Convert currency with commas into numeric

The reason why the gsub didn't work was there was , in the column, which is still non-numeric. So when convert to 'numeric' with as.numeric, all the non-numeric elements are converted to NA. So, we need to remove both , and $ to make it work.

df1$COL1 <- as.numeric(gsub('[$,]', '', df1$COL1))

We match the $ and , inside the square brackets ([$,]) so that it will be considered as that character ($ left alone has special meaning i.e. it signifies the end of the string.) and replace it with ''.

Or we can escape (\\) the character ($) to match it and replace by ''.

df1$COL1 <- as.numeric(gsub('\\$|,', '', df1$COL1))

We could use parse_number from readr package which removes any non-numeric characters.

#[1] 54345 65231 76234