Separate several special rows based on row names by R - r

Question

I have a table that I want to separate some rows by row name.
phi psi
A-MET-0 NA 158.0945
A-VAL-1 -144.914 137.4733
A-LEU-2 -95.021 149.7834
A-SER-3 -82.6826 166.6769
B-GLU-4 -62.5314 -36.2634
H-GLY-5 -59.6463 -42.0355
A-GLU-6 -68.6914 -40.2354
AB-TRP-7 -63.5297 -36.769
A-GLN-8 -64.8056 -38.5128
I will separate a specific row according to the following command
tor$tbl["A-LEU-2",]
But when I try to separate a few rows, it gets an error.
I use the following command to separate several rows.
tor$tbl["A-LEU-2":"AB-TRP-7", ]
How can I separate several rows from the table based on the row name?
Thanks for guiding me.

Answer 1

Here's a function to do that -
subset_by_rowname_range <- function(data, start_name, end_name) {
rn <- rownames(data)
data[match(start_name, rn) : match(end_name, rn), ]
}
subset_by_rowname_range(df, "A-LEU-2", "AB-TRP-7")
# phi psi
#A-LEU-2 -95.0210 149.7834
#A-SER-3 -82.6826 166.6769
#B-GLU-4 -62.5314 -36.2634
#H-GLY-5 -59.6463 -42.0355
#A-GLU-6 -68.6914 -40.2354
#AB-TRP-7 -63.5297 -36.7690
subset_by_rowname_range(df, "H-GLY-5", "A-GLN-8")
# phi psi
#H-GLY-5 -59.6463 -42.0355
#A-GLU-6 -68.6914 -40.2354
#AB-TRP-7 -63.5297 -36.7690
#A-GLN-8 -64.8056 -38.5128
data
df <- structure(list(phi = c(NA, -144.914, -95.021, -82.6826, -62.5314,
-59.6463, -68.6914, -63.5297, -64.8056), psi = c(158.0945, 137.4733,
149.7834, 166.6769, -36.2634, -42.0355, -40.2354, -36.769, -38.5128
)), class = "data.frame", row.names = c("A-MET-0", "A-VAL-1",
"A-LEU-2", "A-SER-3", "B-GLU-4", "H-GLY-5", "A-GLU-6", "AB-TRP-7",
"A-GLN-8"))

Answer 2

A simple solution is by inserting row numbering, which can be used as indices for slice:
df %>%
mutate(row = row_number()) %>%
slice(1:8)
Alternatively, this would work too: here, which grabs the row.names' indices, by which slice can filter:
df %>%
slice(which(grepl("A-LEU-2", row.names(df))):which(grepl("AB-TRP-7", row.names(df))))