[R] If Then Trouble

[Sparks, John James]

Dear R Helpers,

I have another one of those problems involving a very simple step, but due
to my inexperience I can't find a way to solve it.  I had a look at a
number of on-line references, but they don't speak to this problem.

I have a variable with 20 values

> table (testY2$redgroups)

    1     2     3     4     5     6     7     8     9    10    11    12   
13    14    15    16    17    18    19    20
   69   734  6079 18578 13693  6412  3548  1646   659   323   129    88   
90    40    57    33    36    17     6    13

Values 18,19 and 20 have small counts.  So, I want to set the value of
redgroups for these rows to 17 in order to combine groups.  I would think
that it would be as easy as

if(testY2$redgroups>17) testY2$redgroups<-17

following the syntax that I have seen in the manuals.  However, I get the
error message

Warning message:
In if (testY2$redgroups > 17) testY2$redgroups <- 17 :
  the condition has length > 1 and only the first element will be used

Can someone please tell me the correct syntax for this?  I would really
appreciate it.

Appreciatively yours,
--John J. Sparks, Ph.D.