Create an array whose values depend on another array

If I have an array like

C = [1 2 3 4 5 2 4 5 6 7 6 2 5 7 8] 

I would like to obtain another array where the value of :

1,4,7 are substitued with 1.

2,5 with 2

3,6,8 with 3

to obtain:

F = [1 2 3 1 2 2 1 2 3 1 3 2 2 1 3] 

F should be a numeric vector and not a string or a character.

Which is the fastest and most efficient way?

Answer 1

[KALYAN ACHARJYA]

C=[1 2 3 4 5 2 4 5 6 7 6 2 5 7 8]
F=C;
idx=find(C==1 | C==4 | C==7);
F(idx)=1;
idx=find(C==2 | C==5);
F(idx)=2;
idx=find(C==3 | C==6 | C==8);
F(idx)=3;
F

Commad Window:

C =

     1     2     3     4     5     2     4     5     6     7     6     2     5     7     8


F =

     1     2     3     4     2     2     4     2     3     1     3     2     2     1     3

[madhan ravi]

You don’t need find() here, use logical indexing.

[KALYAN ACHARJYA]

yes @madhan ravi give me minutes please

This way

C=[1 2 3 4 5 2 4 5 6 7 6 2 5 7 8]
F=C;
F(C==1 | C==4 | C==7)=1
F(C==2 | C==5)=2
F(C==3 | C==6 | C==8)=3
F

right?

Thanks always!

[madhan ravi]

(C==1 | C==4 | C==7) * 1 + (C==2 | C==5) * 2 +...
    (C==3 | C==6 | C==8) * 3

[KALYAN ACHARJYA]

Great! @Madhan

[luca]

THANKS