Using subset() to select ranges of data - r

Question

I am new to R functions, always preferred to use packages and avoid loops. However, now I am trying to create a loop for a specific question that I have. I would like to subset a dataset based on ranges. I think the code below is self explanatory.
dt = as.data.frame(sample(1:100))
names(dt) = "num"
subs.it <- function(x) {
subs <- subset(dt, num >= (x - 5) & num <= (x + 5))
return(subs)
}
subs.it(c(15, 50))
wrong output:
num
44 55
47 20
65 19
77 17
83 12
91 16
92 51
100 54
correct:
num
4 15
18 11
47 20
50 13
54 10
65 19
66 14
77 17
82 18
83 12
91 16
17 48
19 53
29 45
33 52
39 46
44 55
45 50
49 49
89 47
92 51
100 54
I can't find what I am doing wrong.
Thanks

Answer 1

It seems like the function you are looking for is subset itself. Try:
subset(dt, num > 15 & num <50)
edit:
ah I see you want two different ranges. You can do this:
x = 15
y = 50
subset(dt, (num >= x-5 & num <= x+5) | (num >= y-5 & num <= y+5))
or a more compact version using absolute values:
subset(dt, (abs(num - x) <= 5 | abs(num - y) <= 5))

Answer 2

Here you go.
set.seed(12345)
library(dplyr)
subs.it <- function(x, y, z) {
subs <- x %>% filter(
(num >= (y-5) & num <= (y+5)) | (num >= (z-5) & num <= (z+5))
)
return(subs)
}
subs.it(dt, 15, 55)
num
1 16
2 14
3 15
4 55
5 52
6 17
7 56
8 13
9 57
10 54
11 18
12 53
13 11
14 58
15 19
16 10
17 51
18 60
19 20
20 50
21 12
22 59