My variable names for a table aren't the same length even though they are both 20 long and won't change

How can I reset the variable names and change them to new ones? The variable names are "Var1_1, Var1_2..." are they only one variable? There are 20 columns. I'm using the App Designer and exporting them the excel using writetable.

global LineNumber
Names={'CH1','CH2','CH3','CH4','CH5','CH6','CH7','CH8','CH9','CH10','CH11','CH12','CH13','CH14','CH15','CH16','CH17','CH18','CH19','CH20'};
InputFile=('Temperature Table Line %s.xlsx');
filename=sprintf(InputFile,LineNumber);
t=table(app.UITable3.Data);
t.Properties.VariableNames=Names;   % My error is here
writetable(t,filename,'WriteVariableNames',true)

%% The VariableNames property must contain one name for each variable in the table.
error ^

There are 20 CHs and 20 columns in UITable3, why isn't there one name for each variable?

Answer 1

[Voss]

I don't know what class app.UITable3.Data is, but in another question (here), you say that calling writematrix(app.UITable.Data) works but only includes the values.

That indicates that app.UITable.Data is a matrix, and if so, you can convert it to a cell array and use that cell array as a comma-separated list of arguments for the table function, in order to build a table with 20 variables:

% Names = {'CH1','CH2','CH3','CH4','CH5','CH6','CH7','CH8','CH9','CH10','CH11','CH12','CH13','CH14','CH15','CH16','CH17','CH18','CH19','CH20'};
Names = sprintfc('CH%d',1:20) % easier

Names = 1×20 cell array
    {'CH1'}    {'CH2'}    {'CH3'}    {'CH4'}    {'CH5'}    {'CH6'}    {'CH7'}    {'CH8'}    {'CH9'}    {'CH10'}    {'CH11'}    {'CH12'}    {'CH13'}    {'CH14'}    {'CH15'}    {'CH16'}    {'CH17'}    {'CH18'}    {'CH19'}    {'CH20'}

% I'm using a made up matrix, since I don't have app.UITable3
data = rand(5,20);

% You would do this instead:
% data = app.UITable3.Data;

% Then convert the matrix data to an appropriate cell array:
cell_data = num2cell(data,1)

cell_data = 1×20 cell array
    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}    {5×1 double}

% and use that as arguments in table, to get a table with multiple
% variables (rather than a table with a single variable, each row 

t = 5×20 table
      CH1        CH2        CH3        CH4        CH5         CH6        CH7         CH8        CH9        CH10        CH11       CH12        CH13       CH14        CH15       CH16       CH17       CH18        CH19        CH20  
    _______    _______    _______    _______    ________    _______    ________    _______    _______    ________    ________    _______    ________    _______    ________    _______    _______    _______    ________    ________

    0.83495    0.57324    0.15406    0.71764     0.15624    0.48722     0.41819    0.70706    0.47438     0.04234      0.6775    0.77621    0.093156    0.77831     0.22619    0.49245    0.95948    0.63162    0.034427    0.070848
    0.35707    0.35558    0.94107    0.42838    0.018153    0.95162     0.99955    0.11608    0.29396     0.66961     0.80899    0.50561     0.77366    0.55691    0.080486     0.8886    0.40172    0.16117     0.83815     0.55945
    0.84943    0.34997    0.17635    0.71218     0.62415    0.76967     0.58989     0.6685    0.66363     0.25907      0.7817    0.43712      0.1938    0.81385     0.10315    0.43355     0.6711    0.68076     0.11415     0.24839
     0.2884    0.76242    0.51344    0.73116     0.18381    0.89611    0.087377    0.37085    0.32857      0.2294    0.050061    0.99957     0.38818    0.54801        0.41     0.4613    0.64436    0.68862     0.81377     0.26697
    0.77982    0.29926    0.12153    0.87523     0.95481    0.16382     0.77678    0.99808    0.73635    0.068061     0.76021    0.60053     0.02392    0.57137      0.8207    0.69833    0.69633    0.70762     0.30656     0.89504

% of which has multiple elements):
t = table(cell_data{:},'VariableNames',Names) % and you can include the variable names here

Then use writetable with the table t as you already have it (or without 'WriteVariableNames',true, since that is the default):

writetable(t,filename)