'Unable to concatenate the table variables 'Var1' and 'Var2', because their types are cell and double.' why this error is showing?

clear all; 
clc;
%read X sample
ix1 = readtable("x_sample_01.dat",'ReadVariableNames',false);
x1	=	table2array(ix1);

Answer 1

[Walter Roberson]

Your file contains a mix of text and numeric. What result are you expecting when you ask to convert it to a single array?

[Kazem Gheysari]

The problem is not from table2array.

If you just read the table, the beginning texts are deleted and just numbers are remained.

[Walter Roberson]

@Kazem Gheysari

I would suggest that your analysis is incorrect for this situation.

Var1 = {'hello';'bye'};
Var2 = [11; 22];
T = table(Var1, Var2)

T = 2×2 table
      Var1       Var2
    _________    ____

    {'hello'}     11 
    {'bye'  }     22 

writetable(T, 'temp_table.xlsx');

ix1 = readtable('temp_table.xlsx')

ix1 = 2×2 table
      Var1       Var2
    _________    ____

    {'hello'}     11 
    {'bye'  }     22 

x1 = table2array(ix1)

Error using {}
Unable to concatenate the table variables 'Var1' and 'Var2', because their types are cell and double.

Error in table2array (line 37)
a = t{:,:};

[Kazem Gheysari]

@Walter Roberson , when you do not know my analysis, why dod you say it is incorrect?

If you like to improve MATLAB, accept the reported problem that the users tell.

I have same issue but MATLAB give this error when I use

readtable

I created another excel file with more than 1000 row and MATLAB works fine.

The problem return to the situation that MATLAB automatically determine the datatype of column.

[Walter Roberson]

@Kazem Gheysari

I can say that your analysis is incorrect for the situation because I demonstrated a case where table2array() causes exactly the error that the error reports.

Furthermore, in cases where "just numbers are remained" then table2array() will not have any problems. Here is an example in which readtable is removing leading text, leaving only numbers, and you can see that what is left does not cause any problem with table2array()

headerlines = {'heading out to Eden'; 'No more trouble in my body or my mind'};
Var1 = [101; 201];
Var2 = [11; 22];
top = [headerlines, cell(2,1)];
bottom = [num2cell(Var1), num2cell(Var2)];
C = [top; bottom]

C = 4×2 cell array
    {'heading out to Eden'                  }    {0×0 double}
    {'No more trouble in my body or my mind'}    {0×0 double}
    {[                                  101]}    {[      11]}
    {[                                  201]}    {[      22]}

writecell(C, 'temp_table.xlsx');

ix1 = readtable('temp_table.xlsx')

ix1 = 2×2 table
    Var1    Var2
    ____    ____

    101      11 
    201      22 

x1 = table2array(ix1)

x1 = 2×2

101 11 201 22

writecell(C, 'temp_table.csv');
dbtype temp_table.csv

1     heading out to Eden,
2     No more trouble in my body or my mind,
3     101,11
4     201,22

[Walter Roberson]

The case where there are empty columns get converted to doubles and filled with NaN -- no problem with table2array()

headerlines = {'Var1', 'Var2'};
Var1 = cell(2,1);
Var2 = [11; 22];
top = headerlines;
bottom = [Var1, num2cell(Var2)];
C = [top; bottom]

C = 3×2 cell array
    {'Var1'    }    {'Var2'}
    {0×0 double}    {[  11]}
    {0×0 double}    {[  22]}

writecell(C, 'temp_table.xlsx');

ix1 = readtable('temp_table.xlsx')

ix1 = 2×2 table
    Var1    Var2
    ____    ____

    NaN      11 
    NaN      22 

x1 = table2array(ix1)

x1 = 2×2

NaN 11 NaN 22

writecell(C, 'temp_table.csv');
dbtype temp_table.csv

1     Var1,Var2
2     ,11
3     ,22