DateTime stamps in uitable from thingSpeakRead() data

I cannot figure out how to add the date/time stamp data in chnX to the uitable without generating an error.

chnId = #######;
apiReadKey = 'thingspeak-api-read-key';
[data, chnX] = thingSpeakRead(chnId, 'Fields',[1, 2, 3, 4, 5, 6], ...
                                   'NumPoints', 5, ...
                                   'ReadKey', apiReadKey);
% Visualize data with a uitable
f = figure();
uit = uitable(f);
uit.Data = data;
uit.ColumnName = {'A0','A1','A2','A3','A4','A5'};
uit.Position = [5 5 450 150]; %[left bottom width height]
uit.ColumnWidth = {65,65,65,65,65,65};

Answer 1

[Cris LaPierre]

My apologies for not catching onto that initially. While uifigure is needed to add datetimes, it is not supported in ThingSpeak. You can find a list of the table properties and their accepted inputs here. From that link, you can see that only numeric, logical, or cell arrays can be passed to the Data property of uitables created with the figure function.

Option 1

You could just display the table without trying to put it into a uitable.

chnId = 1044636;
apiReadKey = 'SJS9JQYUSJSJZYW3';
data = thingSpeakRead(chnId, 'Fields',[1, 2, 3, 4, 5, 6], ...
                                   'NumPoints', 5, ...
                                   'ReadKey', apiReadKey);
% Visualize data
varNames = {'A0','A1','A2','A3','A4','A5'};
Tbl = array2timetable(data,'RowTimes',chnX,'VariableNames',varNames)

Option 2

If you really want it in a table, and

1. don't want to compress the date to a single numeric representation (datenum), and
2. also don't want to split the date into parts (datevec), creating a column for each one (Y,M,D,h,m,s)

the answer is to create a cell array. To do this, you need to turn the dates into a character array (datestr), and then turn the combined data into a cell array. The easiest way I could find to do that was with table2cell, which meant I first had to turn the data into a table (array2table).

I noticed there is a maximum width allowed for a uitable, so I had to adjust the formatting of the timestamp to get all the columns to fit.

Here is what I came up with.

%% Read Data %%
[data, chnX] = thingSpeakRead(1044636, ...
    'Field', [1, 2, 3, 4, 5, 6], ...
    'NumPoints', 5);

%% Convert chnX + data to a cell array %%
Tbl = array2table(data);
Tbl.timestamp = datestr(chnX,'mm/dd/yy HH:MM');
Tbl = movevars(Tbl,"timestamp","Before",1);
tblData = table2cell(Tbl);

%% Visualize Data with a uitable %%
f = figure;
uit = uitable(f);
% uit.Data = [dates(:,1),dates(:,2:3)*[1;.01],dates(:,4:6)*[60;1;1/60],data];
uit.Data = tblData;
uit.ColumnName = {'Timestamp','A0','A1','A2','A3','A4','A5'};
uit.Position = [5 5 590 150]; %[left bottom width height]
uit.ColumnWidth = {130,65,65,65,65,65,65};

[Mark Kiehl]

The 2nd option worked out the best. Thank you so much for your help.

[Cris LaPierre]

It seems char is better than datestr. In that case, replace that line of code with the following.

chnX.Format = 'MM/dd/yy hh:mm';
Tbl.timestamp = char(chnX);

Answer 2

[Cris LaPierre]

Try using uifigure instead of figure. We don't have access to your channel, so here's a quick mockup I did using a public channel. To support multiple data types in the output, I also had to add the "OutputFormat","table" Name-Value pair to thingSpeakRead.

chnId = 841669;

[data, chnX] = thingSpeakRead(chnId,'Fields',[1, 2],...
    'NumPoints', 5, ...
    "OutputFormat","table");

% Visualize data with a uitable
f = uifigure();
uit = uitable(f);
uit.Data = data;
uit.ColumnName = {'Date','A1','A2'};
uit.Position = [5 5 450 150]; %[left bottom width height]
uit.ColumnWidth = {150,65,65};

[Cris LaPierre]

Moved reply from Mark Keihl so it is a comment instead of an Answer

Cris,

Channel ID: 1044636 is public.

https://thingspeak.com/apps/matlab_visualizations/348076/edit

chnId = 1044636;
apiReadKey = 'SJS9JQYUSJSJZYW3';
[data, chnX] = thingSpeakRead(chnId, 'Fields',[1, 2, 3, 4, 5, 6], ...
                                   'NumPoints', 5, ...
                                   'ReadKey', apiReadKey);
% Visualize data with a uitable
f = figure();
uit = uitable(f);
uit.Data = data;
uit.ColumnName = {'A0','A1','A2','A3','A4','A5'};
uit.Position = [5 5 450 150]; %[left bottom width height]
uit.ColumnWidth = {65,65,65,65,65,65};

Your code never includes the datetime stamps from chnX (data doesn't include the datetime stamps from chnX). Changing "[data, chnX] = " to "data = " resolves that.

Your changes generate this error:

Unable to run the 'Table of Particle device digital inputs' function, because it is not supported for this product offering.

Caused by:

Error using matlab.internal.lang.capability.Capability.require (line 81)

This functionality is not available on remote platforms.

[Cris LaPierre]

The channel I used contains a timestamp in the data field, which then gets displayed in the uitable.

Could you provide the code that is producing the error?

[Mark Kiehl]

chnId = 1044636;
apiReadKey = 'SJS9JQYUSJSJZYW3';
data = thingSpeakRead(chnId, 'Fields',[1, 2, 3, 4, 5, 6], ...
                                   'NumPoints', 5, ...
                                   'ReadKey', apiReadKey);
% Visualize data with a uitable
f = uifigure();
uit = uitable(f);
uit.Data = data;
uit.ColumnName = {'A0','A1','A2','A3','A4','A5'};
uit.Position = [5 5 450 150]; %[left bottom width height]
uit.ColumnWidth = {65,65,65,65,65,65};

[Cris LaPierre]

I'm not getting an error. What version of MATLAB are you using?

Answer 3

[Mark Kiehl]

This is a online Visualization within ThingSpeak. https://thingspeak.com/apps/matlab_visualizations

If I read the data with the thingSpeakRead() function and then create a line plot, the datetime values in chnX are correctly understood by the plot() function, and some automatic formatting is performed. Based on this, the ISO8601 formatted (similar to JSON date/time format) seems to be understoon well by MatLab within that context.

What I want is a table that has the chnX datetime values in the first column of the table, and the numeric data in the remaining columns. If i execute .uit.Data = data; then I get the numeric values without an error. But when I attempt to display the chnX datetime values in a uitable, I experience the error. For example, the code below results in the error:

Error setting property 'Data' of class 'Table':

Data must be a numeric, logical, string, cell, or table array

Error in Table of Particle device ai channel data (line 9)

uit.Data = chnX;

[data, chnX] = thingSpeakRead(chnId, 'Fields',[1, 2, 3, 4, 5, 6], ...
                                   'NumPoints', 5, ...
                                   'ReadKey', apiReadKey);
f = figure();
uit = uitable(f);
uit.Data = chnX;