[R] Greater than less than in "ifelse"

[Richardson, Patrick]

I'm trying to categorize a continuous variable (yes, I know that's horrible, but I'm trying to reproduce some exercises from a textbook) and don't really know an efficient way to do this.

I have a data frame that looks like:

   surv_time relapse sex log_WBC rx
1         35       0   1    1.45  0
2         34       0   1    1.47  0
3         32       0   1    2.20  0
4         32       0   1    2.53  0

And I'm trying to categorize log_WBC into:

(0-2.30) = "low"
(2.31-3.00)= "medium"
(>3.00) = "high"

I've used an ifelse statement such as:

anderson$log_WBC <- ifelse(anderson$log_WBC<2.30,"low",anderson$log_WBC)

Is there a way to use "greater than" "less than" syntax within the context of an ifelse statement? Or can someone point me to a function that will do this easier.

Many Thanks,

Patrick

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