How to convert time column into a regular array?

I have a table with first column as time series, and other columns as other parameters that changes with time. I want to convert the time series into an array for plaotting. I tried following code:

A_time = A(:,1);

A_time_array = table2array(A_time);

This method works for all the numeric columns. However, it errors out in the time column. Can someone suggest a better way?

[Stephen23]

"Can someone suggest a better way?"

Convert the "time series" to datetime objects and plot using them.

Answer 1

[Star Strider]

If the time series are a datetime array, they can easily be plotted as funcitons of that variable. It would be best to convert them to a datetime array if they are not already.

The other (less-desirable) option is to convert them to a datenum array and then use the datetick function.

.

[Star Strider]

Anjali Mishra’s Answer became this Comment —

Thank you Star Stider. Here is the scenario. A is a table with first column as time and other columns as other parameters. A am

>> A(:,1)

A(:,1)=

4×1 cell array

{[2021-11-14 19:16:02.328]}

{[2021-11-14 19:16:02.430]}

{[2021-11-14 19:16:02.533]}

{[2021-11-14 19:16:02.640]}

>> temperature = table2array(A(:,2));

This is expected to be x-axis on the plot with temperature

>> plot(A(:,1), temperature, 'r*')

results into A_time being invalid arguments.

Is there a way to keep this format of time as in 2021-11-14 19:16:02.328?

[Star Strider]

Those dates and times must be present in the file as character or string arrays. It is not possible to work with them as they are presented, so having the original file would help.

Assuming that they are (or can be made to be) read as character arrays or string arrays, the conversion is straightforward —

A = {{['2021-11-14 19:16:02.328']}
    {['2021-11-14 19:16:02.430']}
    {['2021-11-14 19:16:02.533']}
    {['2021-11-14 19:16:02.640']}}

A = 4×1 cell array
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}

Aa = datetime([A{:}], 'InputFormat','yyyy-MM-dd HH:mm:ss.SSS',  'Format','yyyy-MM-dd HH:mm:ss.SSS').'

Aa = 4×1 datetime array
   2021-11-14 19:16:02.328
   2021-11-14 19:16:02.430
   2021-11-14 19:16:02.533
   2021-11-14 19:16:02.640

Using the same format descriptor string for both 'InputFormat' and 'Format' causes the output to match the input.

.

Answer 2

[Jon]

t = seconds(A_time.Time - A_time.Time(1))

[Anjali Mishra]

This also works equally well.