Convert a vector in Character array after a for loop

Hi, given the following code

n=length(x)
f = zeros(1,n)
for i = 1:n
if x(i) == 1 
f(1,i) = 22;
elseif x(i)==2
f(1,i) = 23;
elseif x(i)==3
f(1,i)= 21;
elseif x(i)==4
f(1,i) = 23;
elseif x(i)==5
f(1,i)= 24;
end
end

C= char (f)

I don't know why but the 'char' conversion doesn't work giving to me the following

so with nothing inside the vector, that I need later for a switch case.

Do you know how to fix the problem?

[madhan ravi]

madhan ravi:

I would probably use:

str = f + "" 

luca ruozi:

I need a character array and not a string, to run a switch cycle as I wrote above.

madhan ravi:

Could you illustrate how you want it to go?

luca ruozi:

n=length(x)
f = zeros(1,n)
for i = 1:n
if x(i) == 1 
f(1,i) = 22;
elseif x(i)==2
f(1,i) = 23;
elseif x(i)==3
f(1,i)= 21;
elseif x(i)==4
f(1,i) = 23;
elseif x(i)==5
f(1,i)= 24;
end
end
C=char(f)
T21=3
T22=2
T23=3
T24=2
for i = 1:n
    switch C
        case 21
            T21 = T21-1
        case 22
            T22 = T22-1
        case 23
            T23 = T23-1
        case 24
            T24 = T24-1
        otherwise
            disp ('dse')
            
    end
end

I want then to put C inside the switch cycle

[Stephen23]

"I don't know why but the 'char' conversion doesn't work "

Actually char works exactly as documented.

You provide the input values 22 to 24 to char, and those are the exact characters that char gives you. Here is a simple example:

>> x = randi(5,1,9)
x =
   5   1   3   2   2   3   4   2   3

then run your code to get exactly the non-printable characters that you requested:

>> f =
   24   22   21   23   23   21   23   23   21 
>> C = 

and checking that char did everything correctly:

>> double(C)
ans =
   24   22   21   23   23   21   23   23   21

The fact that you requested non-printable characters does not mean that char does not work, it just means that you need to learn about character encodings:

https://en.wikipedia.org/wiki/ASCII#Control_characters

[luca]

Thanks. But the mean problem is that I cannot use C inside the switch cycle. And I don't know why. May you help me?

[Stephen23]

"But the mean problem is that I cannot use C inside the switch cycle."

Actually you can: you just need to use exactly the same non-printable (and hence invisible) characters that you defined in C. Why you want complicate your life with non-printable characters is a mystery, but MATLAB is not stopping you from doing so.

"May you help me?"

I am not sure what you want: you told char to generate some non-printable characters, and so that is exactly what you got. What do you expect to happen? What are you actually trying to achieve?

http://xyproblem.info/

[Basil C.]

what exactly do the values

f(1,i) = 22;

f(1,i) = 23;

f(1,i) = 21;

Represent?

[luca]

What do you suggest to not complicate my life?

I don't know hot to do because I'm a really beginner. May you help me?

[luca]

Probably Char is not the right Command.

What I want to do is. Create a vector f through the for cycle and then use this vector as switch case. The SWITCH expression must be a scalar or a character vector, but in my case f is an array with numeric value. Do you know hot to do?

[Stephen23]

"I don't know hot to do because I'm a really beginner."

That is okay, we are here to help. But so far you have not actually described what you are trying to achieve: you have not explained how the result/output should be derived from the input, or provided example input and output arrays.

Without a specification we have to rely on guessing what you are trying to achieve.

Forget about code, what are you trying to do ?

Answer 1

[Stephen23]

Avoiding character manipulations using basic indexing:

>> x = [1,2,3,1];
>> V = 'A':'Z';
>> V(x)
ans = ABCA

[luca]

THANKS TO ALL

now the cose is working.

f= [1 2 3 4 1]

V = 'A':'Z';
V(f)

n=length(f)

for i=1:n
switch V(i)
    case 'A'
        disp ('aser')
    case 'B'
        disp ('sfe')
    case 'C'
        disp ('df4r')
    case 'D'
        disp ('at34tr')
    otherwise
        disp ('qwert')
end
end

Thanks to both of you

[luca]

Sorry may I ask you one more thing?

With basic indexing I have a problem. The fourth value is 1. 1 should be always the case A. But in this case is E. and the code display qwert.

Do you know how to fix in order to have Case A also for the fourth value.

THANKS

[Stephen23]

Instead of

switch V(i)

you need

switch V(f(i))

Otherwise you are just iterating over the elements of V, which is unlikely to be useful.

Answer 2

[Matt J]

Perhaps this is what you want?

>> f=[1,2,3,4], F=char(64+f)

f =

     1     2     3     4


F =

    'ABCD'

[luca]

What I want to do is Create a vector f through the for cycle and then use this vector as switch case. The SWITCH expression must be a scalar or a character vector, but in my case f is an array with numeric value. Do you know hot to do?

[Matt J]

You can loop over the elements of f,

n=length(x)
f = zeros(1,n)
for i = 1:n
 switch f(i)
     
     case 22
         
     case 23
         
     case 24
         
         ...
     
 end
end

but I have a nagging feeling that a switch-case is not the best way of doing whatever it is you're trying to do.