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

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Rajkumar 2023-3-18

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https://ww2.mathworks.cn/matlabcentral/answers/1930965-unable-to-concatenate-the-table-variables-var1-and-var2-because-their-types-are-cell-and-doubl

评论： Walter Roberson 2023-8-25

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

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Answer 1

Walter Roberson 2023-3-18

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

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Walter Roberson 2023-8-25

在 MATLAB Online 中打开

@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 2023-8-25

在 MATLAB Online 中打开

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