How to make multiple execution of a code by loop ?

Hello,

I have a code that uses one equation in order to take an output file. I use for my calculations randn so in each running of my code I have dofferent results. I would like to export for 100 executes of my code 100 outputs. I used this code

clc
clear

T=readtable('Outputresults.txt')

A=T(:,1)
B=T(:,2)
x=T(:,3)
x=table2array(x)
for i=1:100
y=randn +x

x=array2table(x)
y=array2table(y)

TABLE=[A B x y]
TABLE.Properties.VariableNames(1:6) = {'A','B','x','y'}
writetable(TABLE,['results' num2str(i) '.txt'],'Delimiter',' ')  

end

but command window shows me error after the first execution.

The error is:

Undefined operator '+' for input arguments of type 'table'.

Could you please help me?

Answer 1

[DGM]

Well, since I don't know what the error message was, then I'll just guess it was this.

T=readtable('Outputresults.txt')

A=T(:,1);
B=T(:,2);
xt=T(:,3);
x=table2array(xt); % you don't need to convert it back to a table a 100 times. 

for i=1:100
	y=randn+x;
	y=array2table(y);
	TABLE=[A B xt y]; % just use the table copy of x
	TABLE.Properties.VariableNames(1:4) = {'A','B','x','y'}; % you were assigning 4 things to 6 elements
	writetable(TABLE,['results' num2str(i) '.txt'],'Delimiter',' ');
end

[Ivan Mich]

The error is:

Undefined operator '+' for input arguments of type 'table'.

Could you please help me?

Answer 2

[Walter Roberson]

Replace

x=array2table(x)
y=array2table(y)
TABLE=[A B x y];
TABLE.Properties.VariableNames(1:4) = {'A','B','x','y'}; 

with

TABLE = table(A, B, x, y);

[Walter Roberson]

You were trying to do [A B x y] where x and y were already converted to table. But suppose your A or B is string() data type, then that would be a request to horzcat() string objects together with table objects. Concatenation with string objects is also the + operator, so that case of trying to concatenate string and table just might show up as an error about the + operator.

[Ivan Mich]

command window shows me:

Error using writetable (line 155)

Writing nested tables/timetables is not supported. Use SPLITVARS on the nested table

before writing.

Error in code (line 52)

writetable(TABLE,['results' num2str(i) '.txt'],'Delimiter',' ')

Could you help me?

[Walter Roberson]

T = readtable('Outputresults.txt');
T.Properties.VariableNames{1} = 'A';
T.Properties.VariableNames{2} = 'B';
T.Properties.VariableNames{3} = 'x';

xt = T{:,3};
for i = 1:10
    T.y = randn + xt;
    writetable(TABLE,['results' num2str(i) '.txt'],'Delimiter',' ');
end

Questions:

• are you sure you want to add a scalar random number each time, so you are adding the same number to each row of x? Or do you want to add a different random number to each row of x?
• when you add a random number, are you wanting to each time be using the data read in as the base? Or are you wanting to accumulate random numbers, so that the second output ?

%like the above, but the random numbers accumulate. And different one for
%each row
T = readtable('Outputresults.txt');
T.Properties.VariableNames{1} = 'A';
T.Properties.VariableNames{2} = 'B';
T.Properties.VariableNames{3} = 'x';

xt = T{:,3};
nxt = length(xt);
for i = 1:10
    xt = randn(nxt,1) + xt;
    T.y = xt;
    writetable(TABLE,['results' num2str(i) '.txt'],'Delimiter',' ');
end