Plot datetime data from a cell array?

I have data set shown in fig. But I do not how to access to the data.

I try to use: plot(index{2:end, 1}, cell2mat(index(2:end, 2)), 'b'), but it does not work.

Answer 1

[Stephen23]

A cell array containing lots of scalar arrays indicates that your data is arranged sub-optimally. You would be much better off using a table, or perhaps two separate homogenous vectors (i.e. a datetime array and a numeric array).

Converting to two homogenous arrays is probably the easiest way to plot the existing (badly designed) data:

dt = [index{2:end,1}];
ix = [index{2:end,2}];
plot(dt,ix)

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

[Yufei Cao]

Hi, Stephen, Thanks for your reply and links. It helps me a lot.

[Yufei Cao]

Hi, Stephen,

The orginal data is an .xlsx file. I loaded the data into matlab by using

index = readcell('index.xlsx', 'Sheet', 1);

which gives the table shown in the figure.

You mentioned the data is not well arranged. So I think you mean that I should convert index into a table?

[Stephen23]

@Yufei Cao: try using readtable, and then access the relevant "variables" by name:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html

T = readtable(..);
plot(T.date,T.index)

[Yufei Cao]

Hi, Stephen,

Thank you so much for the comment! The information is very useful!