CSV

library(readr)
df <- read_csv("thickness.csv")      # or another csv in your folder
glimpse(df)

Excel

library(readxl)
sheet_names("myfile.xlsx")
ex <- read_excel("myfile.xlsx", sheet = 1)
head(ex)

Clipboard (Windows)

clip_df <- read.table("clipboard", header = TRUE, sep = "\t")
head(clip_df)

Try it

• Import thickness.csv from /projects/datasets/ and compute mean and sd of the response.
• Save a subset with write_csv().