How to save datetime values in an array?

Hi I am picking datetime value that is in this format

      05-Feb-2015 18:02:47   05-Feb-2015 18:02:51   05-Feb-2015 18:02:55

I want to save it in an array so that later I can plot it. I am getting error to convert from datetime to double. What should i do?

[venky]

are u importing datetime values from excel sheet?

[yashvin]

I already imported it..while processing,..i am actually picking specific datetime values and saving it in an array.

I just tried using datevec and saving all the numbers in an array...any suggestion?

[venky]

you are trying to store character into numeric arry(double) without any conversion...it doesnt have any meaning.if you want to store in double type first convert string { str_numeric = uint16(str) } into str_nemeric and store this str_numeric in double type array. please refer the below code for ur persual.

>> d1

d1 =

24-Jun-2015 13:50:32

>> d2=12345

d2 =

       12345

>> whos Name Size Bytes Class Attributes

d1        1x20               40  char                
d2        1x1                 8  double

[Guillaume]

datetime is not characters! It's its own type.

[yashvin]

Hi Guillaume,

Using your d1 for example,I had tried this this

    time_match1(i,:)=datevec(d1));

and later

    time_planned_way=datetime(time_match1)';

It is inside a for loop though. i will converting it in a string too! let me try

[Guillaume]

Clarification, the d1 example is nothing to do with me and the OP (Venky) appears to confuse the char type with the datetime time. He (she?) also does not seem to understand string to numeric conversion.

Answer 1

[Guillaume]

If you're getting this error it's because you're trying to put a datetime object in a preinitialised array (possibly with zeros ?) of double. I presume you preinitialise the array, because the datetime objects are created / obtained in a loop.

You can't put datetime objects in a preinitialised array of double (you can only put doubles in there). The datetimes have to go in a preinitialised array of datetime. One simple way of initialising such an array:

darr = datetime(zeros(10,1), 0, 0); %a 10x1 array of datetime

Note that there will be a simpler way of doing this in the next version of matlab.

[yashvin]

When i save the values using this kind of array, only i am getting my date...no time

[Guillaume]

This kind of array is just a preinitialised array of datetimes. A datetime array always holds a time even if it does not display it. (For example if you type darr.Hour you will get the hours you stored in there)

You can change the display of the datetime with the Format property of the array. This will display the time:

darr.Format = 'default';

[yashvin]

Thanks! I am using this approach!

[yashvin]

@ Guillaume

One more question: I am trying to save both a float or integer value together with a datetime value in an array. Anyway of making both these values cohabitate in an array?

   d= 5.5
  e = 05-Feb-2015 18:15:59
f= [d e]

Of course this is an error. But I am trying to map integers values to a datetime value. How i can do this. Should i change the datetime to a string?

[Guillaume]

A matrix can store data of only one type. So you can't put datetimes and float together, or float and integer together, or float and string together.

There are various kind of heterogeneous containers available in matlab, the simplest being cell arrays and tables

 f1 = {d e}; %cell array
 f2 = table(d, e, 'VariableNames', {'index', 'date'}); %table