Replacing numbers with letters in string

Question

I have an ID column with names like "155AB3EA157A3466887D8F4B99BABC35". I want to replace the numbers in these strings with letters. I've tried using gsub, but it produces an "invalid text argument" error. My code looks like this:

as.character(df$ID)
gsub("1", "A", df$ID)

I should add that I'm working with the ff package, because the data is very large.

Answer 1

IF we are replacing numbers 1-9 with LETTERS 'A' to 'I', then chartr is an option

chartr('123456789', 'ABCDEFGHI', v1)
#[1] "AEEABCEAAEGACDFFHHGDHFDBIIBABCCE"

Update

Just noticed that the OP was probably using an ffdf object

library(ff)
library(ffbase)

In that case, applying the functions in the regular manner results in error as the OP mentioned

gsub("1", "A", d$v1) 

Error in gsub("1", "A", d$v1) : invalid 'text' argument

So, we can use the specialized extraction functions like with.ffdf or within.ffdf from ffbase

with.ffdf(d, gsub("1", "A", v1))
#ff (open) integer length=1 (1) levels: A55AB3EAA57A3466887D8F4B99BABC35
#                         [1] 
#A55AB3EAA57A3466887D8F4B99BABC35 

For replacing the numbers 1-9, the chartr can be applied as

d$v1 <- with.ffdf(d, chartr('123456789', 'ABCDEFGHI', v1))
d
#ffdf (all open) dim=c(1,1), dimorder=c(1,2) row.names=NULL
#ffdf virtual mapping
#   PhysicalName VirtualVmode PhysicalVmode  AsIs #VirtualIsMatrix PhysicalIsMatrix PhysicalElementNo #PhysicalFirstCol PhysicalLastCol PhysicalIsOpen
#v1           v1      integer       integer FALSE           FALSE            FALSE                 1                1               #1           TRUE
#ffdf data
#                                v1
#1 AEEABCEAAEGACDFFHHGDHFDBIIBABCCE

data

v1 <- "155AB3EA157A3466887D8F4B99BABC35"
d <- as.ffdf(data.frame(v1))