How can I check if a table contains numbers only?

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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.
  2 Comments
Walter Roberson
Walter Roberson on 9 May 2020
Can the x values be repeated once? 1 2 3 3 4 5 5 6 6 7 8 for example?

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Accepted Answer

Peng Li
Peng Li on 9 May 2020
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'}

More Answers (1)

Image Analyst
Image Analyst on 9 May 2020
Did you try the readmatrix() function? I believe it will import only numbers. Otherwise use xlsread() to get only the numbers.

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