MATLAB: Matlab “missing” values not clear

MATLABstrings

Matlab holds some types of "<missing>" values in its string array. For instance
b =
3×3 string array
    "I"          <missing>    "MATLAB" 
    <missing>    "love"       "MATLAB" 
    "I"          "love"       <missing>
when I access each element of the array
b(1)
ans =
string
    "I"
b{1}
ans =
I
b(2)
ans =
string
    <missing>
b{2}
errormsg = Conversion of element 2 from missing to character vector is not supported.
what type of value is "missing", and why can't it simply be an empty character vector?

Best Answer

what type of value is "missing"
From the user point of view it's a flag for missing data. How it is implemented should not concern you and is not documented. (And I don't mean that in a negative way. We, as users, should not have to care, it should 'just work')
and why can't it simply be an empty character vector I don't know if it's a deliberate decision from mathworks or an oversight. However, there are plenty of cases where a missing string is not the same at all as an empty string.
Note that missing is brand new as of R2017a. As is documented the curly braces syntax is a compatibility layer for these codes that rely on cell array of char arrays and you should try to avoid it. It is indeed a bit unfortunate that that compatibility layer breaks in case of missing, so if you want that changed create a bug report with mathworks.
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