If Then Trouble
On 24.04.2011 22:10, Sparks, John James wrote:
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$redgroups<- 17 :
the condition has length> 1 and only the first element will be used
Can someone please tell me the correct syntax for this? I would really
appreciate it.
See help("if") and find if(foo) is only designed for scalar values of
foo. You actually want to use:
if(testY2$redgroups>17) testY2$redgroups<-17
testY2$redgroups[testY2$redgroups > 17] <- 17
or using some less efficient "if"-like statement:
testY2$redgroups <- ifelse(testY2$redgroups > 17, 17, testY2$redgroups)
Uwe Ligges
Appreciatively yours, --John J. Sparks, Ph.D.
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