How can I clear an entire table column without deleting the variable?

I have the following table and want to clear the variable P without deleting the variable. Is there a way how I can do that or should I just delete the variable by using removevars and add new data by 'new' variable P.

   P       Type        Date
0,43008   'Feeder'  '21.05.2018'
0,03786   'Feeder'  '21.05.2018'
0,37238   'Loader'  '21.05.2018'
...
(288x4 table)

Thanks in advance!

[Stephen23]

@s.h.m_89: what do "cleared" numeric values look like? What value/s would they have?

Answer 1

[Peter Perkins]

The short answer is to just overwrite the entire variable:

t.P = NaN(size(T.P))

You could also overwrite every element

t.P(:) = NaN

but there's not much advantage. In recent versions of MATLAB, you can assign missing:

t.P(:) = missing

but if you know the var is numeric, NaN is just as good. But missing works on other data types too, like categorical, datetime, ... . If you need to clear out variables of different types, using missing avoids a switch on the type.

By the way, you should consider making Type a categorical, and making Date a datetime. You may have already done that.

[s.h.m_89]

Many thanks Peter!

Answer 2

[sloppydisk]

You can simply overwrite the values by indexing with curly braces if that is what you want

t = table(rand(6, 1), rand(6, 1), rand(6, 1))
t{:, 1} = (1:6)';

[s.h.m_89]

Thanks, not exactly what I need. I need a solution where I can empty the whole column and after that refill it by indexing with other values. To see if there are missing values I can't just overwrite the values...

[Jeff Miller]

Do they really have to be missing? If not, maybe you could fill the column with NaN's and check for those instead of checking for missing. Or fill with a character and check for nonnumeric, etc.

[s.h.m_89]

Thanks everyone for your quick responses. @Jeff I did as you recommended. Many thanks!

[Walter Roberson]

NaN is the indicator of Missing for numeric entries for the purposes of tables. https://www.mathworks.com/help/matlab/ref/ismissing.html

You might also be interested in https://www.mathworks.com/help/matlab/ref/standardizemissing.html