Filter rows in a specific range values containing character and number in R

Question

I'm using RStudio to perform some analysis.

I have this data frame:

Residue	Energy	Model
R-A-40	-3.45	DELTA
R-A-350	-1.89	DELTA
R-B-468	-0.25	DELTA
R-C-490	-2.67	DELTA
R-A-610	-1.98	DELTA

I would like to filter the first column ("Residue") based on the numeric values (between 300 to 500) and create a new data frame. The new data frame would be like this:

Residue	Energy	Model
R-A-350	-1.89	DELTA
R-B-468	-0.25	DELTA
R-C-490	-2.67	DELTA

Note that it does not matter if starts with "R-A-", "R-B-" or "R-C-". However, I have different patterns (not only these three). I have to ignore the non-numeric characters or the first four characters from "Residue" column.

I did not find any similar question. I appreciate any help!

Thanks an advance

Answer 1

# convert character to integer
df$x <- as.integer(substr(df$Residue, 5, nchar(df$Residue)))

# subset
df[df$x %between% c(300,500), ]

Answer 2

Similar to one of the answers already given, but a little more readable:

library(tidyverse)

df <- tribble(~Residue, ~Energy,    ~Model,
              "R-A-40", -3.45,  "DELTA",
              "R-A-350",    -1.89, "DELTA",
              "R-B-468",    -0.25,  "DELTA")
df %>% 
  mutate(number = str_extract(Residue, "[:DIGIT:]+")) %>% 
  mutate(number = as.numeric(number)) %>% 
  filter(number >= 300 & number <= 500)