How to replace all elements in a Table?

For example, if I want to replace all -9999 with -999, I can do this in a matrix:

A(A==-9999) = -999;

My question is how to do this in a table that is generated by readtable?

A = readtable('test.xlsx');

When I tried, I got an error saying:

Operator '==' is not supported for operands of type 'table'.

Thank you.

[dpb]

Read the doc on accessing data in a table ...

Answer 1

[Ameer Hamza]

Accessing the elements of the table are different as compared to the matrix. One solution is to convert the table to an array and then do the replacement. In the end, convert the array back to MATLAB: https://www.mathworks.com/matlabcentral/answers/450426-replacing-elements-in-a-table. You can make replacement without doing the conversion to the matrix as follow.

num_vars = size(T, 2);
for i=1:num_vars
    T{:,i}(T{:,i}==-9999) = -999;
end

However, this will work as long as the class of every column in the table supports the comparison with double datatype using == operator.

[Leon]

Many thanks!

I do have unknow number of columns that can be text strings. Is there an easy way to implement it in that case?

[Ameer Hamza]

In that case, try this

for i=1:num_vars
    if isa(T{:,i}, 'double')
        T{:,i}(T{:,i}==1) = 100;
    end
end