Replace all occurrences of a string in a data frame

Question

I'm working on a data frame that has non-detects which are coded with '<'. Sometimes there is a space after the '<' and sometimes not e.g. '<2' or '< 2'. I'd like to remove every occurrence of the space.

Example:

data <- data.frame(name = rep(letters[1:3], each = 3), var1 = rep('< 2', 9), var2 = rep('<3', 9))    name var1 var2  1    a  < 2   <3 2    b  < 2   <3 3    c  < 2   <3 

This is where I've got to:

I can extract all the values and make the new strings but I can't put them back in the data frame.

index <- str_detect(unlist(data), '<') index <- matrix(index, nrow = 3)  data[index]  #[1] "< 2" "< 2" "< 2" "<3"  "<3"  "<3"   replacements <- str_replace_all(data[index], "<[ ]+","<")  replacements #[1] "<2" "<2" "<2" "<3" "<3" "<3"  data[index] <- replacements  #Error in `[<-.data.frame`(`*tmp*`, index, value = c("<2", "<2", "<2",  :  #  unsupported matrix index in replacement 

Answer 1

If you are only looking to replace all occurrences of "< " (with space) with "<" (no space), then you can do an lapply over the data frame, with a gsub for replacement:

> data <- data.frame(lapply(data, function(x) { +                  gsub("< ", "<", x) +              })) > data   name var1 var2 1    a   <2   <3 2    a   <2   <3 3    a   <2   <3 4    b   <2   <3 5    b   <2   <3 6    b   <2   <3 7    c   <2   <3 8    c   <2   <3 9    c   <2   <3