I am trying to get rid of the first three characters of a string variable only for the first 18 observations (rows). How can I do this? I tried the code below but got an error: Error in parse(text = x) : :1:3: unexpected symbol
condition <- substring(Attend$"sample_label", 3)
filter_(Attend,condition) %>% slice(1:18)
please include more details. If I understand correctly, your dataframe is called Attend and the column of interest sample_label. If so, first of all, you do not need the quote marks (Attend$sample_label instead of Attend$"sample_label"). An easy way to do what you wish is the following:
library(dplyr)
Attend[1:18,]<-Attend[1:18,] %>%
mutate(sample_label=substring(sample_label, first=4))
We can use sub to remove first 3 characters for first 18 values in sample_label column.
Attend$sample_label[1:18] <- sub('.{3}', '', Attend$sample_label[1:18])
