Replacing rank value for each string in a character vector

Question

I have a character vector in R, and I want to assign a specific rank to each vector element and use this rank in my computations, how can I do this?

For example, the Degree vector is defined as follows:

Degree = c("low","med","high")

and I want to assign rank from 1 to 3 to each degree and replacing the degrees of defined vector with their ranks:

Blood_pressure = c("low","low","high","med","high")
Blood_pressure = c(1,1,3,2,3)

Answer 1

Simply use as.numeric and factor , like this:

Degree = c("low","med","high")
Blood_pressure = c("low","low","high","med","high")
as.numeric(factor(Blood_pressure, Degree))
# [1] 1 1 3 2 3

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Another option, which results in a named vector, is to create a named version of "Degree" and do basic matching. For example:

setNames(seq_along(Degree), Degree)[Blood_pressure]
#  low  low high  med high 
#    1    1    3    2    3