTRACTBEFORE(), which also works on string/cell of char arrays.

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Cameron on 5 Jan 2023
Edited: Cameron on 5 Jan 2023
How consistent are is the information in your variable called date? Will they always look like what you have described in your question? You should consider renaming the variable from date to something that is not already a MATLAB function like DateValue.
DateValue = '2021-07-011407404.5';
NewDate = DateValue(1:10);
NewTime = [DateValue(11:12),':',DateValue(13:14),':',DateValue(15:16)];
RemainingInfo = str2double(DateValue(17:end));
%from here you can make them into formats MATLAB recognizes as datetime
DateTimeValue = datetime([NewDate,' ',NewTime]);

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 5 Jan 2023
Here is one of the possible ways of displaying the time strings:
DD= '2021-07-011407404.5';
DDate = DD(1:10)
DDate = '2021-07-01'
D2 = DD(11:16);
DTime = strcat([D2(1:2) ':' D2(3:4) ':' D2(5:6)])
DTime = '14:07:40'
D3 = DD(17:end);
DTime2 = strcat([D3(1) '.' D3(end)])
DTime2 = '4.5'
ALL = ['Date: ' DDate ' Time: ' DTime ' Seconds: ' DTime2]
ALL = 'Date: 2021-07-01 Time: 14:07:40 Seconds: 4.5'


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