Replacing elements in an array

Didn't find a relevant answer.

Suppose we have an array

R=[1 2 1 2 2 2]';
How to replace "2" with "4" ?
Thank you.

Answer 1

[michio]

R=[1 2 1 2 2 2]';
R(R==2) = 4;

See Logical Indexing – Multiple Conditions