[R] how to change automatically 0=no and 1=yes

[Muhammad Subianto]

Dear R-helpers,
I have dataset (data.frame) like below,
   x1  x2  x3   x4   x5  x6  x7  x8  x9 ... x1200
    0    0    0    1    1    0    0    1    1
    1    0    0    1    1    0    0    1    1
    0    1    0    1    1    0    0    1    1
    1    1    0    1    1    0    0    1    1
...
How can I change automatically 0=no and 1=yes.

Thank you very much in advance.
Kindly regards,
Muhammad Subianto