Regex colnames and grouping in R?

Question

I have this data frame:

id <- c(0,1,2,3,4)
groupA_sample1_values <- c(10,11,12,13,14)
groupA_sample2_values <- c(20,21,22,23,24)
groupA_sample3_values <- c(30,31,32,33,34)
groupB_sample1_values <- c(40,41,42,43,44)
groupB_sample2_values <- c(50,51,52,53,54)
groupB_sample3_values <- c(60,61,62,63,64)

df <- data.frame(id, 
                 groupA_sample1_values,
                 groupA_sample2_values,
                 groupA_sample3_values,
                 groupB_sample1_values,
                 groupB_sample2_values,
                 groupB_sample3_values)

df

and I am trying to obtain another table with these columns: id, group, sample, value. I belive I would have to extract the name groupA/groupB with regex, and the same for the sample number, and the melt it to a new data frame, but I'm not sure how to approach it. Any help?

Hi! it would very helpful if you provide an example of what you want to achieve, how the resulting data frame should look like — Marcelo Avila, Mar 22 '21 at 13:02
@MarceloAvila Thanks man, I'll take it into account the next time I ask. — CodingBiology, Mar 23 '21 at 16:08

score 1 · Accepted Answer · answered Mar 22 '21 at 11:43

try

library( tidyverse )
df %>%
  pivot_longer( -id,
                names_to = c("group", "sample" ),
                names_pattern = "group(.)_sample(.)_values",
                values_to = "value" )

# # A tibble: 30 x 4
#      id group sample value
#   <dbl> <chr> <chr>  <dbl>
# 1     0 A     1         10
# 2     0 A     2         20
# 3     0 A     3         30
# 4     0 B     1         40
# 5     0 B     2         50
# 6     0 B     3         60
# 7     1 A     1         11
# 8     1 A     2         21
# 9     1 A     3         31
#10     1 B     1         41

Regex colnames and grouping in R?

1 Answers1