Assign a table coloumn a particular data type

For other reasons I cannot initialize my table as A=table but I must do A= zeros(height(B), 8) and then through array2table I convert my array into a table.

At this point how could I set A(:,2) and A(:,6) to datetime null values?

Answer 1

[Benjamin Kraus]

You cannot mix data types within a double matrix, but you can mix data types within a table.

So, you cannot convert two columns of A into datetime before creating the table.

I'm curious why you cannot create your table empty and then add colums as needed.

For example:

tbl = table;
B = zeros(10,1);
tbl.Var1 = B;
tbl.Var2 = NaT(size(B))

tbl = 10×2 table
    Var1    Var2
    ____    ____

     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 
     0      NaT 

However, if that doesn't work for some reason, maybe this is what you are looking for?

B = zeros(10,1);
A = zeros(height(B),8);
tbl = array2table(A);
tbl.A2 = NaT(height(A),1);
tbl.A6 = NaT(height(A),1)

tbl = 10×8 table
    A1    A2     A3    A4    A5    A6     A7    A8
    __    ___    __    __    __    ___    __    __

    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 

[Andrea Sbaragli]

Yes it works perfect thank you so much

[Steven Lord]

In recent releases:

types = repmat("double", 1, 8);
types([2 6]) = "datetime";
tbl = table('size', [10 8], 'VariableNames', "A"+(1:8), 'VariableTypes', types)

tbl = 10×8 table
    A1    A2     A3    A4    A5    A6     A7    A8
    __    ___    __    __    __    ___    __    __

    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0 
    0     NaT    0     0     0     NaT    0     0