recode letters to numbers

z = data.frame(matrix(sample(c(LETTERS[1:4],'NR',NA),100,replace=TRUE),20,5))
codes = c(A=100,B=27,C=50,D=25,NR=0)
newz = sapply(z,function(x)codes[x])

Hello,

I have a dataframe assigning various scores on around 20 variables to a list of
countries. The scores are rated on a scale of (D, C, B, A) and there are also
some not rated ones (NR) and others are left blank (NA). I now wanted to
transfer the scores into numeric values (such as NR=0, D=25, C=50, B=27, A=100),
while also leaving the NA in the dataframe. Can I transform the whole dataframe
at once or do I need to transform each column separately? How do I correctly
specify the levels and labels of the new dataframe?

Thank you so much,

Katharina



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