How can I check if a table contains numbers only?

Good evening,

I am trying to develop a MATLAB application that adds values to a table by reading them from an excel file, but these values need to be all numbers and the x-values in the table cannot be repeated twice. Can someone please help me?

Thank you

Edit: I forgot to mention that the program works, reads the data from the sheet, writes them on the table with the readtable functiion but I cannot implement validtation.

[Mario Malic]

I would suggest trying to import data into a cell (or other type that will make it easier to write it to the table) variable and remove the values you don't need from there. Then write it to table.

[Walter Roberson]

Can the x values be repeated once? 1 2 3 3 4 5 5 6 6 7 8 for example?

Answer 1

[Peng Li]

I guess your question re the x-values isn't quite clear.

For the first part of your question, it is tricky to determine whether an input is a number or contains other stuffs as well. There isn't an elegent way I think. You could either try (1) to convert it to a double, if it gives you a valid double, that orignal input contains only number (or number related stuffs +-E etc), or (2) to examine whether all members of an input belong to 0123456789-+E or whatever elements you think might be used in a valid number expression (using ismember). Either way, try to import the orignal Excel sheet using '%q' option for each column to force the table to be a cell of char, and using cellfun to handle each element of the cell.

Below an example:

testTbl =

  4×2 table

       A          B   
    _______    _______

    {'123'}    {'123'}
    {'4E5'}    {'d'  }
    {'-56'}    {'67' }
    {'888'}    {'999'}

>> isNum = cellfun(@(x) all(ismember(x, '0123456789-+E')), testTbl.A);
if isNum
    testTbl.A = str2double(testTbl.A);
end
>> testTbl

testTbl =

  4×2 table

      A         B   
    _____    _______

      123    {'123'}
    4e+05    {'d'  }
      -56    {'67' }
      888    {'999'}

>> isNum = cellfun(@(x) all(ismember(x, '0123456789-+E')), testTbl.B);
if isNum
    testTbl.B = str2double(testTbl.B);
end
>> testTbl

testTbl =

  4×2 table

      A         B   
    _____    _______

      123    {'123'}
    4e+05    {'d'  }
      -56    {'67' }
      888    {'999'}

Answer 2

[Image Analyst]

Did you try the readmatrix() function? I believe it will import only numbers. Otherwise use xlsread() to get only the numbers.