I'm attempting to rename the level A of factor column1 in the dataframe df in R. My current approach is this:
levels(df[!is.na(df$column1) & df$column1 == 'A',]) <- 'B'
which doesn't throw any errors or warnings but is completely ineffective.
B is not an already existing level (which from trial and error I came to suspect was important), so the following, my first attempt, didn't work either
df[!is.na(df$column1) & df$column1 == 'A', 'column1'] <- 'B'
Could anyone guide me to the correct approach?
I was going to suggest
levels(df$column1)[levels(df$column1)=="A"] <- "B"
or use the utility function plyr::revalue:
library("plyr")
df <- transform(df,
column1=revalue(column1,c("A"="B")))
transform() is a little sugar that's not necessary; you could use df$column1 <- revalue(df$column1(...))
For completeness, car::recode also works, although I find it a little bit clunkier than plyr::revalue (because the recoding is specified as a quoted string).
car::recode(df$column1,"'A'='B'")
More recently forcats::fct_recode() can also be used for this.