how to read a text file as datetime input?

Hi everyone,

I have a text file with tiem date format YYYY-MM-DD HH:MM:SS. I want to load it and convert it to datenum. Here is what i attempt so far. (data attached)

 cd_ev=readmatrix('tt.txt'); % file attached

 %Or 
 t = load('tt.txt','InputFormat','yyyy-mm-dd HH:mm:ss')
 
 %or
 
 rr=readtable('tt.txt', 'Format','yyyy_mm_dd/dd hh:mm:ss');
 

None of the above serve fro my purpsoe.

Answer 1

[Walter Roberson]

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1156138/tt.txt';
t1 = readtable(filename, 'ReadVariableNames', false);
t1.Properties.VariableNames{1} = 'Date';
t1.Date.Format = 'yyyy_MM_dd/dd HH:mm:ss';  %MM for month, HH for 24 hour hour

%verify
t1.Date(1:5)

ans = 5×1 datetime array
   2015_07_10/10 04:43:53
   2015_07_18/18 02:57:26
   2015_07_27/27 04:59:29
   2015_07_27/27 22:15:44
   2015_09_13/13 08:23:58

I am having trouble thinking of a good reason to repeat the day like you asked to.

[Andi]

@Walter Roberson

oh, it just a typo, no need to repeat the day. :P

But, the key thing is when i convert this to data num for further processing, there is still an error.

clear all
clc

filename = 'tt.txt';
t1 = readtable(filename, 'ReadVariableNames', false);
t1.Properties.VariableNames{1} = 'Date';
t1.Date.Format = 'yyyy_MM_dd HH:mm:ss';  %MM for month, HH for 24 hour hour
aa=t1.Date;
cand_ev=datenum(aa);


for jj=1:10
     b=cand_ev(:,jj);
     aa(jj)= addtodate(b, 3, 'day');
     bb(jj)= addtodate(b, -3, 'day');
end 
CE_U=aa;
CE_L=bb;

Error:

Error using addtodate

Date number must be a real numeric scalar.

[Walter Roberson]

Why do you need datenum? You can

aa = t1.Date + days(3);
bb = t1.Date - days(3);

[Andi]

yes, i want to add and subtract 3 days from this time value. But it shoudl be in datenum because other datasets i am using in my code are in datenum

[Walter Roberson]

Consider converting the dates in the other databases to datetime(), using datetime() with 'convertfrom', 'datenum'

[Walter Roberson]

aa = datenum(t1.Date + days(3));
bb = datenum(t1.Date - days(3));

[Andi]

yes, i did but i dont known why datenum values are not competable with other datasets.

[Walter Roberson]

addtodate is specifically designed to only accept scalar datenum. b=cand_ev(:,jj); selected a vector of datenum entries, so addtodate(b) failed.