How to check if an entire column of string variables can potentially be converted to numerical values?

I have a column variable normally look like this:

'ABC1234'
'DEC1236'
'CFG5645'
... 

Once in a while the column data will be like this, i.e., composed entiredly of strings that can be converted to numerical values.

'1234567'
'2312456'
'7863522'
...

When this happens, I want to use str2num to convert them into numerical values first before using writetable to put them into an Excel file. Otherwise, I would see all those yellow diamonds with ! inside next to each row of the column to indicate errors.

So how do I detect if all elements in an entire column can potentially be converted to numerical values?

Also when I treid to use str2num, why am I getting the below error?

Input must be a character vector or string scalar.

[Wiley Mosley]

Typically I use str2double() instead of str2num. Try using that, and if it cannot convert it will return a NaN. You can then do a sweep removing the NaN with [ ] . The strings that can be converted will, and the ones that can't can be removed.

[Leon]

Cool. It works! I did not know there is a str2double() before.

Thank you so much.

[Guillaume]

As the documentation of str2num states, it's a dangerous function to use (internally it uses eval so I could give you a string that would delete everything on your hard drive were you to pass it to str2num.)

Whenever possible prefer str2double which is guaranteed to not have any side effect.

Answer 1

[Matt J]

~any(isletter(yourMatrix(:)))

[Guillaume]

Performing the conversion and checking for NaNs would be more reliable. The above would be happy with '------' which is of course not a valid number.

[Leon]

Many thanks, Everyone, for your help!

Answer 2

[Matt J]

all(48<=yourMatrix(:) & yourMatrix(:)<=57)