Rename one level of a factor in R -

i'm attempting rename level a of factor column1 in dataframe df in r. current approach this:

levels(df[!is.na(df$column1) & df$column1 == 'a',]) <- 'b'

which doesn't throw errors or warnings ineffective.

b not existing level (which trial , error came suspect important), following, first attempt, didn't work either

df[!is.na(df$column1) & df$column1 == 'a', 'column1'] <- 'b'

could guide me correct approach?

i going suggest

levels(df$column1)[levels(df$column1)=="a"] <- "b"

or use utility function plyr::revalue:

library("plyr") df <- transform(df,           column1=revalue(column1,c("a"="b")))

transform() little sugar that's not necessary; use df$column1 <- revalue(df$column1(...))

for completeness, car::recode works, although find little bit clunkier plyr::revalue (because recoding specified quoted string).

car::recode(df$column1,"'a'='b'")

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