I am trying to define groupings from levels of factor variables and this the
warning message that R give
"& not meaningful for factors".
The nature of my task is this. I have a variable stage which has the levels
(1B, 2A, 2B) - these are the AJCC TNM stages of cancer, and another variable
diameter with factor levels ("=< 4", "4 - 6.5, > 6.5; limit values are
exclusive).
I am trying to define series of groupings based on these variables and others
like them.
My first attempts were;
1. node1 <- data.trt[data.trt$stage=="1B" & data.trt$diameter=="=< 4"]
2. data.trt$stage[data.trt$stage=="1B"]&
data.trt$diameter[data.trt$diameter=="=< 4"]
The second attempt was purely a fishing exercise.
R gave me the waring message:
Warning message:
In Ops.factor(data.trt$stage[data.trt$stage == "1B"],
data.trt$diameter[data.trt$diameter == :
& not meaningful for factors
My question is how do I get round this and by implication is there an
alternative way of defining a logical operation applicable to factors.
Thanks already for the help.
Philip
A Smile costs Nothing
But Rewards Everything
Happiness is not perfected until it is shared
-Jane Porter
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