Adding a Calculation as a field in an existing table.

Hello,

I have a 1x100 structure called 'a'. (See table). It is located in a .mat file. It has 100 rows, but the first 7 are visable in the screenshot.

In my script, I have an equation that calculates dynamic_k1 and dynamic_k2 by multiplying 12 to each of the 100 values of capacitance. I am able to print dynamic_k1 and dynamic_k2 and the math is correct, but I am wondering how I can add those 2 new calculations to the table as 2 new columns with 100 data points each.

Thank you.

Answer 1

[Walter Roberson]

Assuming that a is a struct array:

dynamic_k1 = 12 * vertcat(a.capacitance1);
dynamic_k2 = 12 * vertcat(a.capacitance2);

YourTable.dynamic_k1 = dynamic_k1;
YourTable.dynamic_k2 = dynamic_k2;

However, if a is your table then your syntax is wrong, and you should just do

a.dynanic_k1 = 12 * a.capacitance1;
a.dynanic_k2 = 12 * a.capacitance2;

[Sclay748]

It is a structure array, I will try it out and hope it works, thank you!

[Sclay748]

Hi Walter, sorry I was not able to try this until today. Power went out, (rolling california blackouts).

I tried this and got an error "scalar strucute required for this assignment. I tried both methods, but the table should be a structure, it says it at the top when I open it. 1x100struct. It is also named 'a'. This is what I did below.

dynamic_k1 = 12 * vertcat(a.capacitance1);

dynamic_k2 = 12 * vertcat(a.capacitance2);

a.dynamic_k1 = dynamic_k1;

a.dynamic_k2 = dynamic_k2;

[Walter Roberson]

If you are trying to assign a new field dynamic_k1 and dynamic_k2 into a structure array instead of into a table() object, then

dynamic_k1 = arrayfun(@(C.capacitance1) 12*C, a, 'uniform', 0);
dynamic_k2 = arrayfun(@(C.capacitance2) 12*C, a, 'uniform', 0);
[a.dynamic_k1] = dynamic_k1{:};
[a.dynamic_k2] = dynamic_k2{:};

Or let me see... maybe

a = arrayfun(@(S) setfield(S.dynamic_k1, 12*S.capacitance1), a);
a = arrayfun(@(S) setfield(S.dynamic_k2, 12*S.capacitance2), a);

But a loop might be more efficient:

for K = 1 : numel(a)
    a(K).dynamic_k1 = 12 * a(K).capacitance1;
    a(K).dynamic_k2 = 12 * a(K).capacitance2;
end