Cell contents reference from a non-cell array object table2array

% import data and convert into an array
a = open('dst1993.mat');
x = table2array(a.Dst_val);
b = open('ae1993.mat');
x2 = table2array(b.AE_val);

gets me error:

Cell contents reference from a non-cell array object.

Error in table2array (line 27)
a = t{:,:};

Error in dstvsae (line 11)
x = table2array(a.Dst_val);

I'm really bad at coding but I need to get this done :/

[Paolo]

I suspect a.Dst_val is not a table. Can you add your .mat file to the question?

[Hannah Joyce]

here it is

[Paolo]

Right, a.Dst_val is already an array of doubles. What do you want to do with your data?

[Hannah Joyce]

I need to plot the two things against each other, but the first column is supposed to be a date but doesn't really look like one

[Paolo]

Those are serial date numbers. Read more about it here.

What is the desired output for your dates? Try:

 a = load('dst1993.mat');
 dates = datetime(a.Dst_val(1:720),'ConvertFrom','datenum')';
 values = a.Dst_val(721:end)';
 T = table(dates,values)

T is a now a Table containing variables dates and values. Then simply plot your data:

 plot(T.dates,T.values);

[Hannah Joyce]

so if I wanted to plot this data set on the same time axis (time is column one, columns 2, 3 and 4 are different data sets) I'd just copy that and edit it to be ae1993.mat and AE_val instead of Dst?

or would it be a bit more complicated as there are 3 columns of different data?

Answer 1

[Jan]

Start with:

Data = load('dst1993.mat')

What do you get for:

class(Data.Dst_val)

? If you know this, the conversion to an array should be easy.

[Hannah Joyce]

Undefined variable "Data" or class "Data.Dst_val".

Error in dstvsae (line 10)
class(Data.Dst_val)

Answer 2

[Peter Perkins]

In a recent-ish version of MATLAB, try this:

>> load('ae1993.mat')
>> t = array2table(AE_val,'VariableNames',{'Time' 'X' 'Y' 'Z' 'W'});
>> t.Time = datetime(t.Time,'ConvertFrom','datenum');
>> tt = table2timetable(t);
>> head(tt)
ans =
  8×4 timetable
            Time            X     Y      Z     W 
    ____________________    __    __    ___    __
    01-Sep-1993 00:00:00    35    28     -6    10
    01-Sep-1993 01:00:00    36    26     -9     8
    01-Sep-1993 02:00:00    80    49    -30     8
    01-Sep-1993 03:00:00    50    40     -9    15
    01-Sep-1993 04:00:00    47    37     -9    13
    01-Sep-1993 05:00:00    36    23    -13     4
    01-Sep-1993 06:00:00    44    27    -16     4
    01-Sep-1993 07:00:00    48    32    -16     7
>> plot(tt.Time,tt.Variables)

That's kind of pretty.

[Hannah Joyce]

thank you :)

its the auroral electrojet data in the ionosphere from september 1993