Warning: The assignment added rows to the table, but did not assign values to all of the table's existing variables. Those variables will extended with rows containing default values.

Why do I recieve this warning?

Answer 1

[dpb]

Apparently you had a table with N variables but only assigned values to a subset of those when adding rows.

Example:

>> x=rand(3,1);y=rand(3,1);  % some dummy data
>> t=table(x,y)              % turn into table
t =
  3×2 table
       x           y   
    ________    _______
    0.021833    0.20422
      0.3931    0.66228
     0.25254    0.91474
>> t.y(4)=0.5;              % add a y row, but forget about x
Warning: The assignment added rows to the table, but did not assign values to all of the
table's existing variables. Those variables have been extended with rows containing default
values. 
> In tabular/subsasgnDot (line 457)
  In tabular/subsasgn (line 67) 
>> t                        % so what did it do???
t =
  4×2 table
       x           y   
    ________    _______
    0.021833    0.20422
      0.3931    0.66228
     0.25254    0.91474
           0        0.5
>> 

As shown, it added the y value as asked, but filled in a zero (default value) for x.

Always add for every variable (even if want the default value) to avoid the warning. You could disable the warning if doing this deliberately, but I really wouldn't recommend that over explicit assignment.

[Sven Larsen]

your answer does not provide solution to problem at all. This error is received even, if we do:

t.x(4)=0.5;

t.y(4)=0.5;

Basic Matlab vagueness and annoyance...

[dpb]

Your code above still only added "x" the first time so the warning (and it is a warning, not a fatal error) is still correct; at that point there was still missing the corresponding "y"

As the Answer says, you must add all element of the table in the same operation to avoid the warning -- or, of course, you can always turn off the warning selectively if you're knowing you're going to be doing this in a section of code.

x=rand(3,1);y=rand(3,1);  % some dummy data
t=table(x,y);              % turn into table
xynew=[0.5 pi];
t=[t;array2table(xynew,'variablenames',t.Properties.VariableNames)]

t = 4×2 table
       x          y    
    _______    ________

    0.50943     0.47535
    0.50019     0.73985
    0.80566    0.044596
        0.5      3.1416

and, Voila! no warning.

I made an enhancement request/suggestion to create a new functionality for the table/timetable class of addrecord that would add the default record of proper type to the existing table either as empty, partially, or fully populated. Then, there would be specific syntax for the above.

t(end+1,:)=array2table(xynew,'variablenames',t.Properties.VariableNames)

t = 5×2 table
       x          y    
    _______    ________

    0.50943     0.47535
    0.50019     0.73985
    0.80566    0.044596
        0.5      3.1416
        0.5      3.1416

would be an alternative syntax to do the same thing.